DOCSLIB.ORG

The Effect of Trimethylaluminum Flow Rate on the Structure and Optical Properties of Alingan Quaternary Epilayers

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Effect of Trimethylaluminum Flow Rate on the Structure and Optical Properties of Alingan Quaternary Epilayers crystals Article The Effect of Trimethylaluminum Flow Rate on the Structure and Optical Properties of AlInGaN Quaternary Epilayers Dongbo Wang 1, Gang Liu 2,*, Shujie Jiao 1,*, Lingping Kong 2, Teren Liu 1, Tong Liu 3, Jinzhong Wang 1, Fengyun Guo 1, Chunyang Luan 1 and Zhenghao Li 1 1 Department of Opto-Electronic Information Science, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China; [email protected] (D.W.); [email protected] (T.L.); [email protected] (J.W.); [email protected] (F.G.); [email protected] (C.L.); [email protected] (Z.L.) 2 Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China; [email protected] 3 Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123, China; [email protected] * Correspondence: [email protected] (G.L.); [email protected] (S.J.); Tel./Fax: +86-451-8641-8745 (S.J.) Academic Editors: Alain Largeteau, Mythili Prakasam and Helmut Cölfen Received: 27 November 2016; Accepted: 22 February 2017; Published: 6 March 2017 Abstract: In this work, a series of quaternary AlxInyGa1−x−yN thin films have been successfully achieved using metal organic chemical vapor deposition (MOCVD) method with adjustable trimethylaluminum (TMA) flows. Surface morphology and optical properties of AlxInyGa1−x−yN films have been evaluated. The indium segregation effect on the enhancement of UV luminescence emission in AlxInyGa1-x-yN films with increasing TMA flows was investigated. Our results shed some lights on future optical materials design and LED/LD applications. Keywords: trimethylaluminum flows; AlInGaN alloys; photoluminescence 1. Introduction In the past decades, GaN-based ternary alloys have made significant progress in blue, green, and ultraviolet (UV) light emitting diodes (LEDs) and laser diodes (LDs) [1–3]. Despite the great progress that has been made, the commercial InGaN/GaN blue LEDs still suffered from some fundamental problems related to the basic material properties. Even though InGaN-based blue LEDs are less sensitive to crystalline quality because of the carrier localization effect induced by alloy composition fluctuation [4], the piezoelectric polarization effect induced by the strain between barrier and well has been considered as one of the reasons of efficiency droop effect [5,6]. Meanwhile, AlGaN-based UV LEDs combined with RGB phosphors have also been proposed to avoid the color rendering problems in white LED made by blue LED with YAG phosphors. However, because of low doping efficiency and poor crystal quality, highly efficient AlGaN-based UV LEDs are still hard to achieve. In order to solve these problems in ternary InGaN- and AlGaN-based devices, several researchers have recently grown quaternary AlInGaN films [7,8]. Quaternary AlInGaN films are considered to have the potential to overcome the above shortcomings of ternary alloys, since AlInGaN films can be grown by independently controlling the lattice constant and the band gap by adjusting the composition [9]. Therefore, AlInGaN attracts much attention as a candidate material for high efficiency LEDs or LDs. The growth of AlInGaN has been proven to be extremely challenging, attributed to the large difference in the growth condition between InN, GaN, and AlN [10,11]. Crystals 2017, 7, 69; doi:10.3390/cryst7030069 www.mdpi.com/journal/crystals Crystals 2017, 7, x FOR PEER REVIEW 2 o f 8 Crystalschallenging2017, 7, 69attributed to the large difference in the growth condition between InN, GaN, and 2AlN of 8 [10,11]. Recently, Yu et al. [12] reported the optical and electrical properties of AlInGaN with various Recently, Yu et al. [12] reported the optical and electrical properties of AlInGaN with various trimethylindium (TMIn) molar rates. Fu et al. [13] reported the effect of trimethylgallium (TMGa) flow