||||||||||||||III USOO5155566A United States Patent (19) (1) Patent Number: 5,155,566 Nakayama et al. (45) Date of Patent: Oct. 13, 1992

(54) ORGANIC THIN FILM ELEMENT Harada et al; "Selective Observation of Outermost Sur (75) Inventors: Toshio Nakayama, Fujisawa; face Layer during ..."; pp. 2269-2272. Nobuhiro Gemma, Yokohama; Akira J. Chem. Soc. Faraday I, vol. 76; Jan. 1980; Peter Mee Miura, Toride; Katsuyuki Naito; han et al; "Neutron Diffraction from Benzene Adsorbed Syun Egusa, both of Yokohama, all on Graphite'; pp. 2011-2016. of Japan Primary Examiner-John D. Lee Assistant Examiner-Robert E. Wise 73) Assignee: Kabushiki Kaisha Toshiba, Kawasaki, Attorney, Agent, or Firm-Oblon, Spivak, McClelland, Japan Maier & Neustadt (21) Appl. No.: 675,964 (57 ABSTRACT (22 Filed: Mar. 27, 1991 An organic thin film element has a structure in which an organic thin film layer, an insulating layer, and a back (30) Foreign Application Priority Data electrode are sequentially formed on a substrate ob Mar. 27, 1990 (JP) Japan ...... 2-75413 tained by forming an electrode, an insulating layer and a layer consisting of polycyclic aromatic group mole 51) Int. Cl...... H01L 27/14: HOL 31 MOO cules or a derivative thereof or a carbon layer having a 52) U.S. Cl...... 357/30; 357/8 graphite structure on the surface of a substrate main 58) Field of Search ...... 357/30 R, 8 body. An effect of controlling the orientation of the (56) References Cited organic thin film layer can be enhanced by the surface layer of the substrate similar in chemical structure to U.S. PATENT DOCUMENTS molecules constituting the organic thin film layer. A 4,907,043 3/1990 Uekita et al...... 357/8 neutral-ionic transition of a complex can be effectively OTHER PUBLICATIONS caused by an electric field applied from the electrodes. Physical Review Letters, vol. 52; Jun. 18, 1984; Y. 14 Claims, 1 Drawing Sheet

2 U.S. Patent Oct. 13, 1992 5,155,566

F G.

YYYYYYYYYYYYYYYYYY 4. 2 YYYYYYYYYYYYYYYYYY g ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ2 5,155,566 1 2 effectively using the characteristics of organic mole ORGANICTHIN FILM ELEMENT cules as described above, control of a molecular struc ture on the order of a single molecule in a film, a mutual BACKGROUND OF THE INVENTION 1. Field of arrangement between neighboring molecules, and a the Invention 5 molecular orientation is very important as well as di The present invention relates to an organic thin film mensions such as a film thickness and structural unifor element. 2. Description of the Related Art mity. In recent years, attention has been increasingly paid Recently, as a method of manufacturing a very thin to molecular electronics using various physical proper film having controlled molecular orientation and struc ties of organic molecules to realize devices having novel O ture, a Langmuir-Blodgett (LB) method has become a functions not obtained by conventional semiconductor big concern. In this method, monomolecular films devices. For example, studies for applying organic mol formed on a water surface are accumulated on a sub ecules to a non-linear optical element, a switching ele strate one by one to form superlattice films of the same ment, and an electric-field light-emitting element have type or different types. Actually, however, a packing been actively made. From the viewpoint of the applica 15 state or uniformity of molecules in a film developed on tion of organic molecules to these elements, especially a the water surface is poor, and a monomolecular film charge-transfer phenomenon occurring between or structure is disturbed when it is accumulated on the ganic molecules has attracted attention. substrate. Therefore, this method has not yet reached Organic materials consist of donor molecules each the level capable of forming a superlattice thin film having a low ionization potential and a tendency to give 20 having a controlled molecular orientation in the entire an electron to another molecule to become a positive film or between the accumulated layers. To improve the ion and acceptor molecules each having a high electron film formation techniques according to the LB method, affinity and a tendency to receive an electron from it is necessary to design molecules suitable for the LB another molecule. It is well known that a compound method and to establish a synthesizing technique for called a charge-transfer complex is formed between 25 such molecules. these two types of molecules. For example, a compound On the other hand, as a technique requiring no spe of and tetracyanoquinodimethane (TCNQ) cific molecular design and capable of being easily ap consists of neutral molecules. On the other hand, a corn pound of tetramethylphenylenedianine (TMPD) and plied to most of organic molecules, a vacuum deposition TCNQ is an ionic compound in which molecules of the 30 method has been actively studied. In the vacuum depo respective substances become positive and negative sition method, however, a molecule evaporation source ions. It is also known that a neutral-ionic transition is temporarily gasified and aggregated again. Therefore, phenomenon according to a change in temperature or it is predicted that a film structure or a molecular orien pressure is observed in a compound of tetrathiafulva tation variously changes depending on a balance be lene (TTF) and chloranil (CA) (J. B. Torrance et al.: 35 tween the supply rate of gasified molecules, the rate of Phys. Rev. Lett., 46, 253 (1981). surface diffusion or crystallization of molecules depos To apply the charge-transfer phenomenon in organic ited on a substrate surface and an interaction between molecules as the operational principle of an electrical or adsorbed molecules and the substrate surface. optical element, it is important to cause charge-transfer In the conventional studies about an organic depos using an electric field or light with high efficiency and ited film, a thin film growth process and a molecular controllability. Data of interest, relating to electrical orientation of mainly long-chain hydrocarbon-based characteristics of the charge-transfer complex, has re linear molecules or tabular molecules such as phthalo cently been reported (Yoshiki Tokura et al.: Manu cyanine on various types of substrates have been exam scripts for Meeting of the Physical Society, 3a-S4-1, ined. A single-crystal alkali halide or a single-crystal 3a-S4-2, 3a-S4-3, etc. (Autumn 1988); Y. Tokura et al.: 45 metal, quartz, and an Sisingle crystal are mainly used as Physica 143B, 527 (1986)). Namely, it is reported that in substrates to execute evaluation using an electron mi a mixed stacked complex crystal in which donor mole croscope or electron-beam diffraction, optical evalua cules and acceptor molecules are stacked with their tion, and electrical evaluation, respectively. As the de molecular planes facing each other, the anisotropy of position conditions, influences of a substrate tempera relative dielectric constant is high, the relative dielec 50 ture and a deposition rate have been checked in many tric constant in the direction of stacking is very high, cases. Vincett et al. in U.S.A. has reported that a uni i.e., 100 to 1,000, and non-linear electric conductivity or form continuous film can be formed by setting a sub switching characteristics are observed under an electric strate temperature (on the absolute temperature scale) field on the order of 103 to 10 WAcm. The reason for to be the boiling point of a deposition material regard this is assumed that an ionic domain thermally or elec 55 less of the types of the deposition material and the sub trically formed in a neutral crystal or a neutral domain strate. However, it is very difficult to control the orien formed in an ionic crystal is dynamically moved by an tation of an organic thin film deposited on a given sub electric field. strate simply by setting proper deposition conditions. This phenomenon, though relating to neutral-ionic The following reports are known as researches on transition, occurs in a very local area, and no macro influences of a substrate on the molecular orientation of scopic change appears in the whole crystal. No macro an organic thin film formed thereon. (1) Karl et al. in scopic neutral-ionic transition caused by an electric West Germany have reported that in a perylenetet field or light has yet been realized. racarboxy dianhydride deposition film of several molec To cause a macroscopic neutral-ionic transition in a ular layers formed on a pure Sisingle-crystal surface, charge-transfer complex using an electric field, it is very 65 molecular planes are oriented parallel to the substrate important that the direction of the electric field in an surface. (2) Hara has reported, in the research on a element coincides with the direction of a stacking axis phthalocyanine deposited film using a molecular-beam of donor and acceptor molecules. To realize devices deposition method, that even under the conditions in 5,155,566 3. 