DOCSLIB.ORG

Electrical Properties of Multi P-N Junction Devices

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrical Properties of Multi P-N Junction Devices IEEE TRANSACTIONSIEEE ON ED-29,ELECTRONDEVICES,VOL. NO. 6, JUNE 1982 977 [ 151 J. G. Nash and J. W. Holm-Kennedy, “Effect of electron-electron [23] P. N. Swartztrauber and R. Sweet, “Efficient fortran subprograms scattering on hot-electron repopulation in n-Si at 77”K,” Phys. forthe solution of elliptic partial differential equations,” Na- Rev. B, vol. 16, p. 2834, 1977. tionalCenter for Atmospheric Res.,Tech. NoteTN/IA-109, [ 161 J V. Faricelli, “Physics of large-signal response of short-channel 1975. MESFET’s,” M.S. thesis, Cornell Univ., Ithaca, NY, 1980. [24] R. W. Hockney,“POT4-A fast direct Poisson solverfor the [ 171 K. Blotekjaer, “Transport equations for two-valleysemiconduc- rectangle allowing some mixed boundary conditions and internal tors,’’ IEEE Trans. Electron Devices, vol. ED-17, p. 38, 1970. electrodes,” IBM Res. Rep., RC-2870. [18] M. S. Shur,“Influence of non-uniformfield distribution on [25] D. L. Scharfetter and H.K. Gummel, “Large signal analysis of a frequency limits of GaAs field-effect transistors,” Electron Lett., siliconRead diodeoscillator,” IEEE Trans. ElectronDevices, vol. 12, p. 615, 1976. VO~.ED-16, p. 64, 1969. [ 191 C. Jacoboni et al., “A review of some charge transport properties [26] M. Reiser,“Large scale numerical simulation in semiconductor of silicon,” Solid-state Electron., vol. 20, p. 77, 1977. device modeling,” Computing Methods in Applied Mathematics [20] P. M. Smith, M. Inoue,and J. Frey,“Electron velocity in Si and Engineering, vol. 1, p. 17. and GaAs at very high electric fields,” J. Appl. Phys., vol. 37, p. [27] J. Ruch, “Electron dynamics in short channel field effect transis- 797, 1980. tors,” IEEE Trans. Electron Devices, vol. ED-19, p. 652, 1912. [21] T. J. Maloney, “Non-equilibrium electron transport in compound [28] R. C. Eden and B. M. Welch, “GaAs digital integrated circuits for semiconductors,” Ph.D, dissertation,Cornell Univ., Ithaca, NY, ultra-high speed LSI/VLSI,” in VLSI: Fundamentals and Applica- 1977. tions, D. F. Barbe, Ed. Berlin, Germany: Springer-Verlag, 1980. [22] S. Kratzer,“Computer simulations of electrontransport in [29] T. Wada and J. Frey, “Physicalbasis of short-channel MESFET GaAs,” M.S. thesis, Cornell Univ., Ithaca, NY, 1978. operation,”IEEE J. Solid-State Circuits, vol. SC-14, p. 398,1979. Electrical Properties of Multi p-n Junction Devices JOSEPH KATZ, SHLOMO MARGALIT, AND AMNON YARIV, FELLOW, IEEE Abstract-The electrical properties of multi p-n junction devices are devices as injection lasers has also been reported, but no analy- analyzed. It is found that this type of device possesses bistable charac- sisof the electrical properties of such structures has been teristicssimilar tothat of aShockley diode and thus provides an published. alternativerealization of devices forswitching applications. The in- herently greater current gains involved in the operations of such a de- This paper analyzes the electrical properties of semiconduc- viceyield in princ,iplehigher breakover voltages andhigher holding tor devices consisting of many layers of alternating p- and currents.Furthermore, the incorporation of heterostructuresin this n-type.Incorporation of heterostructures in these devices device introduces a new degree of freedom in tailoring their switching makes the design of their characteristics more flexible due to characteristics.Multi p-n heterojunction devices operatingas SCR the introduction of the additional degreeof freedom of the lasers were fabricated, and the experimental