Semiconductor Materials for Optoelectronics and LTMBE Materials, PROCEEDINGS OF SYMPOSIUM A ON SEMICONDUCTOR MATERIALS FOR OPTOELECTRONIC DEVICES, OEICS AND PHOTONICS AND SYMPOSIUM B ON LOW TEMPERATURE MOLECULAR BEAM EPITAXIAL III–V MATERIALS: PHYSICS A PDF
Preview Semiconductor Materials for Optoelectronics and LTMBE Materials, PROCEEDINGS OF SYMPOSIUM A ON SEMICONDUCTOR MATERIALS FOR OPTOELECTRONIC DEVICES, OEICS AND PHOTONICS AND SYMPOSIUM B ON LOW TEMPERATURE MOLECULAR BEAM EPITAXIAL III–V MATERIALS: PHYSICS A
EUROPEAN MATERIALS RESEARCH SOCIETY SYMPOSIA PROCEEDINGS Volume 1: Ceramic Materials Research (ed. R.J. Brook) Volume 2: Photon, Beam and Plasma Assisted Processing (eds. I.W. Boyd and E.F. Krimmel) Volume 3 Deep Implants (eds. G.G. Bentini, A. Golanski and S. Kalbitzer) Volume 4 Metastable Alloys: Preparation and Properties (eds. K. Samwer, M. von Allmen, J. B0ttinger and B. Stritzker) Volume 5 Superconducting and Low-Temperature Particle Detectors (eds. G. Waysand and G. Chardin) Volumes 6A, 6B: High T Superconductors (eds. P.F. Bongers, C. Schlenker and B. Stritzker) c Volume 7: Solid State Ionics (eds. M. Balkanski and C. Julien) Volume 8: Rare-Earth Permanent Magnets (ed. I.R. Harris) Volume 9: Defects in Silicon (eds. C.A.J. Ammerlaan, A. Chantre and P. Wagner) Volume 10A, 10B: Silicon Molecular Beam Epitaxy (eds. E. Kasper and E.H.C. Parker) Volume 11: Acoustic, Thermal Wave and Optical Characterization of Materials (eds. G.M. Crean, M. Locatelli and J. McGilp) Volume 12: Beam Processing and Laser Chemistry (eds. I.W. Boyd and E. Rimini) Volume 13: Interfaces in Biomaterials Sciences (eds. D. Muster and G. Hastings) Volume 14A, 14B: High T Superconductor Materials (eds. H.-U. Habermeier, E. Kaldis and J. Schoenes) c Volume 15: Metal Matrix Composites (eds. G. Chadwick and L. Froyen) Volume 16: Magnetic Thin Films, Multilayers and Superlattices (eds. A. Fert, G. Güntherodt, B. Heinrich, E.E. Marinero and M. Maurer) Volume 17: Metallurgical Coatings and Materials Surface Modifications (eds. H. Hintermann and J. Spitz) Volume 18: Surface Processing and Laser Assisted Chemistry (eds. I.W. Boyd, E. Fogarassy and M. Stuke) Volume 19: Materials for Optoelectronic Devices, OEICs and Photonics (eds. H. Schlötterer, M. Quillec, P.D. Greene and M. Bertolotti) Volume 20: SiC, Natural and Synthetic Diamond and Related Materials (eds. A.A. Gippius, R. Helbig and J.P.F. Sellschop) Volume 21: Analytical Techniques for the Characterization of Compound Semiconductors (eds. G. Bastard and H. Oppolzer) Volume 22: Micronic Integrated Sensors (ed. J.L. Robert) Volume 23: High Energy and High Dose Ion Implantation (eds. S.U. Campisano, J. Gyulai, P.L.F. Hemment and J.A. Kilner) Volume 24: Laser Surface Processing and Characterization (ed. I.W. Boyd) Volume 25: Nuclear Methods in Semiconductor Physics (eds. G. Langouche, J.C. Soares and J.P. Stoquert) Volume 26: Clays and Hydrosilicate Gels in Nuclear Fields (ed. A. Meunier) Volume 27: Chemistry of Cements for Nuclear Applications (eds. P. Barret and F.P. Glasser) Volume 28: Nuclear Materials for Fission Reactors (eds. Hj. Matzke and G. Schumacher) Volume 29: Modifications Induced by Irradiation in Glasses (ed. P. Mazzoldi) Volume 30: Poly conjugated Materials (ed. G. Zerbi) Volume 31: SiGe Based Technologies (eds. E. Kaspar, Y. Shiraki and T.P. Pearsall) Volume 32: Materials Surface Processing (eds. M. Stuke, E.E. Marinero and I. Nishiyama) Volume 33: Chemistry for Electronic Materials (eds. Y. Pauleau, G. Wahl, K.F. Jensen and T. Hirai) Volume 34: Semiconductor Materials Analysis and Fabrication Process Control (eds. G. Crean, R. Stuck and J. Woollam) Volume 35: Synthetic Materials for Non-Linear Optics and Electronics (eds. C. Taliani, Z.V. Vardeny and Y Maruyama) Volume 36: CdTe and Related Cd Rich Alloys (eds. R. Triboulet, WR. Wilcox and O. Oda) Volume 37: Single Chamber Processing (eds. Y.I. Nissim and A. Katz) Volume 38: High T Superconductors (eds. J. Dumas, H.W. Neumüller, H.F. Braun, V.P. Seminozhenko and Yu.D. Tretyakov) c Volume 39: Materials under Extreme Conditions and Nanophase Materials (eds. G. Kostorz, I. Gorynin, V Trevilov, H.