4. that only a discontinuous film can be formed by normal According to the organic thin film element of the high-vacuum deposition, a uniform continuous film in present invention, since the surface of the substrate which molecular surfaces are oriented parallel to a sub consists of the polycyclic aromatic group molecules or strate surface can be formed at a very low deposition the derivative thereof or the carbon layer having a rate of about 0.1 nm/min under vary high vacuum. In 5 graphite structure any of which has a controlled orien this research, to avoid lattice mismatching between an tation, the orientation of the organic thin film layer inorganic substrate and deposited organic crystals, forthed on the substrate surface is improved. As a result, MoS2 which is a layered compound is used as a sub a neutral-ionic transition of a charge-transfer complex strate on the basis of the idea of Van der Waals epitaxy. in the organic thin film layer can be effectively con (3) Harada et al. have reported that molecular planes O trolled by an electric field. Such an effect of controlling are oriented parallel to a substrate surface in a penta the molecular orientation of an organic thin film layer cene deposited film of several molecular layers formed can be applied to any device using an organic thin film on a graphite substrate. such as a display element, a non-linear optical element, Although the various types of studies have been made a switching element, an electric field light-emitting on thin film formation according to the vacuum deposi 5 element, and an optical information recording medium. tion method as described above, control factors of the Additional objects and advantages of the invention film structure and the molecular orientation have not will be set forth in the description which follows, and in yet been totally understood. part will be obvious from the description, or may be The present inventors have made extensive studies learned by practice of the invention. The objects and with an emphasis on an interaction between a substrate 20 advantages of the invention may be realized and ob and deposited molecules. As a result, the present inven tained by means of the instrumentalities and combina tors have found that, when a film of aromatic group tions particularly pointed out in the appended claims. based molecules is to be deposited, a uniform continu ous film can be easily formed by using a highorientation BRIEF DESCRIPTION OF THE DRAWINGS graphite substrate having high similarity to a deposited 25 The accompanying drawings, which are incorpo film in terms of a chemical structure and an electronic rated in and constitute a part of the specification, illus structure and setting proper deposition conditions. In trate presently preferred embodiments of the invention, addition, it is assumed that a factor determining the and together with the general description given above orientation of an aromatic group-based molecules de and the detailed description of the preferred embodi posited on a high-orientation graphite substrate is a Van 30 ments given below, serve to explain the principles of the der Waals interaction occurring between m electrons on invention. the surface of the graphite substrate and those of the FIG. 1 is a sectional view showing an organic thin aromatic group-based molecules. That is, it is assumed film element according to the present invention; that the molecules are stabilized most in terms of energy FIG. 2 is a sectional view showing another organic by this interaction while their main molecular planes are 35 thin film element according to the present invention; oriented parallel to the substrate. However, it is difficult and to form an element as an electronic or optical device FIG. 3 is a sectional view showing an organic thin using a graphite substrate. film display element according to the present invention. As described above, to cause a neutral-ionic transi tion according to an electric field in a charge-transfer DETAILED DESCRIPTION OF THE complex of donor and acceptor molecules, the direction PREFERRED EMBODIMENTS of stacking axis of the complex must coincide with the The present invention will be described in more detail application direction of the electric field. However, it is below with reference to the accompanying drawings. very difficult to control the orientation of an organic An organic thin film element of the present invention thin film on a given substrate simply by setting proper 45. basically has a structure in which an organic thin film thin film formation conditions. If a graphite substrate is containing both donor and acceptor molecules is used and the formation conditions of an organic thin formed on a substrate (on the surface of which a layer film are properly set, the orientation of the organic thin consisting of polycyclic aromatic group molecules or a film can be easily controlled. However, it is difficult to derivative thereof or a carbon layer having a graphite form an element as an electronic or optical device using 50 structure is formed). Note that in a practical element, a a graphite substrate. substrate is used which an electrode, an insulating layer, and the layer consisting of polycyclic aromatic group SUMMARY OF THE INVENTION molecules or a derivative thereof or the carbon layer It is an object of the present invention to provide an having a graphite structure are formed on a substrate organic thin film element in which the structure and the 55 main body, and the organic thin film layer, an insulating orientation of an organic thin film can be controlled layer, and a back electrode are sequentially formed regardless of the material of a substrate and the type of thereon. The organic thin film layer may have a super stacking structure of layers and which can be put into lattice structure. practical use as a display element or the like. In the present invention, the material of the substrate According to the present invention, there is provided main body is not particularly limited but may be, e.g., a an organic thin film element comprising a substrate and metal, a semiconductor (including those having circuits an organic thin film layer formed on the substrate and or junctions), a dielectric, and quartz. Examples of the containing donor and acceptor molecules, wherein the electrode to be formed on the surface of substrate main substrate comprises a substrate main body and a layer body are a metal thin film and an ITO (indium tin ox consisting of polycyclic aromatic group molecules or a 65 ide). When an insulating layer is formed on the elec derivative thereof or a carbon layer having a graphite trode surface, this insulating layer functions to effec structure is formed on the surface of the substrate main tively apply