trimethylindium (TMIn) molar rates. Fu et al. [13] reported the effect of trimethylgallium (TMGa) rate on the optoelectrical characteristics of AlInGaN. However, there are few reports available about flow rate on the optoelectrical characteristics of AlInGaN. However, there are few reports available AlInGaN structure and optical properties with varied trimethylaluminum (TMA) flow rate. Because about AlInGaN structure and optical properties with varied trimethylaluminum (TMA) flow rate. of the large lattice mismatch between the InN and AlN, there is a great increasing trend in Because of the large lattice mismatch between the InN and AlN, there is a great increasing trend in compositional disorders with increasing Al/In content, and their influence on the optical properties compositional disorders with increasing Al/In content, and their influence on the optical properties of of AlxInyGa1−x−yN quaternary alloys arise as a result [14,15]. It is important to know the influence of AlxInyGa1−x−yN quaternary alloys arise as a result [14,15]. It is important to know the influence of Al Al content on the properties of AlInGaN quaternary alloys when Al atoms are added in the film content on the properties of AlInGaN quaternary alloys when Al atoms are added in the film layer to layer to adjust the band gap of the quaternary. adjust the band gap of the quaternary. In this manuscript, we reported AlInGaN/GaN heterostructure grown by MOCV D with In this manuscript, we reported AlInGaN/GaN heterostructure grown by MOCVD with varying varying TMA flow rate. Structural and optical properties versus TMA flow rate in AlInGaN were TMA flow rate. Structural and optical properties versus TMA flow rate in AlInGaN were systematically systematically investigated. The purpose of this article is to experimentally study the influence of investigated. The purpose of this article is to experimentally study the influence of TMA flow rate TMA flow rate on the AlInGaN quaternary, which will be highly useful for optimizing growth of on the AlInGaN quaternary, which will be highly useful for optimizing growth of AlInGaN- and AlInGaN- and AlInGaN- based device application. AlInGaN- based device application. 2. Results Figure 11aa showsshows (0004)(0004) !ω--22θθ scans of AlInGaN/GaN samples samples 1 1to to 4. 4. The The diffraction diffraction peaks peaks at at 0 0arcsec arcsec originated originated from from the the GaN GaN buffer buffer layers. layers. For For all all the the sampl samples,es, the the diffraction peaks from thethe quaternary AlInGaNAlInGaN thin filmsfilms shiftedshifted to thethe rightright sideside withwith increasingincreasing TMATMA flowflow rate.rate. ThisThis waswas ascribed toto thethe increaseincrease of of the the lattice lattice constant constant due due to to the the increase increase in Alin Al incorporation. incorporation. For For sample sample 1, the 1, AlInGaNthe AlInGaN and and GaN GaN peaks pea were ks were overlapped, overlapped, which which means means that that the lattices the lattice matchs match along along the c-axes the c-axes [15]. For[15] sample. For sample 4, without 4, without any Al any incorporation, Al incorporation, the diffraction the diffraction peak peak originated originated from InGaN.from InGaN. Figure 1. XRDXRD spectraspectra of of Al AlxInxInyyGaGa11−−x−−yN/GaNyN/GaN laye layers rs with with diffe different re nt trime trimethylaluminum thylaluminum ( (TMA)TMA) flow flow rate:rate: ((aa)) (0004) ω!