[1] [1] Mukai T, Takekawa K, Nakamura S. InGaNbased blue lightemitting diodes grown on epitaxially laterally overgrown GaN substrates［J］. Japanese Journal of Applied Physics, 1998, 37(7b): L839L841.

[2] [2] Akasaki I, Amano H. Breakthroughs in improving crystal quality of GaN and invention of the pn junction bluelightemitting diode［J］. Japanese Journal of Applied Physics, 2006, 45(12): 90019010.

[3] [3] Zhao Y J, Fu H Q, Wang G T, et al. Toward ultimate efficiency: progress and prospects on planar and 3D nanostructured nonpolar and semipolar InGaN lightemitting diodes［J］. Advances in Optics and Photonics, 2018, 10(1): 246.

[4] [4] Queren D, Avramescu A, Bruderl G, et al. 500 nm electrically driven InGaN based laser diodes［J］. Applied Physics Letters, 2009, 94(8): 081119.

[5] [5] Pearton S J， Ren F， Zhang A P, et al. Fabrication and performance of GaN electronic devices［J］. Materials Science and Engineering R: Reports, 2000, 30(3/4/5/6): 55212.

[6] [6] Efthymiou L, Longobardi G, Camuso G, et al. On the physical operation and optimization of the pGaN gate in normallyoff GaN HEMT devices［J］. Applied Physics Letters, 2017, 110(12): 123502.

[7] [7] Anderson T J, Chowdhury S, Aktas O, et al. GaN power devicescurrent status and future directions［J］. The Electrochemical Society Interface,2018, 27(4): 4347.

[8] [8] Liu L, Edgar J H. Substrates for gallium nitride epitaxy［J］. Materials Science and Engineering: R: Reports, 2002, 37(3): 61127.

[9] [9] Scholz F. Semipolar GaN grown on foreign substrates: a review［J］. Semiconductor Science and Technology, 2012, 27(2): 024002.

[10] [10] Yim W M, Paff R J. Thermal expansion of AlN, sapphire, and silicon［J］. Journal of Applied Physics, 1974, 45(3): 14561457.

[11] [11] Leszczynski M, Suski T, Teisseyre H, et al. Thermal expansion of gallium nitride［J］. Journal of Applied Physics, 1994, 76(8): 49094911.

[12] [12] Usami S, Ando Y, Tanaka A, et al. Correlation between dislocations and leakage current of pn diodes on a freestanding GaN substrate［J］. Applied Physics Letters, 2018, 112(18): 182106.

[13] [13] Bockowski M. High nitrogen pressure solution growth of GaN［J］. Japanese Journal of Applied Physics, 2014, 53(10): 100203.

[14] [14] Wang B G, Callahan M J. Ammonothermal synthesis of IIINitride crystals［J］. Crystal Growth & Design, 2006, 6(6): 12271246.

[15] [15] Zhang S Y, Hintze F, Schnick W, et al. Intermediates in ammonothermal GaN crystal growth under ammonoacidic conditions［J］. European Journal of Inorganic Chemistry, 2013, 2013(31): 53875399.

[16] [16] Ehrentraut D, Kagamitani Y, Yokoyama C, et al. Physicochemical features of the acid ammonothermal growth of GaN［J］. Journal of Crystal Growth, 2008, 310(5): 891895.

[17] [17] Yoshida K, Aoki K, Fukuda T. Hightemperature acidic ammonothermal method for GaN crystal growth［J］. Journal of Crystal Growth, 2014, 393: 9397.

[18] [18] Hashimoto T, Saito M, Fujito K, et al. Seeded growth of GaN by the basic ammonothermal method［J］. Journal of Crystal Growth, 2007, 305(2): 311316.

[19] [19] Ehrentraut D, Fukuda T. Ammonothermal crystal growth of gallium nitrideA brief discussion of critical issues［J］. Journal of Crystal Growth, 2010, 312(18): 25142518.

[20] [20] Tomida D, Kuribayashi T, Suzuki K, et al. Effect of halogen species of acidic mineralizer on solubility of GaN in supercritical ammonia［J］. Journal of Crystal Growth, 2011, 325(1): 5254.

[21] [21] Bao Q X, Saito M, Hazu K J, et al. Ammonothermal crystal growth of GaN using an NH4F mineralizer［J］. Crystal Growth & Design, 2013, 13(10): 41584161.

[22] [22] Dwilinski R, Doradzinski R, Garczynski J, et al. Excellent crystallinity of truly bulk ammonothermal GaN［J］. Journal of Crystal Growth, 2008, 310(17)： 39113916.

[23] [23] Tomida D, Kuroda K, Nakamura K, et al. Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer［J］. Chemistry Central Journal, 2018, 12(1)： 16.

[24] [24] Dwilinski R, Wysmolek A, Baranowski J, et al. GaN synthesis by ammonothermal method［J］. Acta Physica Polonica A, 1995, 88(5)： 833836.