an intense electric field on the organic thin body. film layer. That is, in general, as the intensity of an 5,155,566 5 6 electric field to be applied to an organic thin film layer are polyparaphenylenevinylene, polyimide, polyamide, is increased, an amount of a current flowing through the polyoxadiazole, and polybenzinidazole. organic thin film layer is largely increased. Therefore, Note that, when these polycyclic aromatic group the intensity of an electric field is limited to a certain molecules and their derivatives independently have level. On the other hand, when an insulating layer is donor or acceptor properties, the donor or acceptor formed between the electrode and the organic thin film properties are too weak to be put into practical use. layer, an amount of a current flowing through the or The substrate surface layer consisting of polycyclic ganic thin film layer is not increased even if an intense aromatic molecules or a derivative thereof can be electric field is applied. Therefore, an intense electric formed by a vacuum deposition method, an adsorption field can be effectively applied to the organic thin film O method, an LB method, a method of forming a film via layer to effectively cause charge transfer. Examples of a chemical bonding, or a heat polymerization method. the insulating layer are SiO2, SrTiO3, and an organic Charged particles may be radiated on a film formed by polymer. To apply a higher electric field to the organic these methods. thin film layer, it is preferred to use an insulating mate More specifically, the adsorption method includes, rial having a relative dielectric constant of 10 or more, 15 e.g., a method in which a substrate main body is dipped e.g., a ferroelectric such as SrTiO3. in a solution of polycyclic aromatic group molecules or In addition, to form a carbon layer having a graphite a derivative thereof and a solvent is evaporated; and a structure on the surface of the substrate main body, it is method in which a substrate main body is left to stand in preferred to form a thin film underlayer consisting of a a vapor of polycyclic aromatic group molecules or a transition metal having d or f electrons such as Pt, Pd, 20 derivative thereof. Ni, Ir, Rh, Co, Os, Ru, Fe, Re, Pr, Nd, Sm, Eu, Gd, Tb, When the LB method is to be used, a derivative is Dy, Ho, or Yb or a transition metal carbide such as WC, synthesized by introducing at least one hydrophobic TiC, TaC, or HfC. group to polycyclic aromatic group molecules, and a In the present invention, examples of the polycyclic substrate main body is subjected to a hydrophobic treat aromatic group molecules and the derivative thereof 25 ment beforehand. A solution of the polycyclic aromatic constituting the surface layer of the substrate are a ben group molecular derivative is dropped on a water sur zenoid-based condensed aromatic group, a bicyclic or face to develop a monomolecular film, and the devel polycyclic ring group, a non-benzenoid-based aromatic oped monomolecular film is compressed and accumu group, a heterocyclic aromatic group, a condensed lated on the substrate main body by either a horizontal 30 adhesion method or a vertical dipping method. In this aromatic group derivative, a macrocyclic aromatic method, by setting the number of hydrophobic groups group, and an aromatic group-based polymer. and the surface pressure of the monomolecular film to Examples of the benzenoid-based condensed aro be proper values, a layer in which main molecular matic group are , , , planes of the polycyclic aromatic molecules are ori , heptaphene, , benza)anthracene, 35 ented parallel to the surface of the substrate main body , benzocphenanthrene, , dibenza,jan can be formed. thracene, dibenza,c)anthracene, dibenza,hlanthracene, An example of the method of forming a film via a naphth2,3-alanthracene, naphth2, 1-alanthracene, ben chemical bonding is a method in that a silane derivative zoanaphthacene, naphtho2,3-anaphthacene, diben of polycyclic aromatic group molecules is used to cause zoa,lnaphthacene, dibenzoa.jnaphthacene, diben a condensation reaction with hydroxyl groups on the zoc,gphenanthrene, , perylene, 1,12-benzopy surface of an insulating layer (e.g., SiO2) on the sub rene, naphtho2, 1-alpyrene, dinaphthoanthracene, tery strate main body, thereby forming a film consisting of lene, quarterylene, benzo(a)pyrene, benze)pyrene, the polycyclic aromatic group molecular derivative. (18)annulene, 2,3;8,9-dibenzoperylene, anthracen2, 1 Especially when a plurality of functional groups for aanthracene, phenanthren (2,3-alanthracene, tribenz 45 causing the condensation reaction are introduced to the (a,c,h)anthracene, naphtho(2,3-alpyrene, dibenzoa,i- polycyclic aromatic group molecules, the molecular pyrene, dibenzoa,l)pyrene, cedrene, anthantholene, planes of the polycyclic aromatic group molecules can tetrabenzonaphthalene, , tetrabenza,c,hjan be easily oriented parallel to the substrate main body. thracene, pyranthrene, bisanthrene, benzobisanthrene, Examples of the polycyclic aromatic group molecular 1,2,7,8-dibenzocoronene, 2,3;8,9-dibenzocoronene, ova 50 derivative usable in the present invention are a chlorosi lene, hexabenzocoronene, tribenzoa,i,lpyrene, vi lane derivative such as a dichlorodimethylsilyl deriva olanthrene, tetrabenzoa,cd,j,lmperylene, diphenan tive, a dichlorodiphenylsilyl derivative, a trichlorosilyl throperylene, anthrabenzonaphthopentacene, 1,9,5,10 derivative, a bis(trichlorosilyl) derivative, a tris(tri diperynaphthyleneanthracene, dinaph chlorosilyl) derivative, and a tetrakis(trichlorosilyl) tho7", 1";1,13;1",7";6,8peropyrene, decabenzanthra derivative. In addition, a derivative obtained by intro cene, and diphenylenenaphthacene. Examples of the ducing a titanate coupling agent or a metal complex ring group are biphenyl, terphenyl, and quarterphenyl. surface modifier used in a metal surface treatment to Examples of the non-benzenoid-based aromatic group polycyclic aromatic group molecules can be used. To are , , decacyclene, diindeno1,2,3- the contrary, the surface of a substrate main body may cd; 1,2',3'-lm)perylene, and . Examples of the be modified by a YRSiX3-type silane coupling agent heterocyclic aromatic group are carbazole, acridine, containing an epoxy group or an amino group to cause phenazine, and thianthrene. Examples of the condensed the condensation reaction with polycyclic aromatic aromatic group derivative are perylenequinone, violan group molecules or a derivative thereof. throne, isoviolanthrone, naphthalic anhydride, naph In the heat polymerization method, after a film con thalenetetracarboxylic dianhydride, and perylenetet 65 sisting of a crosslinking polycyclic aromatic group mo racarboxylic dianhydride. Examples of the macrocyclic lecular derivative, a film mixture of polycyclic aromatic aromatic group are keclene, phthalocyanine, and por group molecules or a derivative thereof with a cross phyrin. Examples of the aromatic group-based polymer linking agent, or a film of an aromatic group polymer is 5,155,566 7 8 formed on a substrate main body, a heat treatment is crease of the electric field formed by the carriers can be performed to polymerize or condense the molecules in prevented. In addition, if the complex is ionic, by reduc the film, thereby forming a larger polycyclic aromatic ing contribution of a Madelung energy term of complex group molecular skeleton. stabilizing energy by decreasing the film thickness, the When charged particles are radiated on a film formed complex transits to be neutral. Therefore, the charge by a method except for the heat polymerization method, transfer state of the complex can be set close to bound polycondensation between the molecules is accelerated ary conditions of transition. to form a larger polycyclic aromatic group molecular The organic thin film layer may have a superlattice skeleton. Examples of