--22θθ scan; ((bb)) 22θθ scan.s c a n. Figure1 1bb showsshows 2 2θθ scans scans ofof AlInGaN/GaNAlInGaN/GaN samples. samples. The The peaks located at 34.5 ◦° originated from the GaNGaN buffer buffer layers. layers. The The shoulder shoulder peaks peaks at the at right the sideright of side GaN of peaks GaN originated peaks originated from the AlInGaNfrom the layers.AlInGaN For layers. samples For 1, sample 2, ands 3, 1, the 2, and peaks 3, the located peaks at located 33.8◦ on at the 33.8 left° on side the of left the side GaN of peaks the GaN belong peaks to InGaN,belong to which InGaN mean, which compositional mean compositional fluctuations fluctuations were formed were in formed samples. in samples. It is worth It is noting worth thatnoting in increasingthat in increasing the TMA the flow TMA rate flow from rate 1.15 tofrom 1.9 µ1.15mol/min, to 1.9 anotherμmol/min, peak another located pea atk 31.1 located◦ appeared at 31.1 in° samplesappeared 2 in and sample 3, correspondings 2 and 3, corresponding to InN. The appearance to InN. The of InNappear diffractionance of peaksInN diffraction in samples peaks 2 and in 3 indicatesamples that2 and phase 3 indicate separation that appears phase separation in the AlInGaN appears films in with the incrasingAlInGaN Alfilms content. with incrasing Al content.To further investigate the crystal quality of AlInGaN epilayer, the full width at half maximum (FWHM)To further of XRD investigate (0004) ! -2theθ scanscrystal of qual AlInGaNity of AlInGaN epilayers epilayer, versus TMAthe full flow width were at alsohalf maximum measured (listed(FWHM in) of Table XRD1). (0004) The FWHM ω-2θ scans of (0004) of AlInGaN!-2θ scan epilayers of AlInGaN versus TMA epilayers flow were were between also measured 195 to 252(listed arcsec, in Table corresponding 1). The FWHM withsamples of (0004) 1–4. ω-2θ When scan the of TMAAlInGaN flow epilayers rate was low,were the between lattice constant 195 to 252 of AlInGaNarcsec, corresponding epilayers was with closer sample to thats 1 of–4. GaN, When and the meanwhile TMA flow the rate composition was low, the of AlInGaN lattice constant epilayers of becameAlInGaN homogeneous epilayers was because closer to of that strain-free of GaN, growth;and meanwhile both of the these composition were expected of AlInGaN to narrow epilayers X-ray Crystals 2017, 7, 69 3 of 8 peaks. From Table2, the FWHM of AlInGaN diffraction peaks broadened as the Al content increased. Inhomogeneous strain, finite grain size, dislocations, and composition fluctuation are all responsible for broadening the diffraction peaks.
Load more

Recommended publications
  • Developing Aluminum Nitride Nanoparticles: Chemical Synthesis
    NanoPharma 2020 Der Pharmacia Sinica 2020 Vol.11 No.3 Developing Aluminum Nitride Nanoparticles: Chemical synthesis and Exploration of biocompatibility and anticancer activity against Cervical Cancer Cells Manjot Kaur 1, Kulwinder Singh 1, Paviter Singh 1, Amanpreet Kaur 1, 2, Ramovatar Meena 3, Gajendra 4 5 6 1 Pratap Singh , Hamed Barabadi , Muthupandian Saravanan *, Akshay Kumar 1Advanced Functional Material Lab., Department of Nanotechnology, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140 407, Punjab, India 2Department of Physics, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140 407, Punjab, India 3Nanotoxicology Laboratory, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110067, India 4School of Computational and Integrated Sciences, Jawaharlal Nehru University, New Delhi-110 067, India 5Department of Pharmaceutical Biotechnology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran 6Department of Medical Microbiology and Immunology, Division of Biomedical Sciences, School of Medicine, College of Health Sciences, Mekelle University, Mekelle, Ethiopia AlN nanoparticles were synthesized using a simple and sensors and implantable biomedical and effective solvothermal method. The X-ray diffraction results microelectromechanical devices. However, the development of revealed the cubic phase of AlN, and the field emission such materials is bound to one requirement, which is scanning electron microscopy analysis demonstrated the biocompatibility. The materials showing great chemical structural morphology of the synthesized materials. In addition, inertness, stability, and high compatibility with biological the cytotoxicity of the AlN nanoparticles was assessed against samples are considered optimal in this regard to be utilized in healthy (HEK-293, HUVEC, and MCF10A) and cancerous cell biomedical devices. The main benefit of the lower cytotoxicity line (HeLa).