-D. Kunze, B. Skorokhod and V Troitsky) Volume 40: Semiconductor Materials for Optoelectronics and LTMBE Materials (eds. J.P. Hirtz, C. Whitehouse, H.P. Meier, HJ. von Bardeleben and M.O. Manasreh) SEMICONDUCTOR MATERIALS FOR OPTOELECTRONICS AND LTMBE MATERIALS PROCEEDINGS OF SYMPOSIUM A ON SEMICONDUCTOR MATERIALS FOR OPTOELECTRONIC DEVICES, OEICs AND PHOTONICS AND SYMPOSIUM B ON LOW TEMPERATURE MOLECULAR BEAM EPITAXIAL III-V MATERIALS: PHYSICS AND APPLICATIONS OF THE 1993 E-MRS SPRING CONFERENCE STRASBOURG, FRANCE, MAY 4-7,1993 Edited by J.P. HIRTZ Thomson-CSF, Orsay, France C. WHITEHOUSE Defense Research Agency, Great Mähern, U.K. H.P. MEIER Rüschlikon, Switzerland HJ. VON BARDELEBEN Universites Paris 6 &7, Paris, France M.O. MANASREH Wright Laboratory,Dayton, OH, U.S.A. m ES 1993 NORTH-HOLLAND AMSTERDAM-LONDON-NEW YORK-TOKYO © 1993 ELSEVIER SEQUIOIA S.A. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the copyright owner, Elsevier Sequioia S.A., P.O. Box 564, 1001 Lau sanne, Switzerland. Special regulations for readers in the U.S.A. - This publication has been registered with the Copy right Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be referred to the copyright owner, Elsevier Sequioia S.A., unless otherwise specified. No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Printed on acid-free paper ISBN: 0444 81769 7 Published by: North-Holland Elsevier Science Publishers B.V. Sara Burgerhartstraat 25 P.O. Box 211 1000 AE Amsterdam The Netherlands Reprinted from: MATERIALS SCIENCE AND ENGINEERING B21 (2,3) and B22 (1) The manuscripts for the Proceedings were received by the Publisher: early July 1993 Printed in The Netherlands Preface The symposium "Materials for Optoelectronic Devices, OEICs and Photonics", held in Strasbourg, May 4-7, 1993, was part of the European Materials Research Society (E-MRS) Spring Meeting; several other symposia were devoted to the related topics of integrated processing for micro and optoelectronics, light emission in silicon and LTMBE III-V materials. This 3-day symposium was designed to provide a link between specialists coming from university or industry, and working in different fields of semiconductor optoelectronics. The main topics covered during this symposium were: • Epitaxial growth of III-V, II-VI, IV-VI, Si-based structures • Selective-area, localized and non-planar epitaxy, shadow-mask epitaxy • Superlattices, quantum size structures • Strained layer structures • Bulk and new optoelectronic materials • Optoelectronics on silicon • Polymers for optoelectronics • Optoelectronic devices The chairmen of this symposium would like to acknowledge Dr. Schlölleter from SIEMENS and Professor Dr. G. Tränkle from the Technical University of Munich for their most valuable help in the organization of this meeting. They are also grateful to the local E-MRS organizers and to the referees who helped to prepare these proceedings. Finally, we would like to thank the following for their financial support: the E-MRS and its President Dr. Glasgow, the E-MRS Network GaAs, particularly Professor D. G. Weimann, and finally Dr. G. Witt from the US Air Force Office for Scientific Research. J. P. Hirtz H. Meier C. Whitehouse Guest Editors Xll Organizers and Sponsors Symposium Chairmen: J. P. Hirtz H. Meier THOMSON CSF/LCR IBM Zurich Research Laboratory Domaine de Corbeville Säumerstrasse 4 91404 Orsay Cedex 8803 Rüschlikon France Switzerland C. Whitehouse 3 Christchurch Road Malvern Worcestershire WR14 3BH UK Scientific Committee G. Tränkle (Germany) H. Schlotterer (Germany J. von Bardeleben (France) Sponsors This Conference was held under the auspices of: The Council of Europe The Commission of European Communities It is our pleasure to acknowledge with gratitude the financial assistance provided by Banque Populaire (France) Brasserie Adelshoffen (France) Centre de Recherches Nucleaires (France) Centre National de la Recherche Scientifique (France) Elsevier Science Publishers B.V. (Netherlands) La Maison du Cafe - Ergersheim (France) Office du Tourisme de la Ville de Strasbourg (France) The Commission of European Communities The Council of Europe The European Parliament Preface Symposium B of the E-MRS Spring Meeting, 1993 was the first European meeting on the subject of III-V epitaxial layers grown by low temperature molecu lar beam epitaxy (LTMBE). This subject has undergone rapid development in the last three years, particularly in the USA where different MRS symposia had already been devoted to this area. The point of interest in this growth technique is that it allows the growth of layers with extremely high defect concentrations but still of excellent crystallinity. The electrical and optical properties are modified—in particular high resistive material can be elaborated—giving rise to many applica tions. Although up to now most of the results have been obtained for LTMBE GaAs, this technique can also be applied to all other 3-5 compounds and alloys. At the E-MRS meeting papers were presented on the following topics: • Growth and characterization of undoped high resistive LTMBE III-V epitaxial layers: GaAs, GalnAs, AlInAs, InP, GaP. • Application of LTMBE III-V layers in microelectronics: MESFETS, HEMTS, MISFETS. • Optoelectronic applications of LTMBE GaAs. A series of six invited papers, giving an overview of the current activity in this field, was presented: "LTMBE GaAs: present status and perspectives" by G. L. Witt of AFOSR/NE, Boiling AFB (USA); "Point defects in III-V materials grown by molecular beam epitaxy at low temperature" by P. Hautojärvi, J. Mäkinen, S. Palko and K. Saarinen of Helsinki University of Technology, Espoo (Finland), C. Corbel and L. Liszkay of Centre d'Etudes Nucleaires de Saclay, Gif-sur-Yvette (France); "GaAs, AlGaAs, and InGaAs epilayers containing As clusters: semimetal/semiconductor composites" by M. R. Melloch of Purdue University, Indiana (USA), J. M. Woodall of IBM T. J. Watson Research Centre, New York (USA), N. Otsuka, K. Mahalingam, C. L. Chang and D. D. Nolte of Purdue University, Indiana (USA); "Extended defects and precipitates in LT-GaAs, LT- InAlAs and LT-InP" by A. Claverie of CEMES/LOE, Toulouse (France) and Z. Liliental-Weber, Lawrence Berkeley Laboratory, Berkeley, CA (USA); "Optoelectronic applications of LTMBE III-V materials" by J. F. Whitaker of University of Michigan, Ann Arbor, MI (USA); "Applications of GaAs grown at a low temperature by molecular beam epitaxy" by U. K. Mishra of University of California, Santa Barbara, CA (USA). We would like to thank the US Air Force Office of Scientific Research (EOARD) for financial support. H. J. von Bardeleben J. P. Hirtz M. O. Manasreh Guest Editors 11 Organizers and Sponsors Symposium Chairmen: H. J. von Bardeleben M. O. Manasreh Groupe de Physique des Solides Wright Laboratory, WL/ELRA Universites Paris 6 & 7 Wright Patterson AFB 2 Place Jussieu Dayton, OH 45433-6543 75251 Paris Cedex 05 USA France J. P. Hirtz Thomson-CSF Domain de Corbeville 91404 Orsay Cedex France Sponsors This Conference was held under the auspices of: The Council of Europe The Commission of European Communities It is our pleasure to acknowledge with gratitude the financial assistance provided by Banque Populaire (France) Brasserie Adelshoffen (France) Centre de Recherches Nucleaires (France) Centre National de la Recherche Scientifique (France) Elsevier Science