the charged particles are an elec structure in which a plurality of complex layers and tron beam, an ion beam, and plasma. When charged O layers consisting of polycyclic aromatic are stacked. particles are used, molecules can efficiently undergo With this structure, changes in neutral-ionic states of polycondensation without requiring a high temperature the plurality of complexes can be controlled by a volt unlike in the heat polymerization. In addition, by radiat age change. ing a patterned beam of charged particles, a predeter In the present invention, when an insulating layer is mined pattern of a film having a larger polycyclic aro 15 to be formed on the organic thin film layer, an organic matic group molecular skeleton can be formed, and a polymer film is preferably formed by the vacuum depo pattern of an organic thin film layer can be formed sition method to prevent the organic thin film from thereon so as to be self-aligned therewith. being adversely affected. A metal thin film or the like The carbon layer having a graphite structure is can be used as the back electrode. formed by adsorbing hydrocarbon on the surface of the 20 In the organic thin film element of the present inven substrate main body and thermally decomposing the tion, a layer in that main molecular planes of polycyclic adsorbed hydrocarbon. Such a thermal structural aromatic group molecules, on the molecular planes of change in the surface-adsorbed species is reported by which n electrons spread, are oriented parallel to the Lang et al. ("Surface Science", 53, (1975) 317). In this substrate main body, or a carbon layer having a graphite case, if a thin film of a transition metal or a transition 25 structure is formed. Therefore, a surface electron struc metal carbide is formed on the surface of the substrate ture similar to the cleavage plane of a graphite single main body as described above, the thermal structural crystal can be obtained on a given substrate main body. change in adsorbed hydrocarbon can be accelerated. In addition, since the chemical structure of the substrate More specifically, when several tens to several hun surface is similar to that of the molecules constituting dreds Langmuir of hydrocarbon gas such as ethylene or 30 the organic thin film layer formed on the substrate, an acethylene are adsorbed at a substrate temperature of effect of controlling the orientation of the organic thin 500 to 1,500 K, a dehydrogenation reaction progresses film layer is enhanced. Therefore, since the neutral to form a carbon layer having a graphite structure. ionic transition in a complex can be effectively caused By these methods, polycyclic aromatic group mole by an electric field, an organic thin film element which cules or carbon layer having a graphite structure can be 35 can be put into practical use as, e.g., a display element formed on the surface of the substrate main body with can be provided. Similarly, by arbitrarily setting the their molecular planes oriented parallel to the surface of electrical characteristics or the optical characteristics of the substrate main body. As a result, a surface structure the substrate main body, an organic thin film element similar to the cleavage plane of a graphite single crystal having desired functions can be manufactured. can be obtained, The structures and the operational principles of the In the present invention, as the organic thin film con organic thin film elements according to the present taining both the donor and acceptor molecules, a mixed invention will be briefly described below. stacked charge-transfer complex crystal in which the (a) Display Element molecules are stacked with their molecula planes facing A display element according to the present invention each other is preferably used. When the mixed stacked 45 has a structure in that an organic thin film layer, an charge-transfer complex is used, a structure in which insulating layer, and a back electrode are sequentially the donor and acceptor molecules are alternately formed on a substrate constituted by a transparent sub stacked is automatically constructed during a film strate main body, a transparent electrode, an insulating growth step, thereby increasing the efficiency of charge layer, and a layer consisting of polycyclic aromatic transfer. 50 group molecules or a derivative thereof or a carbon Examples of the mixed stacked charge-transfer com layer having a graphite structure. In this display ele plex are phenothiazine-TCNQ, tetradiaminopyrene ment, an electric field is applied from the electrodes to TCNQ, TTF-chloranil, TTF-fluoranil, dibenzoTTF the organic thin film layer. As a result, since a mixed TCNQ, diethyldimethyltetraselenafulvalene-die stacked charge-transfer complex constituting the or thylTCNQ, tetradiaminopyrene-fluoranil, TTF. 55 ganic thin film layer is caused to transit from a neutral dichlorodicyanobenzoquinone, perylenetetracyano to ionic state to change its light absorption wavelength, ethylene, perylene-TCNQ, TTF-dinitrobenzene, pery a display function can be obtained. lene-chloranil, pyrene-tetracyanoethylene, pyrene (b) Field-Effect (FET) chloranil, anthracene-chloranil, hexanethylbenzene An FET according to the present invention has a chloranil, naphthalene-tetracyanoethylene, anthracene basic structure in that a gate insulating film, a layer pyromellitic dianhydride, anthracenetetracyanoben consisting of polycyclic aromatic group molecules or a zene, and -pyromellitic dianhydride. derivative thereof or a carbon layer having a graphite If the thickness of the organic thin film layer contain structure, an organic thin film layer, and a gate elec ing both the donor and acceptor molecules is large, the trode are sequentially formed on a channel region de level of an effective electric field to be applied to the 65 fined between source and drain regions formed on the film is decreased by an electric field formed by carriers surface of a semiconductor substrate. generated in the film. However, if the thickness of the In this FET, when a gate voltage is gradually in film is its Debye length (abou 30 nm) or less, the de creased, a mixed stacked charge-transfer complex con 5,155,566 10 stituting the organic thin film layer transits from a neu tral to ionic state at a certain voltage level to abruptly EXAMPLE 3 increase a drain current. As a result, a switching func A violanthrene film having a film thickness of about tion is obtained. 5 nm was formed on an Si substrate main body at a Note that in either of the above two devices, a multi 5 substrate temperature of 55 C. by the vacuum deposi value display or switching function can be obtained by tion method. A phenothiazine-TCNQ film having a film adopting a superlattice structure in the organic thin film thickness of about 10 nm was formed on the resultant layer. substrate by the vacuum deposition method. The present invention will be described in more detail When the film was observed by the SEM, it was below by way of its examples. In the following exam 10 confirmed that a uniform continuous film in which the ples, organic thin film layers having structures shown in size of one domain reached 10 um was formed. In addi FGS. 1 to 3 are formed. tion, the orientation of the film was checked by the In the organic thin film element shown in FIG. 1, a X-ray diffraction method. As a result, it was confirmed layer 5 which is either a layer consisting of polycyclic that molecular planes of complex crystal unit cells were aromatic group molecules or a derivative thereof or a 15 oriented substantially parallel to the substrate surface. carbon layer having a graphite structure is formed on the surface of a substrate main body 11, and an organic EXAMPLE 4 thin film layer 12 is formed thereon. A violanthrene film having a film thickness of about The organic thin film element shown in FIG. 2 has a 20 5 nm was formed on an