    [Show full text]
  • Chemical Formula of Binary Ionic Compounds – Sheet 1 the Combining Power Or Valency of Silver Is Always 1
    Chemical Formula of Binary Ionic Compounds – Sheet 1 The combining power or valency of silver is always 1. All other transition metals are 2 unless otherwise indicated. No. Binary compound Formula No. Binary compound Formula 1 potassium fluoride 26 calcium sulfide 2 calcium chloride 27 lithium bromide 3 barium bromide 28 nickel sulfide 4 silver sulfide 29 zinc phosphide 5 aluminium iodide 30 barium iodide 6 potassium iodide 31 caesium chloride 7 lead(IV) oxide 32 copper bromide 8 zinc nitride 33 sodium nitride 9 silver iodide 34 silver chloride 10 barium fluoride 35 sodium hydride 11 lead(II) iodide 36 potassium nitride 12 silver fluoride 37 cobalt chloride 13 sodium sulfide 38 magnesium sulfide 14 sodium bromide 39 potassium chloride 15 calcium oxide 40 calcium bromide 16 zinc fluoride 41 iron(III) oxide 17 strontium phosphide 42 aluminium fluoride 18 barium sulfide 43 magnesium bromide 19 aluminium oxide 44 iron(III) chloride 20 aluminium chloride 45 barium nitride 21 aluminium sulfide 46 sodium fluoride 22 lead(II) oxide 47 lithium fluoride 23 barium chloride 48 lithium iodide 24 copper chloride 49 lithium hydride 25 barium phosphide 50 potassium oxide “Aluminum” and “cesium” are commonly used alternative spellings for "aluminium" and "caesium that are used in the US. May be freely copied for educational use. ©www.chemicalformula.org Chemical Formula of Binary Ionic Compounds – Sheet 2 The combining power or valency of silver is always 1. All other transition metals are 2 unless otherwise indicated. No. Binary compound Formula No.
    [Show full text]
  • First Principles Study of 2D Gallium Nitride and Aluminium Nitride in Square-Octagon Structure
    FIRST PRINCIPLES STUDY OF 2D GALLIUM NITRIDE AND ALUMINIUM NITRIDE IN SQUARE-OCTAGON STRUCTURE a thesis submitted to the graduate school of engineering and science of bilkent university in partial fulfillment of the requirements for the degree of master of science in physics By Emel G¨urb¨uz July 2017 FIRST PRINCIPLES STUDY OF 2D GALLIUM NITRIDE AND ALUMINIUM NITRIDE IN SQUARE-OCTAGON STRUCTURE By Emel G¨urb¨uz July 2017 We certify that we have read this thesis and that in our opinion it is fully adequate, in scope and in quality, as a thesis for the degree of Master of Science. Salim C¸ıracı(Advisor) Seymur Cahangirov Ay¸seC¸i˘gdemEr¸celebi Approved for the Graduate School of Engineering and Science: Ezhan Kara¸san Director of the Graduate School ii ABSTRACT FIRST PRINCIPLES STUDY OF 2D GALLIUM NITRIDE AND ALUMINIUM NITRIDE IN SQUARE-OCTAGON STRUCTURE Emel G¨urb¨uz M.S. in Physics Advisor: Salim C¸ıracı July 2017 This thesis, deals with the planar free-standing, single-layer, square-octagon (SO) structures of GaN and AlN. We investigated single-layer and multilayer so-GaN and so-AlN structures, their stability, electronic properties and functionalization; adatom and vacancies using first principles pseudopotential plane wave calcula- tions. We performed an extensive analysis of dynamical and thermal stability in terms of ab-initio finite temperature molecular dynamics and phonon calcu- lations together with the analysis of Raman and infrared active modes. These single layer square-octagon structures of GaN and AlN display directional me- chanical properties, and have fundamental indirect band gaps, which are smaller than their hexagonal counter parts.
    [Show full text]
  • Reactive Sputtering of Aluminum Nitride (002) Thin Films for Piezoelectric Applications: a Review
    Review Reactive Sputtering of Aluminum Nitride (002) Thin Films for Piezoelectric Applications: A Review Abid Iqbal and Faisal Mohd-Yasin * Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111, Australia; [email protected] * Correspondence: [email protected] Received: 24 April 2018; Accepted: 1 June 2018; Published: 2 June 2018 Abstract: We summarize the recipes and describe the role of sputtering parameters in producing highly c-axis Aluminum Nitride (AlN) films for piezoelectric applications. The information is collated from the analysis of around 80 journal articles that sputtered this film on variety of substrate materials, processes and equipment. This review will be a good starting point to catch up with the state-of-the-arts research on the reactive sputtering of AlN (002) thin film, as well as its evolving list of piezoelectric applications such as energy harvesters. Keywords: physical vapor deposition; sputtering; aluminum nitride; piezoelectric; energy harvester 1. Introduction Energy harvesting or energy scavenging is the process of extracting energy from the ambient sources in the environment. Energy harvester, instead of battery usage, is preferred for powering wireless sensors because the latter is limited by its limited life span. The ambient sources are broadly divided into four categories: Solar, thermal, wind, and mechanical vibration [1]. Researchers have investigated different methods to convert them into electrical energy via resonant and non-resonant devices [2]. A variety of transduction schemes have been proposed using solar, thermoelectric, electromagnetic, piezoelectric, capacitive etc. Among them, piezoelectric emerges as one of the most practical solutions. It does not require external power sources for polarization in comparison to the electrostatic transductions.