results are presented, energy band gap difference. It is foundthat such devices provide an alternative for realizing bistable switching charac- I. INTRODUCTION teristics. Compared to switching devices fabricated from sili- INCE THEIR introduction,the Shockleydiode [l] and con, GaAsdevices are lesssensitive to high temperatures Sother related deviceshave foundmany applications in because of their larger band gap and are inherently faster be- switching and regulating circuits [2] . Recently the operation cause of their shorter carrier lifetime. Since the common-base of Shockley diodes which function also as AlGaAs injection current gainof the transistors that model thesedevices (see lasers has been demonstrated [3]. Operation of both homo- next section) is distributed among all the regions of the struc- structure [4] and heterostructure [5] multi p-n GaAs-GaAlAs ture,different switching conditions are obtained. Mainly it is foundthat it takes more gain to perform the switching, Manuscriptreceived November 16,1981; revised February 3, 1982. which results in an increase in the breakover voltages and in Thiswork was supported in part by the Jet Propulsion Laboratory, the holding currents. California Institute of Technology, under NASA Contract NAS7-100, the Office of Naval Research and the National Science Foundation. The outline of this paper is as follows: In Section 11, a quali- J. Katz is with the Jet Propulsion Laboratory, California Institute of tative analysisof multi p-n devices,based on an extended Technology, Pasadena, CA 91109. transistormodel, is carried out. The results of this analysis S. Margalit and A. Yariv are with the Department of Electrical Engi- neeringand Applied Physics, California Institute of Technology, show that such structures have bistable characteristics similar Pasadena. CA 9 1125. to those of aShockley diode. Sections I11 and IV analyze 0018-9383/82/0600-0977$00.75 0 1982 IEEE 978 IEEE TRANSACTIONS ON ELECTRON DEVICES, VQL. ED-29, NO. 6, JUNE 1982 (a) (b) (c) Fig. 1. Transistor model of a (p-n), device. (a) Schematic structure of the device. (b) Decomposition of the device into individual transis- tors. (c) Equivalent circuit of the device. quantitatively the device in its two stable states: the forward ing matrix equation. A is given by blocking (“OFF ”) and the forward conducting (“ON”) states, r- - 1000 000 00-100 respectively, Finally, Section V describes the fabrication pro- cedure and the experimental results of several types of such 1-1-10 000 000 00 devices, and compares the experimental results with the theo- -CY,OlO 010 000 00 retical calculations. 0-100 010 00000 11. MODIFIED TRANSISTORMODEL FOR 0 001-1-10 000 00 MULTI p-n STRUCTURES 0 OO-a2010 000 00 Consider a structure consisting of 2m layers of alternating 0 0-10101 010 00 p- and n-type, which is denoted by (p-n),. In this structure the ith junction separates the ithand the (it 1)th layer. 0 000 001-1-10 00 By a directextension of thetwo-transistor model for the 0 000 00-cu3010 00 SCR, one can analyze the structure using a more complicated 0 00-1 000-100 01 transistor network. An example of a (p-n), structure is shown in Fig. 1. Generally, it takes a 2 X (m - 1) transistor network 0 000 000 001-1-1 to describe a (p-n), structure. The 3 X 2 X (m - 1) equations 0 000 000 OO-a,Ol- needed to describe thenetwork (three equations for each transistor) are (3) and Z and Idfive are given by IBj t ICj = IEi, i= 1,2,.,2(m - 1) (la) 7-l I-- -I Ici=aiI~i+Icoi, i=1,2;..,2(m- 1) (lb) IE 1 -CIGi ICi =IB,i-1 +IE,i-2 +IG,i-1 9 i=2,4,6;**,2(m- 1) (IC) IB1 0 IC1 IC0 1 IEi = -IB,i-lIC,i-2 2 IG,i-l > i=3,5,7;-.,2m- 3 (Id) IE2 IG 1 IB2 0 I = IC2 . Idrive = IC702 IE3 IG2 where the transistors are assumed to be initially in the cutoff 0 or active region(i.e., the deviceis in the forward blocking IB3 state), Icoi is the collector to base reverse saturation current IC3 IC03 of the ith transistor, ai is the common-basecurrent gain of IE4 IG 3 the ith transistor, and IG~is the current generated at the ith 0 gate of the device. The set of equations (1) can be cast in a I84 matrix form IC4- - IC04 4 Equation (2) can be solved for la = IE~with {ai} as a set of For example, the (p-n), structure is described by the follow- parameters. The particular case where IA approaches infinity KATZ et al.: MULTI p-n JUNCTION DEVICES 979 + P Anode + P Anode ”O 7 JI - x El a8 ff’ JZ a, / J3 P‘ 0.6 - b//’ / / /’ a 1’ I c ,p’ 0.4 - ,/ I‘ n‘ ’ / 6’ -bCothode -6 Cathode // (a) (b) Fig. 3. Comparisonbetween the generic characteristics of (p-n), and (p-n)zdevices. (a) (p-n), device. (b)Corresponding (p-n)~device I’ / (regular Shockley diode). IIIIII 23456789 electrical characteristics, Fig.3(a) depictsthe device in the rn Fig. 2. Common base current gain (a)for switching of a (p-n), device forward blocking (“OFF”) state. The crosshatched areas versus m. (a) All the transistors are identical (ai = 01). (b) All the odd represent the depletion regions of the reverse biased junctions (or all the even) numbered transistors in the model have 01 = 0.95. (J2 and J4). The junction J, is, in principle, forward biased. Shown is a neededfrom the other transistors for switching. (c) Same as in (b), but with agiven AI of 0.99. However, since the current that flows through the deviceis very small, there is also a very small voltage drop in the region (i.e., the determinant of A equals zero) indicates theswitching between Jz and J4. Since a region with virtually no current condition.Inspection of thematrix A in (2) shows the and voltage has a little effect on the device, to the external following: world the device appears basically as if‘it had thestructure 1) (p-n)m structures, with m 2 2, cannot possess more than depicted in Fig. 3(b), which is a device. Inthe forward twostable states. This is deducedfrom thefact that for a conducting (“ON”) state, all the internal regions in the (p-n), given structure, only one set of {acui},at most, yields 1, +.
Load more

Recommended publications
  • Thyristors.Pdf
    THYRISTORS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. Thyristors Thyristors are a class of semiconductor devices characterized by 4-layers of alternating p and n material. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications. Some thyristors and their symbols are (a) 4-layer diode (b) SCR (c) Diac (d) Triac (e) SCS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The 4-layer diode (or Shockley diode) is a type of thyristor that acts something like an ordinary diode but conducts in the forward direction only after a certain anode to cathode voltage called the forward-breakover voltage is reached. The basic construction of a 4-layer diode and its schematic symbol are shown The 4-layer diode has two leads, labeled the anode (A) and the Anode (A) A cathode (K). p 1 n The symbol reminds you that it acts 2 p like a diode. It does not conduct 3 when it is reverse-biased. n Cathode (K) K Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The concept of 4-layer devices is usually shown as an equivalent circuit of a pnp and an npn transistor. Ideally, these devices would not conduct, but when forward biased, if there is sufficient leakage current in the upper pnp device, it can act as base current to the lower npn device causing it to conduct and bringing both transistors into saturation.
