Preparation and optimization of freestanding GaN using low-temperature GaN layer

Abstract

In this work, a method to acquire freestanding GaN by using low temperature (LT)-GaN layer was put forward. To obtain porous structure and increase the crystallinity, LT-GaN layers were annealed at high temperature. The morphology of LT-GaN layers with different thickness and annealing temperature before and after annealing was analyzed. Comparison of GaN films using different LT-GaN layers was made to acquire optimal LT-GaN process. According to HRXRD and Raman results, GaN grown on 800 nm LT-GaN layer which was annealed at 1090 °C has good crystal quality and small stress. The GaN film was successfully separated from the substrate after cooling down. The self-separation mechanism of this method was discussed. Cross-sectional EBSD mapping measurements were carried out to investigate the effect of LT-buffer layer on improvement of crystal quality and stress relief. The optical property of the obtained freestanding GaN film was also determined by PL measurement.

Keywords

GaN / self-separation / low-temperature / annealing

References

[1] Darakchieva V, Paskova T, Paskov P P, . Residual strain in HVPE GaN free-standing and re-grown homoepitaxial layers. Physica Status Solidi A: Applied Research, 2003, 195(3): 516–522

[2] Richter E, Gründer M, Schineller B, . GaN boules grown by high rate HVPE. Physica Status Solidi C: Current Topics in Solid State Physics, 2011, 8(5): 1450–1454

[3] Luo W, Wang X, Xiao H, . Growth and fabrication of AlGaN/GaN HEMT based on Si (111) substrates by MOCVD. Microelectronics Journal, 2008, 39(9): 1108–1111

[4] Cui Y, Li L. Evolution of spirals during molecular beam epitaxy of GaN on 6H-SiC (0001). Physical Review B: Condensed Matter, 2002, 66(15): 155330

[5] Cho S I, Chang K, Kwon M S. Strain analysis of a GaN epilayer grown on a c-plane sapphire substrate with different growth times. Journal of Materials Science, 2007, 42(10): 3569–3572

[6] Qian W, Skowronski M, De Graef M, . Microstructural characterization of α-GaN films grown on sapphire by organometallic vapor phase epitaxy. Applied Physics Letters, 1995, 66(10): 1252–1254

[7] Kim H M, Oh J E, Kang T W. Preparation of large area free-standing GaN substrates by HVPE using mechanical polishing liftoff method. Materials Letters, 2001, 47(4‒5): 276–280

[8] Kelly M K, Vaudo R P, Phanse V M, . Large free-standing GaN substrates by hydride vapor phase epitaxy and laser-induced liftoff. Japanese Journal of Applied Physics, 1999, 38(Part 2, No. 3A): L217–L219

[9] Oshima Y, Eri T, Shibata M, . Fabrication of freestanding GaN wafers by hydride vapor-phase epitaxy with void-assisted separation. Physica Status Solidi, 2002, 194(2): 554–558

[10] Oshima Y, Eri T, Shibata M, . Preparation of freestanding GaN wafers by hydride vapor phase epitaxy with void-assisted separation. Japanese Journal of Applied Physics, 2003, 42(Part 2, No.1A/B): L1–L3

[11] Chao C L, Chiu C H, Lee Y J, . Freestanding high quality GaN substrate by associated GaN nanorods self-separated hydride vapor-phase epitaxy. Applied Physics Letters, 2009, 95(5): 051905

[12] Motoki K, Okahisa T, Nakahata S, . Preparation of large GaN substrates. Materials Science and Engineering B, 2002, 93(1‒3): 123–130

[13] Zhang L, Shao Y, Hao X, . Improvement of crystal quality HVPE grown GaN on an H₃PO₄ etched template. CrystEngComm, 2011, 13(15): 5001–5004

[14] Zhang L, Dai Y, Wu Y, . Epitaxial growth of a self-separated GaN crystal by using a novel high temperature annealing porous template. CrystEngComm, 2014, 16(38): 9063–9068

[15] Gogova D, Kasic A, Larsson H, . Strain-free bulk-like GaN grown by hydride-vapor-phase-epitaxy on two-step epitaxial lateral overgrown GaN template. Journal of Applied Physics, 2004, 96(1): 799–806

[16] Gibart B, Beaumont P, Vennegues P. Nitride semiconductors. In: Ruterana P, Albrecht M, Neugebauer J, eds. Handbook on Materials and Devices. Weinheim, Germany: Wiley-VCH, 2003, 45

[17] Tian Y, Shao Y, Wu Y, . Direct growth of freestanding GaN on C-face SiC by HVPE. Scientific Reports, 2015, 5(1): 10748

[18] Tripathy S, Chua S J, Chen P, . Micro-Raman investigation of strain in GaN and Al_xGa_1−xN/GaN heterostructures grown on Si(111). Journal of Applied Physics, 2002, 92(7): 3503–3510

[19] Kisielowski C, Krüger J, Ruvimov S, . Strain-related phenomena in GaN thin films. Physical Review B: Condensed Matter, 1996, 54(24): 17745–17753

[20] Boguslawski P, Briggs E L, Bernholc J. Native defects in gallium nitride. Physical Review B, 1995, 51(23): 17255–17258

[21] Xu F J, Shen B, Lu L, . Different origins of the yellow luminescence in as-grown high-resistance GaN and unintentional-doped GaN films. Journal of Applied Physics, 2010, 107(2): 023528

[22] Lyons J L, Janotti A, Van de Walle C G. Carbon impurities and the yellow luminescence in GaN. Applied Physics Letters, 2010, 97(15): 152108

[23] Ambacher O, Brandt M S, Dimitrov R, . Thermal stability and desorption of Group III nitrides prepared by metal organic chemical vapor deposition. Journal of Vacuum Science & Technology B, 1996, 14(6): 3532–3542

[24] Rebey A, Boufaden T, El Jani B. In situ optical monitoring of the decomposition of GaN thin films. Journal of Crystal Growth, 1999, 203(1‒2): 12–17

[25] L’vov B V. Kinetics and mechanism of thermal decomposition of GaN. Thermochimica Acta, 2000, 360(1): 85–91

[26] Shao Y, Zhang L, Hao X, . Large area stress distribution in crystalline materials calculated from lattice deformation identified by electron backscatter diffraction. Scientific Reports, 2014, 4: 5934 (5 pages)

[27] Shao Y, Dai Y, Hao X, . EBSD crystallographic orientation research on strain distribution in hydride vapor phase epitaxy GaN grown on patterned substrate. CrystEngComm, 2013, 15(39): 7965–7969

[28] Wilkinson A J, Hirsh P B. Electron diffraction based techniques in scanning electron microscopy of bulk materials. Micron, 1997, 28: 279–308

[29] Stanford N, Dunne D, Ferry M. Deformation and annealing of (011)[011] oriented Al single crystals. Acta Materialia, 2003, 51(3): 665–676

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