GaN Layers Grown by HVPE on P-type 6H-SiC Substrates
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Internet Journal o f
Nitride S emiconductor Research
Volume 1, Article 45
GaN Layers Grown by HVPE on P-type 6H-SiC Substrates A.E. Nikolaev, Yu.V. Melnik, M.N. Blashenkov, N.I. Kuznetsov, I.P. Nikitina, A.S. Zubrilov, D.V. Tsvetkov Cree Research EED and Ioffe Physical-Technical Institute V. I. Nikolaev, V.A. Dmitriev, V.A. Soloviev Ioffe Physical-Technical Institute This article was received on June 2, 1996 and accepted on December 19, 1996.
Abstract Gallium nitride films were successfully grown by HVPE technique on p-type 6H-SiC substrate. The layers exhibit high crystal quality as was determined by X-ray diffraction. Photoluminescence (PL) of these films was measured. The PL spectra were dominated by band edge emission. Concentration Nd-Na in undoped epitaxial layers ranged from 2x1017 to 1x101 9 cm-3. Mesa-structures formed by reactive ion etching showed good rectifying current-voltage characteristics for GaN/SiC pn heterojunctions.
1. Introduction 1.1. HVPE Advantages The HVPE method is a promising technique for deposition of thick GaN single crystal layers. The main advantages of this method are high growth rate and low cost. Recent progress in HVPE growth shows that high quality GaN layers can be obtained [1] [2] [3]. The crystalline, electrical and optical properties of these films are comparable with the best characteristics reported in the literature for GaN produced by MOCVD [4] [5] and MBE [6] [7]. Besides, HVPE allows one to grow high quality GaN layers on SiC substrates without any buffer layer [1]. This feature is important for producing electronic devices with vertical geometry.
1.2. GaN/SiC Heterodevices The direct deposition of GaN on SiC also provides one the opportunity to create devices based on GaN/SiC heterojunctions (e.g. heterojunction bipolar transistor) [8] [9]. Recently p-GaN on n-SiC has been successful grown by MBE and junction characteristics have been achieved. [10].
1.3. Alternative to Ohmic Contact to p-GaN? One of the obstacles in GaN device fabrication is the absence of a suitable ohmic contact to p-GaN. To overcome this problem, the inverse GaN device structure i.e. pSiC (substrate)/pGaN/.../nGaN may be used. The best ohmic contact to p-GaN [11] has a resistivity about 3 orders of magnitude higher than that for n-GaN [11] [12] and about 2 orders of magnitude higher than that for p-SiC [13]. A large area p-contact to SiC will contribute negligibly to the overall device series resistance. However to the best of our knowledge there are no reports on growth GaN on p-type SiC substrates. In this paper we report on properties of n-GaN layers grown by HVPE directly on p-type SiC substrates. Preliminary result on n-GaN/p-SiC heterojunction are presented. Downloaded from https://www.cambridge.org/core. IP address: 194.156.124.94, on 22 Oct 2020 at 07:12:07, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/S1092578300002179
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2. Experiments 2.1. GaN Epitaxial Growth GaN n-type layers were grown by HVPE on p-ty
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