    [Show full text]
  • 68 Chapter 9: Thyristors Thyristors Thyristors Are a Class Of
    Electronic Devices Chapter 9: Thyristors Thyristors Thyristors are a class of semiconductor devices characterized by 4-layers of alternating p- and n-material. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications such as lamp dimmers, motor speed controls, ignition systems, charging circuits, etc. Thyristors include Shockley diode, silicon-controlled rectifier (SCR), diac and triac. They stay on once they are triggered, and will go off only if current is too low or when triggered off. Some thyristors and their symbols are in figure 1. (a) 4-layer diode (b) SCR (c) Diac (d) Triac (e) SCS Figure 1 Shockley Diode The 4-layer diode (or Shockley diode) is a type of thyristor that acts something like an ordinary diode but conducts in the forward direction only after a certain anode to cathode voltage called the forward-breakover voltage is reached. The basic construction of a 4-layer diode and its schematic symbol are shown in Figure 2. Figure 2: The 4-layer diode. The 4-layer diode has two leads, labeled the anode (A) and the cathode (K). The symbol reminds you that it acts like a diode. It does not conduct when it is reverse-biased. The concept of 4-layer devices is usually shown as an equivalent circuit of a pnp and an npn transistor. Ideally, these devices would not conduct, but when forward biased, if there is sufficient leakage current in the upper pnp device, it can act as base current to the lower npn device causing it to conduct and bringing both transistors into saturation 68 Assist.
    [Show full text]
  • The Transistor
    Chapter 1 The Transistor The searchfor solid-stateamplification led to the inventionof the transistor. It was immediatelyrecognized that majorefforts would be neededto understand transistorphenomena and to bring a developedsemiconductor technology to the marketplace.There followed a periodof intenseresearch and development, duringwhich manyproblems of devicedesign and fabrication, impurity control, reliability,cost, and manufacturabilitywere solved.An electronicsrevolution resulted,ushering in the eraof transistorradios and economicdigital computers, alongwith telecommunicationssystems that hadgreatly improved performance and that were lower in cost. The revolutioncaused by the transistoralso laid the foundationfor the next stage of electronicstechnology-that of silicon integratedcircuits, which promised to makeavailable to a massmarket infinitely more complexmemory and logicfunctions that could be organizedwith the aid of softwareinto powerfulcommunications systems. I. INVENTION OF THE TRANSISTOR 1.1 Research Leading to the Invention As World War II was drawing to an end, the research management of Bell Laboratories, led by then Vice President M. J. Kelly (later president of Bell Laboratories), was formulating plans for organizing its postwar basic research activities. Solid-state physics, physical electronics, and mi­ crowave high-frequency physics were especially to be emphasized. Within the solid-state domain, the decision was made to commit major research talent to semiconductors. The purpose of this research activity, according
    [Show full text]
  • SHOCKLEY, WILLIAM BRADFORD Els at Which Electrons Can (Or Cannot) Flow Through a Crys- (B
    ndsbv6_S2 9/27/07 4:14 PM Page 437 Shockley Shockley Greenstein, Jesse, and Rudolph Minkowski. “The Crab Nebula John Bardeen and Walter Brattain, he invented the tran- as a Radio Source.” Astrophysical Journal 118 (1953): 1–15. sistor, sharing the 1956 Nobel Prize in Physics with them McCutcheon, Robert A. “Stalin’s Purge of Soviet Astronomers.” for this achievement. In particular, he conceived the junc- Sky & Telescope 78, no. 4 (October 1989): 352–357. tion transistor, a solid-state amplifier and switch that was Minkowski, Rudolph. “The Crab Nebula.” Astrophysical Journal commercialized during the 1950s and eventually led to 96 (1942): 199–213. Reprinted with commentary in A the microelectronics revolution. In founding the Shockley Source Book in Astronomy & Astrophysics, edited by Kenneth Semiconductor Laboratory in California, he catalyzed the R. Lang and Owen Gingerich. Cambridge, MA: Harvard University Press, 1979. emergence of Silicon Valley as the epicenter of the global semiconductor industry. As a Stanford University profes- Moroz, Vasilii I. “A Short Story about the Doctor.” Astrophysics & Space Science B252 (1997): 1–2, 5–14. sor during the last two decades of his life, he espoused Oort, Jan H. “The Crab Nebula.” Scientific American 196, no. 3 controversial views on race and intelligence that brought (March 1957): 52–60. On Shklovskii’s hypothesis of him substantial public attention and notoriety. synchrotron radiation as the source of its emission. Salomonovich, A. E. “The First Steps of Soviet Radio Early Years. Shockley was born in London on 13 Febru- Astronomy.” In The Early Years of Radio Astronomy: Reflections ary 1910, the only son of William Hillman Shockley, a Fifty Years after Jansky’s Discovery, edited by W.