    [Show full text]
  • Oxidation Rates of Aluminium Nitride Thin Films: Effect of Composition of the Atmosphere
    J Mater Sci: Mater Electron DOI 10.1007/s10854-017-7243-5 Oxidation rates of aluminium nitride thin films: effect of composition of the atmosphere Ryszard Korbutowicz1 · Adrian Zakrzewski2 · Olga Rac‑Rumijowska1 · Andrzej Stafiniak1 · Andrej Vincze3 Received: 16 March 2017 / Accepted: 29 May 2017 © The Author(s) 2017. This article is an open access publication Abstract This paper presents an analysis of thermal oxi- 1 Introduction dation kinetics for Aluminium nitride (AlN) epitaxy layers using three methods: dry, wet and mixed. The structures The development of complex III-nitride semiconductor thus obtained were examined by means of scanning elec- technology has opened up new possibilities of using them tron microscope, energy-dispersive X-ray spectroscopy, in such devices as light emitters and detectors, diodes, spectroscopic ellipsometry and secondary ions mass spec- and microwave transistors [1]. New MOS- and MIS-based troscopy. On the basis of the investigation results, a model devices are used for the production of gases and other of layer structure after oxidation was proposed, the thick- chemical compounds detectors [2, 3]. Here surface passi- ness of the layers was assessed and the refractive indices for vation must be overcome to stabilise the properties of the particular layers were determined. The modelling results gas sensitive surface. The recent literature on this subject prove that AlN thermal oxidation in dry oxygen follows the includes a significant number of descriptions concerning logarithmic law, wet oxidation follows the parabolic law, the phenomena during the thermal dry and wet aluminium whereas mixed oxidation follows the linear law. oxidation. Among the main techniques for the production of passivation layers on the surface of III-nitride semiconduc- tor devices, the vacuum methods, often plasma-supported, are mentioned.
    [Show full text]
  • Photocurable Acrylate-Based Composites with Enhanced Thermal Conductivity Containing Boron and Silicon Nitrides
    eXPRESS Polymer Letters Vol.12, No.9 (2018) 790–807 Available online at www.expresspolymlett.com https://doi.org/10.3144/expresspolymlett.2018.68 Photocurable acrylate-based composites with enhanced thermal conductivity containing boron and silicon nitrides M. Sadej1, H. Gojzewski2,3, P. Gajewski1, G. J. Vancso3, E. Andrzejewska1* 1Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland 2Faculty of Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland 3Materials Science and Technology of Polymers, Faculty of Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, the Netherlands Received 7 February 2018; accepted in revised form 10 April 2018 Abstract. Boron nitride (BN) and silicon nitride (Si3N4) are very promising particulate fillers for production of photocurable composites dedicated to thermally conductive and electrically insulating protective coatings. Composites containing crosslinked methacrylate-based matrices filled with BN or Si3N4 (in amounts up to 5 wt%) were prepared in a fast in situ photocuring process with high conversion (>90%). The monomers were polyethylene glycol dimethacrylate and mono - methacrylate (50/50 by weight mixture). Investigations included determination of properties of the monomer/filler compo- sitions, photocuring kinetics and thermal, conductive and mechanical properties of the resulting composites. It was found that addition of the fillers improves polymerization kinetics and mechanical properties compared to the pure polymer matrix. Despite the very low loading level a substantial improvement in thermal conductivity was obtained: a 4-fold increase after addition of only 2 wt% of Si3N4 and 2.5-fold increase after addition of 0.5 wt% of BN.