Publishers B.V. (Netherlands) La Maison du Cafe - Ergersheim (France) Office du Tourisme de la Ville de Strasbourg (France) The Commission of European Communities The Council of Europe The European Parliament Materials Science and Engineering, B21 (1993)107-119 107 Stoichiometry of III-V compounds Jun-ichi Nishizawa Tohoku University, Katahira Aoba-ku 2-1-1, Sendai (Japan) Abstract The effects of stoichiometry on various features of III-V compounds are investigated. Application of the optimum vapour pressure of group V elements is shown to minimize the deviation from stoichiometric composition. The temperature dependence of the optimum vapour pressure is also obtained from both annealing and liquid phase epitaxial growth experiments. Vapour pressure technology is successfully applied to bulk crystal growth. In view of the defect formation mechanism, the role of the stable interstitial As atoms (I ) in GaAs is emphasized. The mechanism of stoichiometry As control is discussed on the basis of the equality of chemical potentials and the change in saturating solubility in the liquidus phase as a function of the vapour pressure. 1. Introduction well as to antisite defects, because the so-called EL2 level relates to the excess As composition of GaAs The most important factor to be controlled in com crystals. Indeed, recent results of quasi-forbidden pound semiconductor crystals is the deviation from X-ray reflection seem to show the existence of inter stoichiometric composition. Since the investigation of stitial As atoms [9]. iron pyrite in 1951 [1], annealing experiments on Vapour pressure control technology has also been various III-V compound semiconductor crystals have applied in the field of bulk crystal growth [10]. It has been carried out under controlled vapour pressure of been shown that high purity GaAs crystals can be the group V element [2, 3]. It is shown that nearly obtained with controlled composition and that very perfect crystals with stoichiometric composition are low dislocation densities (as low as 2000 cm"2) can be produced under a specific vapour pressure and that the achieved even in Czochralski (CZ) grown semi-insu temperature dependence of the optimum vapour pres lating GaAs crystals of diameter 4 in. This enables the sure is also obtained. fabrication of superbright light-emitting diodes (LEDs) In view of the defect formation mechanism, the role [11], including pure green LEDs without nitrogen of interstitial As atoms (I ) in GaAs crystals was doping in GaP [12]. Vapour pressure control during As emphasized when GaAs was annealed under high As crystal growth, which enables control of the stoichio vapour pressure [4]. The As vapour pressure depen metric composition, is applied extensively not only to dence on the specific weight and the intensity of III-V compounds, e.g. InP, but also to II-VI com anomalous X-ray transmission implies the existence of pounds, e.g. ZnSe [13]. It should also be important in interstitial As atoms [5]. Our Rutherford-backscatter- the research field of superconducting ceramics. ing spectroscopy (RBS) experiments have also revealed In this review the annealing effects of GaAs under interstitial As atoms in As+-implanted GaAs and arsenic vapour pressure are shown. The electrical, enabled us to determine the stable interstitial sites in optical and crystallographic properties are improved the deformed lattice [61. The RBS results on the stable under a specific arsenic vapour pressure denoted P . opt interstitial sites are in good accordance with those of In view of the stoichiometry-dependent deep levels, anomalous X-ray transmission measurements [5]. PHCAP results for annealed GaAs crystals are shown. Photocapacitance measurements under constant- The diffusion phenomenon in GaAs is closely related capacitance conditions have shown stoichiometry- to