[25] [25] Hashimoto T, Fujito K, Saito M, et al. Ammonothermal growth of GaN on an over1inch seed crystal［J］. Japanese Journal of Applied Physics, 2005, 44: L1570L1572.

[26] [26] Wang B G, Callahan M J, Rakes K D, et al. Ammonothermal growth of GaN crystals in alkaline solutions［J］. Journal of Crystal Growth, 2006, 287(2): 376380.

[27] [27] Hashimoto T, Feng W, Speck J S, et al. Growth of bulk GaN crystals by the basic ammonothermal method［J］. Japanese Journal of Applied Physics, 2007: L889L891.

[28] [28] Dwilinski R, Doradzinski R, Garczynski J, et al. Properties of truly bulk GaN monocrystals grown by ammonothermal method［J］. Physica Status Solidi (c), 2009,6(12): 26612664.

[29] [29] Bulk GaN: Ammonothermal trumps HVPE［J］. Compound Semiconductor, 2010, 2: 1216.

[30] [30] Kyma responds to CS article entitled “Bulk GaN: Ammonothermal trumps HVPE”［J］. Compound Semiconductor, 2010, 3: 93.

[31] [31] Dwilinski R, Doradzinski R, Garczynski J, et al. Recent achievements in AMMONObulk method［J］. Journal of Crystal Growth, 2010, 312(18): 24992502.

[32] [32] Zajac M, Kucharski R, Grabianska K, et al. Basic ammonothermal growth of gallium nitridestate of the art, challenges, perspectives［J］. Progress in Crystal Growth and Characterization of Materials, 2018, 64(3): 6374.

[33] [33] Pimputkar S, Kawabata S, Speck J S, et al. Improved growth rates and purity of basic ammonothermal GaN［J］. Journal of Crystal Growth, 2014, 403:717.

[34] [34] Hashimoto T, Letts E R, Key D, et al. Two inch GaN substrates fabricated by the near equilibrium ammonothermal (NEAT) method［J］. Japanese Journal of Applied Physics, 2019, 588(SC)： SC1005.

[35] [35] Kucharski R, Zajac M, Doradzinski R, et al. Nonpolar and semipolar ammonothermal GaN substrates［J］. Semiconductor Science and Technology, 2012: 024007.

[36] [36] Li T K, Ren G Q, Su X J, et al. Growth behavior of ammonothermal GaN crystals grown on nonpolar and semipolar HVPE GaN seeds［J］.CrystEngComm, 2019, 33(33):48744879.

[37] [37] Pimputkar S, Suihkonen S, Imade M, et al. Free electron concentration dependent subbandgap optical absorption characterization of bulk GaN crystals［J］. Journal of Crystal Growth, 2015, 432: 4953.

[38] [38] Sintonen S, Kivisaari P, Pimputkar S, et al. Incorporation and effects of impurities in different growth zones within basic ammonothermal GaN［J］. Journal of Crystal Growth, 2016, 456: 4350.

[39] [39] Krysko M, Sarzynski M, Domagala J, et al. The influence of lattice parameter variation on microstructure of GaN single crystals［J］. Journal of Alloys Compounds, 2005, 401(1/2)： 261.

[40] [40] van de Walle Chris G. Effects of impurities on the lattice parameters of GaN［J］. Physical Review B, 2003, 68(16): 165209.

[41] [41] Darakchieva V, Monemar B, Usui A. On the lattice parameters of GaN［J］. Applied Physics Letters, 2007, 91(3): 031911.

[42] [42] Jezowski A, Churiukova O, Mucha J, et al. Thermal conductivity of heavily doped bulk crystals GaN:O. Free carriers contribution［J］. Materials Research Express, 2015, 2(8): 085902.

[43] [43] Tuomisto F, Makkonen I. Defect identification in semiconductors with positron annihilation: experiment and theory［J］. Reviews of Modern Physics, 2013, 85(4): 1583.

[44] [44] Purdy A P, Jouet R J, George C F. Ammonothermal recrystallization of gallium nitride with acidic mineralizers［J］. Crystal Growth and Design, 2002, 2(2): 141145.

[45] [45] Purdy A P. Ammonothermal synthesis of cubic gallium nitride［J］. Chemistry of Materials, 1999, 11(7): 16481651.

[46] [46] Yoshikawa A, Ohshima E, Fukuda T H, et al.［J］. Journal of Crystal Growth, 2004, 260: 6772.

[47] [47] Kagamitani Y, Ehrentraut D, Yoshikawa A, et al. Ammonothermal epitaxy of thick GaN film using NH4Cl mineralizer［J］. Japanese Journal of Applied Physics, 2006, 45(5A)： 40184020.