Si substrate main body at a superlattice structure in that a layer 5 consisting of substrate temperature of 55 C. by the vacuum deposi polycyclic aromatic group molecules or a derivative tion method. A TCNQ film having a film thickness of thereof is formed on the surface of a substrate main about 100 nm, a violanthrene film having a film thick body 11, and a first organic thin film layer 12, a layer 5 ness of about 5 nm, and a phenothiazine-TCNQ film consisting of a polycyclic aromatic group molecules or 25 having a film thickness of about 10 nm were formed on a derivative thereof, and a second organic thin film the resultant substrate by the vacuum deposition layer 13 are sequentially formed thereon. method. In the organic thin film element shown in FIG. 3, an When the film was observed by the SEM, it was electrode 2, an insulating layer 3, and a layer which is confirmed that a uniform continuous film was formed either a layer consisting of polycyclic aromatic group 30 throughout several m. In addition, the orientation of molecules or a derivative thereof or a carbon layer 5 the film was checked by the X-ray diffraction method. having a graphite structure are formed on the surface of As a result, it was confirmed that molecular planes of a substrate main body 11, and an organic thin film layer complex crystal unit cells were oriented substantially 12, an insulating layer 14, and a back electrode 15 are parallel to the substrate surface. sequentially formed. 35 EXAMPLE 5 EXAMPLE An Si substrate main body was dipped in a toluene A decacyclene film having a film thickness of about solution of coronene and heated at 80 C. to evaporate 10 nm was formed on an Si substrate main body at a the solvent, thereby forming a coronene film. A pheno substrate temperature of 50° C. by a vacuum deposition thiazine-TCNQ film having a film thickness of about 30 method. A TCNQ film having a film thickness of about nm was formed on the resultant substrate at a substrate 100 nm was formed on the resultant substrate by the temperature of 50° C. by the vacuum deposition vacuum deposition method. method. When the film was observed by a scanning electron When the film was observed by the SEM, it was microscope (SEM), it was confirmed that a uniform 45 confirmed that a uniform continuous film in which the continuous film in which the size of one domain reached size of one domain reached 10 m was formed. In addi 10 um was formed. In addition, the orientation of the tion, the orientation of the film was checked by the film was checked by an X-ray diffraction method. As a X-ray diffraction method. As a result, all molecular result, it was confirmed that molecular planes on one planes of a phenothiazine-TCNQ complex were ori side of TCNQ crystal unit cells having a herring bone 50 ented substantially parallel to the substrate surface. structure were oriented parallel to the substrate surface. EXAMPLE 6 EXAMPLE 2 An Si substrate main body was dipped in a toluene A violanthrene film having a film thickness of about solution of coronene and heated at 80' C. to evaporate 5 nn was formed on an Si substrate main body at a 55 the solvent, thereby forming a coronene film. A vi substrate temperature of 55 C. by the vacuum deposi olanthrene film having a film thickness of 2 nm and a tion method. A phthalocyanine film having a film thick phenothiazine-TCNQ film having a film thickness of ness of about 500 nm was formed on the resultant sub about 30 nm were formed on the resultant substrate at a strate by the vacuum deposition method. substrate temperature of 50 C. by the vacuum deposi When the film was observed by the SEM, it was tion method. confirmed that a uniform continuous film in which the When the film was observed by the SEM, it was size of one domain reached 10 um was formed. In addi confirmed that a uniform continuous film in which the tion, the orientation of the film was checked by the size of one domain reached 10 um was formed. In addi X-ray diffraction method. As a result, it was confirmed 65 tion, the orientation of the film was checked by the that molecular planes on one side of phthalocyanine X-ray diffraction method. As a result, all molecular crystal unit cells having a herringbone structure were planes of a phenothiazine-TCNQ complex were ori oriented parallel to the substrate surface. ented substantially parallel to the substrate surface. 5,155,566 11 12 200 nm as an insulating layer were formed on a quartz EXAMPLE 7 substrate main body. A monomolecular film containing An ITO transparent electrode having a film thickness tetra t-butylphthalocyanine and octadecane at a mixing of 400 nm and an SiO2 film having a film thickness of ratio of 1 : 4 was developed on a water surface, and 200 nm as an insulating layer were formed on a quartz 5 three layers of this monomolecular film were accumu substrate main body. The resultant substrate was dipped lated on the resultant substrate. A violanthrene film in a toluene solution of coronene and heated at 80 C. to having a film thickness of 3 nm and a phenothiazine evaporate the solvent, thereby forming a coronene film. TCNQ film having a film thickness of about 30 nm were A violanthrene film having a film thickness of 2 nm and formed on the substrate at a substrate temperature of 55 a phenothiazine-TCNQ film having a film thickness of O C. by the vacuum deposition method. In addition, a about 30 nm were formed on the substrate at a substrate polyisobutylmethacrylate film having a film thickness temperature of 50 C. by the vacuum deposition of 20 nm as an insulating layer and an Au semitranspar method. In addition, a polyisobutylmethacrylate film ent electrode. having a film thickness of 25 nm were having a film thickness of 20 nm as an insulating layer formed on the phenothiazine-TCNQ film to manufac and an Au semitransparent electrode having a film 15 ture an organic thin film element. thickness of 25 nm were formed on the phenothiazine When no voltage was applied, the organic thin film TCNQ film to manufacture an organic thin film ele layer of this element exhibited an orange color. When a ment. voltage was applied to the organic thin film layer, the When no voltage was applied, the organic thin film color of the layer changed to dark red at a voltage of layer of this element exhibited an orange color. When a 20 about 30 V. voltage was applied to the organic thin film layer, the color of the layer changed to dark red at a voltage of EXAMPLE ll about 30 V. An Si substrate main body was left to stand in a bistri chlorosilylpyrene vapor phase for a surface treatment. EXAMPLE 8 25 A TTF-chloranil film having a film thickness of about An Si substrate main body was left to stand in a hexa 30 nm was formed on the resultant substrate by the methyldisilazane vapor phase for a hydrophobic treat vacuum deposition method. ment. A monomolecular film containing tetra t-butylph When the film was observed by the SEM, it was thalocyanine and octadecane at a mixing ratio of 1 : 4 confirmed that a uniform continuous film in which the was developed on a water surface, and three layers of 30 size of one domain reached 10 um was formed. In addi this monomolecular film were accumulated on the sub tion, the orientation of the film was checked by the strate main body. A phenothiazine-TCNQ film having a X-ray diffraction method. As a result, it was confirmed film thickness of about 30 nm was formed on the resul that molecular planes of both the TTF and chloranil tant substrate at a substrate temperature of 50° C. by the molecules were oriented substantially parallel to the vacuun deposition method. 