    [Show full text]
  • Chemical Names and CAS Numbers Final
    Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number C3H8O 1‐propanol C4H7BrO2 2‐bromobutyric acid 80‐58‐0 GeH3COOH 2‐germaacetic acid C4H10 2‐methylpropane 75‐28‐5 C3H8O 2‐propanol 67‐63‐0 C6H10O3 4‐acetylbutyric acid 448671 C4H7BrO2 4‐bromobutyric acid 2623‐87‐2 CH3CHO acetaldehyde CH3CONH2 acetamide C8H9NO2 acetaminophen 103‐90‐2 − C2H3O2 acetate ion − CH3COO acetate ion C2H4O2 acetic acid 64‐19‐7 CH3COOH acetic acid (CH3)2CO acetone CH3COCl acetyl chloride C2H2 acetylene 74‐86‐2 HCCH acetylene C9H8O4 acetylsalicylic acid 50‐78‐2 H2C(CH)CN acrylonitrile C3H7NO2 Ala C3H7NO2 alanine 56‐41‐7 NaAlSi3O3 albite AlSb aluminium antimonide 25152‐52‐7 AlAs aluminium arsenide 22831‐42‐1 AlBO2 aluminium borate 61279‐70‐7 AlBO aluminium boron oxide 12041‐48‐4 AlBr3 aluminium bromide 7727‐15‐3 AlBr3•6H2O aluminium bromide hexahydrate 2149397 AlCl4Cs aluminium caesium tetrachloride 17992‐03‐9 AlCl3 aluminium chloride (anhydrous) 7446‐70‐0 AlCl3•6H2O aluminium chloride hexahydrate 7784‐13‐6 AlClO aluminium chloride oxide 13596‐11‐7 AlB2 aluminium diboride 12041‐50‐8 AlF2 aluminium difluoride 13569‐23‐8 AlF2O aluminium difluoride oxide 38344‐66‐0 AlB12 aluminium dodecaboride 12041‐54‐2 Al2F6 aluminium fluoride 17949‐86‐9 AlF3 aluminium fluoride 7784‐18‐1 Al(CHO2)3 aluminium formate 7360‐53‐4 1 of 75 Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number Al(OH)3 aluminium hydroxide 21645‐51‐2 Al2I6 aluminium iodide 18898‐35‐6 AlI3 aluminium iodide 7784‐23‐8 AlBr aluminium monobromide 22359‐97‐3 AlCl aluminium monochloride
    [Show full text]
  • Mechanism and Kinetics of Aluminum Nitride Powder Degradation in Moist Air
    J. Am. Ceram. Soc., 89 [3] 937–943 (2006) DOI: 10.1111/j.1551-2916.2005.00767.x r 2005 The American Ceramic Society Journal Mechanism and Kinetics of Aluminum Nitride Powder Degradation in Moist Air Jinwang Li,*,w Masaru Nakamura, Takashi Shirai, Koji Matsumaru, Chanel Ishizaki,z and Kozo Ishizaki* School of Mechanical Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan Aluminum nitride (AlN) powders manufactured via three major oxygen content in AlN powder.17 In contrast, degradation of commercial processes, namely, chemical vapor deposition from AlN powders in ambient atmospheres at room temperature has triethyl aluminum, carbothermal reduction and nitridation of been much less studied. Abid et al.18 reported that AlN did not alumina, and direct nitridation of aluminum, were exposed to readily react with atmospheric moisture at room temperature. moist air at room temperature to investigate the degradation On the other hand, Kameshima et al.19 found, using X-ray pho- mechanism and kinetics. In the degradation, the powders were toelectron spectrometry (XPS), that the surface of AlN powders initially hydrolyzed to amorphous aluminum oxyhydroxide, reacted slowly with atmospheric moisture during several years of which subsequently transformed into mixtures of crystallized storage in a capped container. aluminum trihydroxide (Al(OH)3) polymorphs, i.e., bayerite, A thorough understanding of the degradation mechanism nordstrandite, and gibbsite, forming agglomerates around the and kinetics for AlN powders under atmospheric conditions is unreacted AlN. The data were fitted by using the unreacted-core fundamental for appropriate powder processing. Unfortunately, model. Three stages were found in the degradation: the stage of research reports for this purpose are hitherto unavailable, in an induction period at the beginning, followed by a stage of fast contrast to numerous publications on AlN powder preparation, hydrolysis with the chemical reaction being rate controlling, and oxidation at elevated temperatures, sintering, etc.