[48] [48] Ehrentraut D， Kagamitani Y， Fukuda T, et al. Reviewing recent developments in the acid ammonothermal crystal growth of gallium nitride［J］. Journal of Crystal Growth, 2008, 310(17): 39023906.

[49] [49] Ehrentraut D, Pakalapati R T, Kamber D S, et al. High quality, low cost ammonothermal bulk GaN substrates［J］. Japanese Journal of Applied Physics, 2013, 52(8S)： 08 JA01.

[50] [50] Jiang W, Ehrentraut D, Kamber D S, et al. Ammonothermal bulk GaN substrates for LEDs［J］. Proc of SPIE, 2014, 9003: 900313.

[51] [51] Jiang W K， Ehrentraut D， Cook J, et al. Transparent, conductive bulk GaN by high temperature ammonothermal growth［J］. Physica Status Solid(b), 2015, 252(5): 10691074.

[52] [52] Mikawa Y, Ishinabe T, Kagamitani Y, et al. Recent progress of large size and low dislocation bulk GaN growth［C］//SPIE OPTO．Proc SPIE 11280， Gallium Nitride Materials and Devices XV， San Francisco， California， USA． 2020， 1128： 1128002.

[53] [53] Yamane H， Shimada M， Clarke S J， et al. Preparation of GaN single crystals using a Na flux［J］. Chemistry of Materials, 1997, 9(2):413416.

[54] [54] Kawamura F, Morishita M, Omae K, et al. Novel liquid phase epitaxy (LPE) growth method for growing large GaN single crystals: introduction of the flux film coatedliquid phase epitaxy (FFCLPE)method［J］. Japanese Journal of Applied Physics, 2003, 42(Part 2，No．8A)： L879L881.

[55] [55] Yoshida T， Imanishi M， Kitamura T, et al. Development of GaN substrate with a large diameter and small orientation deviation［J］. Physica Status Solidi (b), 2017, 254(8)： 1600671.

[56] [56] Yamane H, Kinno D, Shimada M, et al. GaN single crystal growth from a NaGa melt［J］. Journal of Materials Science, 2000, 35(4):801808.

[57] [57] Morishita M, Kawamura F, Kawahara M, et al. The influences of supersaturation on LPE growth of GaN single crystals using the Na flux method［J］. Journal of Crystal growth, 2004, 270(3/4): 402408.

[58] [58] Murakami K， Ogawa S， Imanishi M, et al. Increase in the growth rate of GaN crystals by using gaseous methane in the Na flux method［J］. Japanese Journal of Applied Physics, 2017, 56(5):055502

[59] [59] Morishita M, Kawamura F, Kawahara M, et al. Promoted nitrogen dissolution due to the addition of Li or Ca to GaNa melt: some effects of additives on the growth of GaN single crystals using the sodium flux method［J］. Journal of Crystal growth, 2005, 284(1/2): 9199.

[60] [60] Gejo R, Kawamura F, Kawahara M, et al. Effect of thermal convection on liquid phase epitaxy of GaN by Na flux method［J］. Japanese Journal of Applied Physics, 2007, 46(12): 76897692.

[61] [61] Kawamura F, Morishita M, Tanpo M, et al. Effect of carbon additive on increases in the growth rate of 2 in GaN single crystals in the Na flux method［J］. Journal of Crystal Growth, 2008, 310(17): 39463949.

[62] [62] Imade M, Murakami K, Matsuo D, et al. Centimetersized bulk GaN single crystals grown by the Naflux method with a necking technique［J］. Crystal Growth & Design, 2012, 12(7): 37993805.

[63] [63] Imade M, Imanishi M, Todoroki Y, et al. Fabrication of lowcurvature 2 in. GaN wafers by Naflux coalescence growth technique［J］. Applied Physics Express, 2014, 7(3): 035503.

[64] [64] Sato T, Nakamura K, Imanishi M, et al. Homoepitaxial growth of GaN crystals by Naflux dipping method［J］. Japanese Journal of Applied Physics, 2015, 54(10)：105501.

[65] [65] Imanishi M, Yoshida T, Kitamura T, et al. Homoepitaxial hydride vapor phase epitaxy growth on GaN wafers manufactured by the Naflux method［J］. Crystal Growth & Design, 2017, 17(7): 38063811.

[66] [66] Maruyama M, Nakamura K, Che S, et al. Fabrication of highquality {11-22} GaN substrates using the Na flux method［J］. Applied Physics Express, 2016, 9(5): 055501.

[67] [67] Yamada T, Imanishi M, Murakami K, et al. Fabrication of a 1.5inch freestanding GaN substrate by selective dissolution of sapphire using Li after the Naflux growth［J］. Journal of Crystal Growth, 2020, 533: 125462.

[68] [68] Liu Z L, Ren G Q, Shi L, et al. Effect of carbon types on the generation and morphology of GaN polycrystals grown using the Na flux method［J］. CrystEngComm, 2015, 17(5): 10301036.