    [Show full text]
  • Oral History of Hans Queisser
    Oral History of Hans Queisser Interviewed by: Craig Addison Recorded: February 27, 2006 Mountain View, California CHM Reference number: X3453.2006 © 2006 Computer History Museum Oral History of Hans Queisser Craig Addison: I am Craig Addison from SEMI. I am with Hans Queisser. We’re at the Computer History Museum in Mountain View, California, and today’s date is February 27, 2006. Hans, could we start off at the beginning and have you talk about where you were brought up and your educational background. Hans Queisser: Yes. I was born in Berlin, Germany, in 1931. My father was an engineer with the Siemen’s Company. And at that time, Siemen’s Town in Berlin was really a center of high technology. So I got very much influenced by my father, by our neighbors, in technical things. And I survived the Dresden air raid just barely in 1945 when I was 14 years old. And the end of the war was not easy, you can imagine. My father had to work for a Russian government agency. Times were tough. And my belief that I should enter a scientific field was strengthened by the fact that I could see that people who had a technical background and who had something to say, were treated very nicely by both the Russians and the Americans. But people who had nothing of value were treated rather badly. So that was my belief that in order to survive you had to have something that was a skill. And I wanted to go into physics, which I did.
    [Show full text]
  • The Silicon Controlled Rectifier (SCR)
    The silicon controlled rectifier (SCR) Shockley diodes are curious devices, but rather limited in application. Their usefulness may be expanded, however, by equipping them with another means of latching. In doing so, each becomes true amplifying devices (if only in an on/off mode), and we refer to these as silicon-controlled rectifiers, or SCRs. The progression from Shockley diode to SCR is achieved with one small addition, actually nothing more than a third wire connection to the existing PNPN structure: (Figure below) The Silicon-Controlled Rectifier (SCR) If an SCR's gate is left floating (disconnected), it behaves exactly as a Shockley diode. It may be latched by breakover voltage or by exceeding the critical rate of voltage rise between anode and cathode, just as with the Shockley diode. Dropout is accomplished by reducing current until one or both internal transistors fall into cutoff mode, also like the Shockley diode. However, because the gate terminal connects directly to the base of the lower transistor, it may be used as an alternative means to latch the SCR. By applying a small voltage between gate and cathode, the lower transistor will be forced on by the resulting base current, which will cause the upper transistor to conduct, which then supplies the lower transistor's base with current so that it no longer needs to be activated by a gate voltage. The necessary gate current to initiate latch-up, of course, will be much lower than the current through the SCR from cathode to anode, so the SCR does achieve a measure of amplification.
    [Show full text]
  • Silicon-Controlled Rectifiers
    Component Theory SCRs 1 Silicon-Controlled Rectifiers Our exploration of thyristors begins with a device called the four-layer diode, also known as a PNPN diode, or a Shockley diode after its inventor, William Shockley. This is not to be confused with a Schottky diode, that two-layer metal-semiconductor device known for its high switching speed. A crude illustration of the Shockley diode, often seen in textbooks, is a four-layer sandwich of P-N-P-N semiconductor material. 2 Silicon-Controlled Rectifiers Shockley or 4-layer diode Transistor equivalent of Shockley diode 3 Silicon-Controlled Rectifiers A silicon-controlled rectifier (or semiconductor- controlled rectifier) is a four-layer solid state device that controls current. The name "silicon controlled rectifier" or SCR is General Electric's trade name for a type of thyristor. The SCR was developed by a team of power engineers led by Gordon Hall and commercialized by Frank W. "Bill" Gutzwiller in 1957. 4 Silicon-Controlled Rectifiers Construction of SCR An SCR consists of four layers of alternating P and N type semiconductor materials. Silicon is used as the intrinsic semiconductor, to which the proper dopants are added. The junctions are either diffused or alloyed. The planar construction is used for low power SCRs (and all the junctions are diffused). The mesa type construction is used for high power SCRs. In this case, junction J2 is obtained by the diffusion method and then the outer two layers are alloyed to it, since the PNPN pellet is required to handle large currents. 5 Silicon-Controlled Rectifiers It is properly braced with tungsten plates to provide greater mechanical strength.