    [Show full text]
  • Salt-Assisted SHS Synthesis of Aluminium Nitride Powders for Refractory Applications
    Journal of Materials Science and Chemical Engineering, 2014, 2, 26-31 Published Online October 2014 in SciRes. http://www.scirp.org/journal/msce http://dx.doi.org/10.4236/msce.2014.210004 Salt-Assisted SHS Synthesis of Aluminium Nitride Powders for Refractory Applications Alan Wilmański, Mirosław M. Bućko, Zbigniew Pędzich, Jacek Szczerba AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Krakow, Poland Email: [email protected] Received July 2014 Abstract Powders of aluminum nitride can be prepared by self-sustain high-temperature synthesis (SHS) between aluminum and nitrogen but its high exothermic effect causes melting and evaporation of aluminum and low efficiency of such reaction. A presence of inorganic salt in the starting powder mixture can decrease a heat evolved in the SHS reaction, hinders melting and coalescence of alu- minum, and facilitates penetration of nitrogen into interior of a powder bed. Mixtures of alumina powders with different grain sizes and different amounts of aluminum carbonate were subjected to the SHS reaction under 0.05, 0.1 or 1 MPa nitrogen. The powders were composed of aluminum nitride, unreacted aluminum, aluminum oxynitride and in some cases corundum and aluminum oxycarbonate. The finale effects are strongly dependent on the amount of the salt, a grain size of aluminum and a nitrogen pressure. Keywords Aluminum Nitride, Self-Sustain High-Temperature Synthesis, Salt Assisted Synthesis, Refractory Materials 1. Introduction Aluminum nitride, AlN, is a promising ceramic material for functional and structural applications due to its very high thermal conductivity, low electrical conductivity, high flexural strength of about 400 MPa and a hardness of about 15 GPa [1]-[3].
    [Show full text]
  • Piezoelectric Aluminium Nitride Thin Films by PECVD
    UNIVERSIDAD DE LA REPÚBLICA ORIENTAL DEL URUGUAY UNIVERSITÉ DE LIMOGES (FRANCE) CO-ADVISED THESIS For the degree DOCTOR EN INGENIERÍA QUÍMICA de la Facultad de Ingeniería de MONTEVIDEO DOCTEUR DE L’UNIVERSITÉ DE LIMOGES Spécialité: Matériaux Céramiques et Traitements de Surface Gustavo SÁNCHEZ MATHON February the 12 th 2009, Montevideo, Uruguay PIEZOELECTRIC ALUMINUM NITRIDE THIN FILMS BY PECVD Advisors: Aldo BOLOGNA ALLES / Pascal TRISTANT, Christelle DUBLANCHE-TIXIER Jury : President : Prof. Jean Claude LABBE SPCTS, Limoges (France) Revisors: Prof. Miriam CASTRO UNMDP, Mar del Plata (Argentina) Prof. Abdou DJOUADI IMN, Nantes (France) Members: Prof. Ismael PIEDRA-CUEVA FING, Montevideo (Uruguay) Prof. Enrique DALCHIELE FING, Montevideo (Uruguay) Dr. Christelle DUBLANCHE-TIXIER SPCTS, Limoges (France) Prof. Pascal TRISTANT SPCTS, Limoges (France) Prof. Aldo BOLOGNA ALLES FING, Montevideo (Uruguay) Acknowledgments I want to express my sincere gratitude to my thesis advisors, Dr. Aldo Bologna Alles, Dr. Pascal Tristant and Dr. Christelle Dublanche-Tixier for their friendship and guidance throughout the course of this work. I also gratefully acknowledge Dr. Jean Claude Labbe, Dr. Ismael Piedra-Cueva, Dr. Abdou Djouadi, Dr. Miriam Castro, and Dr. Enrique Dalchiele for serving on my committee. I would also like to thank to several members of the SPCTS laboratory at Limoges for their support: Daniel Tetard, Thérèse Merle, Valérie Coudert, Phillippe Thomas, Alexandre Boulle, René Guinebretiere, Bernard Soulestin, Fabrice Rossignol, Daniel Merle and Cédric Jaoul. I would like to give a special acknowledge in this sense to Hervé Hidalgo. I want to acknowledge to Jaume Esteve and Joseph Montserrat from the Instituto de Microelectrónica de Barcelona for their assistance in the cleanroom fabrication of SAW devices, as well as to Aurelian Crunteanu from X-LIM (Limoges) for his assistance in the cleanroom fabrication of BAW devices as well in the device characterizations.