the stoichiometric composition. It is shown that the dependent deep levels and clarified the As vapour amphoteric behaviour of group IV elements (Sn [14] pressure dependences of the deep level densities [7]. and Si [15]) in GaAs is controlled by the application of The formation energy of the defects was also obtained vapour pressure during liquid phase epitaxial (LPE) as 1.16 eV [8], This value relates more closely to inter growth. Results of LPE growth of GaAs by means of stitial atoms than to vacancies. Recently much attention the temperature difference method under controlled has been devoted to interstitial As atoms in GaAs as vapour pressure (TDM-CVP) are also shown. This can 0921-5107/93/86.00 © 1993 - Elsevier Sequoia. All rights reserved 108 J. Nishizawa / StoichiometryofIII-Vcompounds be extended to the results of melt growth by Suzuki and Two temperature zone furnace Akai [16] and Parsey et al. [17]. Similar results are also obtained for LPE growth of GaP under controlled phosphorus vapour pressure. Vapour pressure control technology can also be extended to GaAs bulk crystal melt growth. Crystal quality is shown as a function of the arsenic vapour pressure. In view of the non-stoi- chiometric defect formation mechanisms, PHCAP and RBS results are shown in combination with results of (PAS'V <PAsÄ JAJs crystal specific weight and anomalous X-ray transmis Fig. 1. Schematic drawing of the equipment for annealing under sion intensity measurements. The important role of As vapour pressure. interstitial As atoms in GaAs is emphasized. In view of the surface stoichiometry and precise control of stoi- chiometric composition during vapour phase epitaxial 10 growth, experimental results of molecular layer epitaxy P(As) = 7.2 Torr P(As) = 63 Torr P(As) = yx1 ί TorJ (MLE) of GaAs are described. The importance of P(As) = 7.9x11 Torr P(As) = 2.8x13 Tori surface stoichiometry is also emphasized in the research field of surface science. Finally, theoretical 18 consideration is also shown by taking into account the Na 10 deviation from stoichiometric composition. [cm3] 2. Annealing effects on GaAs crystals under As 17 vapour pressure 10 Annealing experiments were performed at · 900-1100 °C for 67 h under various As vapour pres 10 17 10 18 10 19 sures. The samples used were (lOO)-oriented hori Initial Electron Density [cm ] zontal Bridgman (HB) grown GaAs with various Fig. 2. Change in acceptor density induced by annealing as a impurity densities. The defect density introduced by function of the initial electron density in Te-doped GaAs. annealing reaches its saturation value after 67 h of annealing. Figure 1 shows a schematic drawing of the equipment for annealing under As vapour pressure. The As vapour pressure applied on the GaAs crystals was obtained as 11/2 1 GaAs *GaAs ~~ P\ (1) Na [cm3] 10 where F is the equilibrium As vapour pressure deter As mined from the temperature of arsenic metal (T ) and As ^GaAs is the temperature of the GaAs crystals. The equilibrium As vapour pressure was obtained by Honig [18]. After annealing, the samples were cooled rapidly by plunging them into water in order to avoid any effect of slow cooling. X-ray and etching inspection 10° 101 10" 10 10 Arsenic Vapor Pressure [Torr] revealed no slip lines even after rapid cooling. Figure 2 shows the change in acceptor density Fig. 3. Arsenic vapour pressure dependence of the acceptor density in Te-doped GaAs. Annealing was performed at induced by annealing as a function of the initial 900-1100 °C for 67 h. electron density in Te-doped GaAs after annealing. The acceptor density is almost proportional to the initial electron density. This shows that acceptor-type The lattice constant was measured using double-crystal defects relate to both the deviation from stoichiometric X-ray diffraction with the (004) symmetrical