    [Show full text]
  • Physics of Semiconductor Devices – Chapter 4: Thyristors
    Physics of Semiconductor Devices – Chapter 4: Thyristors • 4.1: Introduction • 4.2: Basic characteristics • 4.3: Shockley diode and three-terminal thyristor • 4.4: Related power thyristors • 4.5: Diac and triac • 4.6: Unijunction transistor and trigger thyristor • 4.7: Field-controlled thyristor Student presentations 2006-04-05 Ulf Lindefelt, ITM, MIUN 1 4.1: Introduction • The word “thyristor” comes from the word “gas thyratron”, which was an old- fashioned gas-based device having roughly the same electrical characteristics as the semiconductor-based thyristor. • Basically, a thyristor is a switch which has a forward high impedance low current OFF state and a forward low impedance high current ON state. • In general terms a thyristor is a semiconductor device of the type pnpn or npnp, i.e., a four-layer device. A two-terminal thyristor is often called a Shockley diode. • A theoretical description of how a thyrisor works was developed by Moll et al. (J.L. Moll, M. Tanenbaum, J.M. „Goldley and N. Holonyak, “p-n-p-n Transistor Switches”, Proc. IRE 44, 1174 (1956)). • It is typically used in the high voltage, high current regime (typically 10 kV, 5kA) 2006-04-05 Ulf Lindefelt, ITM, MIUN 2 4.2: Basic characteristics Shockley diode Fig.2a: Typical doping profiles in Thyristor a thyristor In these lectures I use the term „thyristor‟ to denote also the „Shockley diode‟ 2006-04-05 Ulf Lindefelt, ITM, MIUN 3 4.2: Basic characteristics • (0)-(1): Forward blocking (or OFF) state • (1): Forward breakover (at breakover voltage VBF and switching current
    [Show full text]
  • Pn JUNCTION DEVICES and LIGHT EMITTING DIODES
    pn Junction Devices (© 2001 S.O. Kasap) 1 An e-Booklet pn JUNCTION DEVICES AND LIGHT EMITTING DIODES Safa Kasap Electrical Engineering Department University of Saskatchewan Canada “We consider alloyed or point contact junctions on n-type GaP. Then the light emitted with forward bias has a spectrum which is a comparatively narrow band, the position of the band depending on the impurities present in the GaP.” J.W. Allen and P.E. Gibbons (1959)1 William Shockley, (seated), John Bardeen (left) and Walter Brattain (right) invented the transistor at Bell Labs and thereby ushered in a new era of semiconductor devices. The three inventors shared the Nobel prize in 1956. (Courtesy of Bell Laboratories.) 1. pn Junction Principles 1. 1. Open Circuit Consider what happens when one side of a sample of Si is doped n-type and the other p-type as shown in Figure 1 (a). Assume that there is an abrupt discontinuity between the p and n regions which we call the metallurgical junction, M in Figure 1 (a), where the fixed (immobile) ionized donors and the free electrons (in the conduction band, CB) in the n-region and fixed ionized acceptors and holes (in the valence band, VB) in the p-region are also shown. 1 Allen and Gibbons (talking about their invention of the LED) in “Breakdown and light emission in gallium phosphide diodes”, Journal of Electronics, Vol. 7, No. 6, p. 518, December 1959. pn Junction Devices (© 2001 S.O. Kasap) 2 An e-Booklet Due to the hole concentration gradient from the p-side, where p = ppo, to the n-side where p = pno, holes diffuse towards the right and enter the n-region and recombine with the electrons (majority carriers) in this region.