    [Show full text]
  • Filament-Activated Chemical Vapour Deposition of Nitride Thin Films
    ADVANCED MATERIALS FOR OPTICS AND ELECTRONICS, VOL 6,135-146 (1996) Review Paper Filament-activated Chemical Vapour Deposition of Nitride Thin Films Sadanand V. Deshpande,* Jeffrey L. Dupuiet and Erdogan Gulari* Department of Chemical Engineering and Center for Display Technology and Manufacturing, The University of Michigan, Ann Arbor, MI 48109, U.S.A. We have applied the novel method of hot filament-activated chemical vapour deposition (HFCVD) for low-temperature deposition of a variety of nitride thin films. In this paper the results from our recent work on aluminium, silicon and titanium nitride have been reviewed. In the HFCVD method a hot tungsten filament (1500-1850°C) was utilised to decompose ammonia in order to deposit nitride films at low substrate temperatures and high rates. The substrate temperatures ranged from 245 to 600°C. The film properties were characterised by a number of analytical and optical methods. The effect of various deposition conditions on film properties was studied. All the films obtained were of high chemical purity and had very low cr no detectable tungsten contamination from the filament metal. KEYWORDS hot filament chemical vapour deposition; CVD; high-rate deposition; ammonia: silicon nitride: aluminium nitride: titanium nitride INTRODUCTION design and operating regimes, films with varied properties can be deposited with little or no COP- tamination from reactions at the reactor walls as is Hot filament-activated chemical vapour deposition found in other techniques such as plasma-assisted (HFCVD) is a simple and a relatively inexpensive chemical vapour deposition. method that has been used to deposit a variety of HFCVD has been extensively used for over a materials.
    [Show full text]
  • Bulk Aluminium Nitride Platform for Gallium Nitride High Voltage And
    82 Technology focus: Nitride electronics Bulk aluminium nitride platform for gallium nitride high voltage and power Researchers claim first measurements on quantum well field-effect transistors achieve record high drain current of 2A/mm. he USA’s University of Notre Dame and Cornell University have claimed the first Tmeasurements on aluminium nitride/ gal- lium nitride (AlN/GaN/AlN) quantum well (QW) field-effect transistors (FETs) on bulk AlN sub- strates with re-grown ohmic contacts [Meng Qi et al, Appl. Phys. Lett., vol110, p063501, 2017]. A device with 65nm gate length achieved a record-high drain current of 2A/mm, it is claimed. The researchers see potential for future high- voltage and high-power microwave electronics. The use of AlN increases the bandgap to 6.2eV, while a large conduction band offset increases the electron confinement in GaN QWs. The GaN/AlN charge polarization contrast should also increase carrier densities and drive currents. Another attractive feature of AlN is a high ther- mal conductivity of 340W/m-K, close to that of silicon carbide substrates (370W/m-K), which are often used for state-of-the-art AlGaN/GaN devices. High thermal conductivity relieves heat dissipation in high-power operation. The AlN/GaN/AlN quantum well structures (Figure 1) were grown by radio frequency plasma molecular beam epitaxy (MBE) on semi- insulating aluminium-polar bulk AlN substrates. The wafers were 400µm thick. The structure also included a 1.5nm GaN cap to prevent oxi- dation of the 6nm AlN top barrier. The conductivity of the two-dimensional elec- tron gas (2DEG) that forms near the AlN/GaN QW interface through charge polarization effects Figure 1.
    [Show full text]