35 substrate surface. When the film was observed by the SEM, it was confirmed that a uniform continuous film in which the EXAMPLE 2 size of one domain reached 10 um was formed. In addi An ITO transparent electrode having a film thickness tion, the orientation of the film was checked by the of 400 nm and an SiO2 film having a film thickness of X-ray diffraction method. As a result, it was confirmed 40 150 nm as an insulating layer were formed on a quartz that all molecular planes of a phenothiazine-TCNQ substrate main body. The resultant substrate was sub complex were oriented substantially parallel to the sub jected to a surface treatment in a bistrichlorosilylpyrene strate surface. vapor phase. A TTF-chloranil film having a film thick ness of about 30 nm was formed on the substrate by the EXAMPLE 9 45 vacuum deposition method. In addition, a polyisobutyl An Si substrate main body was left to stand in a hexa methacrylate film having a film thickness of 20 nm as an methyldisilazane vapor phase for a hydrophobic treat insulating layer and an Au Semitransparent electrode ment. A monomolecular film containing tetra t-butylph having a film thickness of 20 nm were formed on the thalocyanine and octadecane at a mixing ratio of 1 : 4 TTF-chloranil film to manufacture an organic thin film was developed on a water surface, and three layers of 50 element. this nonomolecular film were accumulated on the sub When no voltage was applied, the organic thin film strate main body. A violanthrene film having a film layer of this element exhibited a yellow color. When a thickness of 3 nm and a phenothiazine-TCNQ film hav voltage was applied to the organic thin film layer, the ing a film thickness of about 30 nm were formed on the color of the layer changed to red at a voltage of about resultant substrate at a substrate temperature of 55' C. 55 50 V. by the vacuum deposition method. When the film was observed by the SEM, it was EXAMPLE 13 confirmed that a uniform continuous film in which the An ITO transparent electrode having a film thickness size of one domain reached 10 um was formed. In addi of 400 nm and an SrTiO3 film having a film thickness of tion, the orientation of the film was checked by the 60 200 nm as an insulating layer were formed on a quartz X-ray diffraction method. As a result, it was confirmed substrate main body. The resultant substrate was sub that all molecular planes of a phenothiazine-TCNQ jected to a surface treatment in a bistrichlorosilylpyrene complex were oriented substantially parallel to the sub vapor phase. A TTF-chloranil film having a film thick strate surface. ness of about 30 nm was formed on the substrate by the vacuum deposition method. In addition, a polyisobutyl EXAMPLE 10 methacrylate film having a film thickness of 20 nm as an An ITO transparent electrode having a film thickness insulating layer and an Au semitransparent electrode of 400 nm and an SiO2 film having a film thickness of having a film thickness of 20 nm were formed on the 5,155,566 13 14 TTF-chloranil film to manufacture an organic thin film When no voltage was applied, the organic thin film element. layer of this element exhibited a yellow color. When a When no voltage was applied, the organic thin film voltage was applied to the organic thin film layer, the layer of this element exhibited a yellow color. When a color of the layer changed to red at a voltage of about voltage was applied to the organic thin film layer, the 5 25 V. color of the layer changed to red at a voltage of about 25 V. EXAMPLE 17 EXAMPLE 14 A perylenetetracarboxylic dianhydride film having a film thickness of 20 nm was formed on an Si substrate An Si substrate main body was subjected to a surface 10 main body, and the resultant substrate was heated up to treatment in a y-aminopropyltriethoxysilane vapor 550 C. in an argon atmosphere. As a result, most of the phase. Perylenetetracarboxylic dianhydride was depos film changed to polyperynaphthalene. A pheno ited on the resultant substrate by the vacuum deposition thiazineTCNQ film having a film thickness of about 30 method, and the substrate was heated up to about 70' C. nn was formed on the resultant substrate at a substrate to cause a condensation reaction and redissociation of 15 temperature of 50 C. by the vacuum deposition non-condensed molecules. Thereafter, a TTF-chloranil method. film having a film thickness of about 30 nm was formed. When the film was observed by the SEM, it was When the film was observed by the SEM, it was confirmed that a uniform continuous film in which the confirmed that a uniform continuous film in which the size of one domain reached 10 m was formed. In addi size of one domain reached 10 um was formed. In addi tion, the orientation of the film was checked by the tion, the orientation of the film was checked by the X-ray diffraction method. As a result, it was confirmed X-ray diffraction method. As a result, it was confirmed that all molecular planes of a phenothiazine-TCNQ that molecular planes of both the TTF and chloranil complex were oriented substantially parallel to the sub molecules were oriented parallel to the substrate sur strate surface, face. 25 EXAMPLE 1.5 EXAMPLE 1.8 An ITO transparent electrode having a film thickness A perylenetetracarboxylic dianhydride film having a of 400 nm and an SiO2 film having a film thickness of film thickness of 20 nm was formed on an Si substrate 150 nm as an insulating layer were formed on a quartz 30 main body, and the resultant substrate was heated up to substrate main body. The resultant substrate was sub 550 C, in an argon atmosphere. As a result, most of the jected to a surface treatment in a y-aminopropyltrie film changed to polyperynaphthalene. A violanthrene thoxysilane vapor phase. Perylenetetracarboxylic dian film having a film thickness of about 2 nm and a pheno hydride was deposited on the resultant substrate by the thiazine-TCNQ film having a film thickness of about 30 vacuum deposition method, and the substrate was nm were formed on the resultant substrate at a substrate heated up to about 70° C. to cause a condensation reac temperature of 50° C. by the vacuum deposition tion and re-dissociation of non-condensed molecules. method. Thereafter, a TTF-chloranil film having a film thick When the film was observed by the SEM, it was ness of about 30 nm was formed. In addition, a confirmed that a uniform continuous film in which the polyisobutylmethacrylate film having a film thickness 40 size of one domain reached 10 m was formed. In addi of 20 nm as an insulating layer and an Au semitranspar tion, the orientation of the film was checked by the ent electrode having a film thickness of 20 nm were X-ray diffraction method. As a result, it was confirmed formed on the TTF-chloranil film to manufacture an that all molecular planes of a phenothiazine-TCNQ organic thin film element. complex were oriented substantially parallel to the sub When no voltage was applied, the organic thin film 45 strate surface. layer of this organic thin film element exhibited a yel low color. When a voltage was applied to the organic EXAMPLE 9 thin film layer, the color of the layer changed to red at An ITO transparent electrode having a film thickness a voltage of about 50 V. of 400 nm and an SiO2 film having a film thickness of SO 200 nm as an insulating layer were formed on a quartz EXAMPLE 6 substrate main body. A perylenetetracarboxylic dianhy An ITO transparent electrode having a film thickness dride film having a film thickness of 20 nm was formed of 400 nm and an SrTiO3 film having a film thickness of on the resultant substrate, and the substrate was heated 200 nm as an insulating layer were formed on a quartz up to 550 C. in an argon atmosphere. As a result, most substrate main body. The resultant substrate was sub 55 of the film changed to polyperynaphthalene. A vi jected to a surface treatment in a y-aminopropyltrie olanthrene film having a film thickness of about 3 mm thoxysilane vapor phase. Perylenetetracarboxylic dian and a phenothiazine-TCNQ film having a film thickness hydride was deposited on the resultant substrate by the of about 30 nm were formed on the resultant substrate