    [Show full text]
  • Jonathan Hoppe Historic Collection
    Mr. Jonathan Hoppe TRANSISTOR MUSEUM DONATION March 2014 Historic 1950s Germanium Computer Transistors PROTOTYPE AND LIMITED PRODUCTION DEVICES FROM THE EARLY 1950s DONATION COMMENTS: “I have in my possession a box with a number of early transistors. My grandfather worked as a Co-op for the Burroughs corporation in the early 1950s and one of his first projects was taking test data from these transistors to document their performance parameters. Some of the tests were recorded on film (stills of the o-scope screen) and are in the box as well. Now if these were commonplace ones I would not be emailing you, but these are far from commonplace. There are quite a few experimental ones, which I do not see listed on your page. I would be more than happy to donate an example of the ones you do not have.” CURATOR’S COMMENTS: The early 1950s, when Jonathan Hoppe’s grandfather worked as a Co-op at the Burroughs Corporation, were an exciting time in the history of transistor development. The first commercial transistors were just becoming available, and computer manufacturing companies were eager to evaluate the performance of these crude devices for use in digital circuits. This historic collection provides an unparalleled view into the state of the art from the first days of transistor technology. The Transistor Museum wishes to thank Mr. Hoppe for this generous and historic donation. The following pages provide detailed photos and technical descriptions of many of the transistors from the Hoppe collection. We’ll also include links and references for further information on these historic device types.
    [Show full text]
  • Thyristors This Worksheet and All Related Files Are Licensed Under The
    Thyristors This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/, or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. The terms and conditions of this license allow for free copying, distribution, and/or modification of all licensed works by the general public. Resources and methods for learning about these subjects (list a few here, in preparation for your research): 1 Questions Question 1 All thyristor devices exhibit the property of hysteresis. From an electrical perspective, what is ”hysteresis”? How does this behavior differ from that of ”normal” active semiconductor components such as bipolar or field-effect transistors? file 01089 Question 2 What is required to make a Shockley diode or DIAC begin conducting current? What condition(s) have to be met in order for electrical conduction to occur through one of these devices? Also, explain what must be done to stop the flow of electric current through a Shockley diode or a DIAC. file 01090 Question 3 Silicon-controlled rectifiers (SCRs) may be modeled by the following transistor circuit. Explain how this circuit functions, in the presence of and absence of a ”triggering” voltage pulse at the gate terminal: Load Anode Gate Cathode file 01088 2 Question 4 Shown here is an illustration of a large ”stud mount” type of SCR, where the body is threaded so as to be fastened to a metal base like a bolt threads into a nut: With no test instrument other than a simple continuity tester (battery and light bulb connected in series, with two test leads), how could you determine the identities of the three terminals on this SCR? Hint: The threaded metal base of the SCR constitutes one of the three terminals.
    [Show full text]
  • Semiconductor Diodes
    Semiconductor diodes A modern semiconductor diode is made of a crystal of semiconductor like silicon that has impurities added to it to create a region on one side that contains negative charge carriers (electrons), called n-type semiconductor, and a region on the other side that contains positive charge carriers (holes), called p-type semiconductor. The diode's terminals are attached to each of these regions. The boundary within the crystal between these two regions, called a PN junction, is where the action of the diode takes place. The crystal conducts “electron current” in a direction from the n-type side (called the cathode), to the p-type side (called the anode), but not in the opposite direction or for those familiar with “conventional current” in a direction from the p-type side (called the anode) to the n-type side (called the cathode), but not in the opposite direction. Another type of semiconductor diode, the Schottky diode, is formed from the contact between a metal and a semiconductor rather than by a p-n junction. Rectifier A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum tube diodes, mercury arc valves, and other components. A device which performs the opposite function (converting DC to AC) is known as an inverter. When only one diode is used to rectify AC (by blocking the negative or positive portion of the waveform), the difference between the term diode and the term rectifier is merely one of usage, i.e., the term rectifier describes a diode that is being used to convert AC to DC.
    [Show full text]