configura composition and the dopant impurity Te. Figures 3 and tion. The various symbols in the figures denote data 4 show the As vapour pressure dependences of the obtained from crystals with different electron densities. acceptor density and the lattice constant respectively. The acceptor density shows a minimum under a J.Nishizawa / Stoichiometry of HI-V compounds 109 specific As vapour pressure (P ,o t)· Under almost the 5.6532 As P same As vapour pressure, the lattice constant also 900 -c 1050.c 1100-c shows its minimum value. It seems that nearly perfect 5.6531 crystals with stoichiometric composition could be 5.6530 obtained under P . Almost the same results were As>opt obtained for Zn-doped GaAs crystals. Therefore Lattice constant 5.6529 ^As,ot is independent of the impurity concentration P [A] and dopant species. Almost the same results were also 5.6528 obtained in annealing experiments on GaP and opti mum phosphorus pressure (^P?opt) was shown to 5.6527 GaAs:Te improve the crystal quality. However, in the case of GaP, the lattice constant shows its maximum value 5.6526 i 11 nid i imirf i iium I IIIIMJ I I III! ,,J -* 10' 10 10 10 10 10 10-^4 io5 under a specific phosphorus vapour pressure. Arsenic Vapor Pressure [Torr] Consequently, optimum vapour pressures were Fig. 4. Arsenic vapour pressure dependence of the lattice obtained as a function of annealing temperature for constant of Te-doped GaAs. The lattice constant was measured GaAs and GaP respectively as by double-crystal X-ray diffractometry. 1.05 eV PGaAs,oPt = 2.6xl06expI-■ (2) 2E+16 70K FGaP,opt = 4.67xl06exp - (3) 2E+16 (a) / I In order to investigate the deep levels in annealed GaAs crystals, PHCAP measurements [19] were Nt [cm*] 1E+16 carried out under constant-capacitance conditions [20]. The PHCAP method enables precise determination of *"U/<b> the level density and activation energy, because ioniza- 5E+15 tion by monochromatic light irradiation at a fixed, very low temperature was used. In contrast with the conven tional PHCAP method, the depletion layer thickness is _ <c> _ kept constant regardless of the change in ion density 0E+00 I '" ■ ■ i '■""IT" **""""" , i 0.5 1 1.5 due to light irradiation. PHOTON ENERGY [eV] In order to obtain accurate values of level density Fig. 5. Ion density PHCAP spectra of intentionally undoped and level position, fully neutralized deep levels should GaAs (rc = 4xl016 cm-3) grown by the HB method before be ionized at each wavelength. One method of achiev annealing: (a) and (b) show the maximum (Nmax) and asymptotic (N ) ion densities respectively; (c) represents the ion density ing this is to apply forward bias injection in the dark asym (Ndark) in the dark after forward bias injection. before each photoexcitation. In n-type GaAs bulk crystals the so-called photoquenching phenomenon [21] is observed in a specific wavelength region of about 1.0-1.5 eV below about 110 K. Therefore both 10x10 the maximum and asymptotic saturation ion densities were obtained at each wavelength. 8x10 Figure 5 shows the PHCAP spectra of intentionally undoped GaAs (« = 4x 1016 cm-3) grown by the HB Nt 6x10 method before annealing [22]. Curves (a) and (b) show [cm3 ] the maximum (N ) and asymptotic (N ) ion den max asym 4x10 sities respectively. Curve (c) represents the ion density (7V ) in the dark after forward bias injection. N dark daTk corresponds to the ion density in the dark before 2x10 photoexcitation. The almost constant value of N daTk verifies the photoexcitation of fully neutralized deep 1.0 1.5 levels at each wavelength. Figure 6 shows the PHCAP Photon Energy [eV] spectrum obtained by subtracting Nasym from Nmax. Fig. 6. Deionized level density PHCAP spectrum obtained from This is the deionized level density spectrum. the subtraction of N from N . asym max
The list of books you might like