at vacuum deposition method, and the substrate was a substrate temperature of 50° C. by the vacuum deposi heated up to about 70 C. to cause a condensation reac tion method. In addition, a polyisobutylmethacrylate tion and re-dissociation of non-condensed molecules. film having a film thickness of 20 nm as an insulating Thereafter, a TTF-chloranil film having a film thick layer and an Au semitransparent electrode having a film ness of about 30 nm was formed. In addition, a thickness of 25 nm were formed on the phenothiazine polyisobutylmethacrylate film having a film thickness TCNQ film to manufacture an organic thin film ele of 20 nm as an insulating layer and an Au semitranspar 65 et. ent electrode having a film thickness of 20 nm were When no voltage was applied, the organic thin film formed on the TTF-chloranil film to manufacture an layer of this element exhibited an orange color. When a organic thin film element. voltage was applied to the organic thin film layer, the 5,155,566 15 16 color of the layer changed to dark red at a voltage of about 30 V. EXAMPLE 23 A perylenetetracarboxylic dianhydride film having a EXAMPLE 20 film thickness of 50 nm was formed on an Si substrate An ITO transparent electrode having a film thickness 5 main body, and an argon ion beam was radiated at an of 400 nm and an SiO2 film having a film thickness of acceleration energy of 3 MeV and a dose of 1616 cm-2 200 nm as an insulating layer were formed on a quartz in a vacuum. A violanthrene film having a film thick substrate main body. A co-deposition film consisting of ness of 2 nm and a phenothiazine-TCNQ film having a and 1,4-benzenedimethylchloride was formed film thickness of about 30 nm was formed on the resul on the resultant substrate, and a polycondensation film 10 tant substrate at a substrate temperature of 50° C. by the was formed in an argon atmosphere containing PCls at vacuum deposition method. a substrate temperature of 150° C. A violanthrene film When the film was observed by the SEM, it was having a film thickness of about 2 nm and a phenothia confirmed that a uniform continuous film in which the zine-TCNQ film having a film thickness of about 30 nm size of one domain reached 10 um was formed. In addi were formed on the resultant substrate at a substrate 15 tion, the orientation of the film was checked by the temperature of 50 C. by the vacuum deposition X-ray diffraction method. As a result, it was confirmed method. In addition, a polyisobutylmethacrylate film that all molecular planes of a phenothiazine-TCNQ having a film thickness of 20 nm as an insulating layer complex were oriented substantially parallel to the sub and an Au semitransparent electrode having a film strate surface. thickness of 25 nm were formed on the phenothiazine- 20 TCNQ film to manufacture an organic thin film ele EXAMPLE 24 et, An ITO transparent electrode having a film thickness When no voltage was applied, the organic thin film of 400 nm and an SiO2 film having a film thickness of layer of this element exhibited an orange color. When a 200 nm as an insulating layer were formed on a quartz voltage was applied to the organic thin film layer, the 25 substrate main body. A perylenetetracarboxylic dianhy color of the layer changed to dark red at a voltage of dride film having a film thickness of 50 nm was formed about 30 V. on the resultant substrate, and an argon ion beam was radiated at an acceleration energy of 3 MeV and a dose EXAMPLE 2. of 1616 cm-2 in a vacuum. A violanthrene film having a An ITO transparent electrode having a film thickness 30 film thickness of 2 nm and a phenothiazine-TCNQ film of 400 nm and an SiO2 film having a film thickness of having a film thickness of about 30 nm were formed on 200 nm as an insulating layer were formed on a quartz the resultant substrate at a substrate temperature of 50 substrate main body. A polyoxadiazole film was formed C. by the vacuum deposition method. In addition, a on the resultant substrate by a cast method, and the polyisobutylmethacrylate film having a film thickness substrate was subjected to a heat treatment at 900 C. in 35 of 20 nm as an insulating layer and an Au semitranspar a vacuum. A violanthrene film having a film thickness ent electrode having a film thickness of 25 nm were of about 2 nm and a phenothiazine-TCNQ film having a formed on the phenothiazine-TCNQ film to manufac film thickness of about 30 nm were formed on the resul ture an organic thin film element. tant substrate at a substrate temperature of 50 C. by the When no voltage was applied, the organic thin film vacuum deposition method. In addition, a polyisobutyl- 40 layer of this element exhibited an orange color. When a methacrylate film having a film thickness of 20 nm as an voltage was applied to the organic thin film layer, the insulating layer and an Au semitransparent electrode color of the layer changed to dark red at a voltage of having a film thickness of 25 nm were formed on the about 30 V. phenothiazine-TCNQ film to manufacture an organic thin film element. 45. EXAMPLE 25 When no voltage was applied, the organic thin film A diindenoperylene film having a film thickness of 50 layer of this element exhibited an orange color. When a nm was formed on an Si substrate main body, and an voltage was applied to the organic thin film layer, the electron beam was radiated at an acceleration voltage of color of the layer changed to dark red at a voltage of 20 kV. A violanthrene film having a film thickness of 2 about 30 V. SO nm and a phenothiazine-TCNQ film having a film thick ness of about 30 nm was formed on the resultant sub EXAMPLE 22 strate at a substrate temperature of 50° C. by the vac A perylenetetracarboxylic dianhydride film having a uum deposition method. film thickness of 50 nm was formed on an Si substrate When the film was observed by the SEM, it was main body, and an argon ion beam was radiated at an 55 confirmed that a uniform continuous film in which the acceleration energy of 3 MeV and a dose of 10.6 cm size of one domain reached 10 um was formed. In addi in a vacuum. A phenothiazine-TCNQ film having a film tion, the orientation of the film was checked the X-ray thickness of about 30 nm was formed on the resultant diffraction method. As a result, it was confirmed that all substrate at a substrate temperature of 50 C. by the molecular planes of a phenothiazine-TCNQ complex vacuum deposition method. 60 were oriented substantially parallel to the substrate When the film was observed by the SEM, it was surface. confirmed that a uniform continuous film in which the size of one domain reached 5 um was formed. In addi EXAMPLE 26 tion, the orientation of the film was checked by the An ITO transparent electrode having a film thickness X-ray diffraction method. As a result, it was confirmed 65 of 400 mn and an SiO2 film having a film thickness of that all molecular planes of a phenothiazine-TCNQ 200 nm as an insulating layer were formed on a quartz complex were oriented substantially parallel to the sub substrate main body. A diindenoperylene film having a strate surface. film thickness of 50 nm was formed on the resultant 5,155,566 17 18 substrate, and an electron beam was radiated at an ac 150 to 300 L or more while being heated up to 850 C., celeration voltage of 20 kV. A violanthrene film having thereby forming a carbon layer similar to graphite on its a film thickness of 2 nm and a phenothiazine-TCNQ surface. A TCNQ film having a film thickness of about film having a film thickness of about 30 nm were formed 100 nm was formed on the resultant substrate by the on the resultant substrate at a substrate temperature of 5 vacuum deposition method. 50 C. by the vacuum deposition method. In addition, a When the film was observed by the SEM, it was polyisobutylmethacrylate film having a film thickness confirmed that a uniform continuous film in which the of 20 nm as an insulating layer and an Au semitranspar size of one domain reached 10 um was formed. In addi ent electrode having a film thickness of 25 nm were tion, the orientation of the film was checked by the formed on the phenothiazine-TCNQ film to manufac 10 X-ray diffraction method. As a result, it was confirmed ture an organic thin film element. that molecular planes on one side of TCNQ crystal unit When no voltage was applied, the organic thin film cells having a herringbone structure were oriented par layer of this element exhibited an orange color. When a allel to the substrate surface. voltage was applied to the organic thin film layer, the color of the layer changed to dark red at a voltage of 15 EXAMPLE 30 about 30 V. An SiO2 film having a film thickness of 20 nm was formed on the surface of an Si substrate main body by a EXAMPLE 27 thermal oxidation method. A TiC film having a film An ITO transparent electrode having a film thickness thickness of 20 nm was formed on one surface of the of 400 nm and an SiO2 film having a film thickness of resultant substrate by the CVD method. The resultant 200 nm as an insulating layer were formed on a quartz substrate was exposed to ethylene gas for 150 to 300 L substrate main body. A perylenetetracarboxylic dianhy or more while being heated up to 850' C., thereby form dride film having a film thickness of 50 nm was formed ing a carbon layer similar to graphite on the TiC film. A on the resultant substrate, and an electron beam was methylphenazine-TCNQ film having a film thickness of radiated at an acceleration voltage of 20 kV to form a 25 about 30 nm was formed on the resultant substrate by rectangular pattern. The resultant substrate was dipped the vacuum deposition method. In addition, a in tetrahydrofuran to dissolve a film at a non-radiated polyisobutylmethacrylate film having a film thickness portion. A violanthrene film having a film thickness of of 20 nm as an insulating layer and an Au semitranspar 2 nm and a phenothiazine-TCNQ film having a film ent electrode having a film thickness of 25 nm were thickness of about 30 nm were formed on the resultant 30 formed on the methylphenazine-TCNQ film to manu substrate at a substrate temperature of 50° C. by the facture an organic thin film element. vacuum deposition method. In addition, a polyisobutyl In this organic thin film element, when no voltage methacrylate film having a film thickness of 20 nm as an was applied, a stretching vibration absorption peak of a insulating layer and an Au semitransparent electrode CN triple bonding of TCNQ according to a reflecting having a film thickness of 25 nm were formed on the 35 infrared spectrometry appeared at 2,200 cm. When a phenothianize-TCNQ film to manufacture an organic voltage was applied to the layer, the absorption peak thin film element. was shifted to 2,185 cm 1 at about 35 V. This is because In this organic thin film element, when no voltage the complex caused an ionic-neutral transition upon was applied, the organic thin film layer on the region on application of the voltage. which the perylenetetracarboxylic dianhydride film Additional advantages and modifications will readily was patterned exhibited an orange color. When a volt occur to those skilled in the art. Therefore, the inven age was applied to the organic thin film layer, the color tion in its broader aspects is not limited to the specific of the layer on the same region changed to dark red at details, and representative devices, shown and de a voltage of about 30 V. scribed herein. Accordingly, various modifications may 45 be made without departing from the spirit or scope of EXAMPLE 28 the general inventive concept as defined by the ap An Ni film having a film thickness of 50 nm was pended claims and their equivalents. formed on an Si substrate main body by an electron What is claimed is: beam deposition method. The resultant substrate was 1. An organic thin film element comprising: exposed to ethylene gas for 150 to 300 Langmuir (to be SO a substrate; and abbreviated to as L hereinafter) or more while being an organic thin film layer formed on said substrate heated up to 850 C., thereby forming a carbon layer and containing donor and acceptor molecules, similar to graphite on its surface, A TCNQ film having wherein said substrate comprises a substrate main a film thickness of about 100 nm was formed on the body and a layer consisting of polycyclic aromatic resultant substrate by the vacuum deposition method. group molecules or a derivative thereof on a sur When the film was observed by the SEM, it was face of the substrate main body. confirmed that a uniform continuous film in which the 2. An element according to claim 1, wherein said size of one domain reached 10 um was formed. In addi organic thin film layer containing donor and acceptor tion, the orientation of the film was checked by the molecules consists of a mixed stacked charge-transfer X-ray diffraction method. As a result, it was confirmed complex. that molecular planes on one side of TCNQ crystal unit 3. An element according to claim 1, wherein said cells having a herringbone structure were oriented par layer consisting of polycyclic aromatic group molecules allel to the substrate surface. or a derivative thereof is formed by a vacuum deposi EXAMPLE 29 tion method. 65 4. An element according to claim 1, wherein said A TiC film having a film thickness of 20 nm was layer consisting of polycyclic aromatic group molecules formed on an Si substrate main body by a CVD method. or a derivative thereof is formed by an adsorption The resultant substrate was exposed to ethylene gas for method. 5,155,566 19 20 5. An element according to claim 1, wherein said 10. An organic thin film element comprising: a sub layer consisting of a polycyclic aromatic group mole strate; and an organic thin film layer formed on said substrate cules or a derivative thereof is formed by a and containing donor and acceptor molecules, Langmuir-Blodgett method. wherein said substrate comprises a substrate main 6. An element according to claim 1, wherein said body and a carbon layer having a graphite struc layer consisting of polycyclic aromatic group molecules ture on a surface of the substrate main body. or a derivative thereof is formed via a chemical bond 11. An element according to claim 10, wherein said ing. organic thin film layer containing donor and acceptor 7. An element according to claim 1, wherein said O molecules consists of a mixed stacked charge-transfer layer consisting of polycyclic aromatic group molecules complex. 12. An element according to claim 10, wherein said or a derivative thereof is formed by heat polymeriza carbon layer having a graphite structure is formed by tion. thermally decomposing hydrocarbon adsorbed on the 8. An element according to claim 1, wherein said 5 surface of said substrate main body. substrate is constituted by a transparent substrate main 13. An element according to claim 10, wherein said body, a transparent electrode, an insulating layer, and a substrate is constituted by a transparent substrate main layer consisting of polycyclic aromatic group molecules body, a transparent electrode, an insulating layer, and a or a derivative thereof, and has a structure in which an carbon layer having a graphite structure, and has a structure in which an organic thin film layer, an insulat organic thin film, an insulating layer, and a back elec ing layer, and a back electrode are sequentially formed trode are sequentially formed thereon, and exhibits a thereon, and exhibits a display function. display function. 14. An element according to claim 13, wherein said 9. An element according to claim 8, wherein said organic thin film layer has a superlattice structure and organic thin film layer has a superlattice structure and 25 exhibits a multi-value function. exhibits a multi-value function. k X

35

45

SO

55

65