J. Semicond. >  In Press

ARTICLES

8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy

Ruihua Zhang1, Fang Liu2, , Yao Wu1, Hongfen Xu1, Jinmi He1, Ming Liu1, Jianhui Wang1, Kunyang Li2, Ping Wang2, Jiejun Wu2, Tongjun Yu2, Qi Wang3, Jingquan Lu1, , Guoyi Zhang1, 2, 3 and Xinqiang Wang2, 3,

+ Author Affiliations

 Corresponding author: Fang Liu, liu-fang@pku.edu.cn; Jingquan Lu, snszl2013@sinonitride.com; Xinqiang Wang, wangshi@pku.edu.cn

DOI: 10.1088/1674-4926/25100017CSTR: 10.1088/1674-4926/25100017

PDF

Turn off MathJax

Abstract: The absence of large-size gallium nitride (GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN substrates grown by hydride vapor phase epitaxy. Critical to this achievement is the improvement in gas-flow uniformity, which ensures exceptional thickness homogeneity and enables the crack-free growth of GaN. After laser lift-off (LLO) separation, the freestanding GaN substrate exhibits superior crystal quality, evidenced by full width at half maximum values of 68 and 54 arcsec for X-ray diffraction rocking curves of (002) and (102) planes, alongside a low dislocation density of 1.6 × 106 cm−2. This approach establishes a robust pathway for the production of large-size GaN substrates, which are essential for advancing next-generation power electronics and high-efficiency photonics.

Key words: gallium nitride, single-crystal substrates, large size, hydride vapor phase epitaxy



[1]
Amano H. Nobel Lecture: Growth of GaN on sapphire via low-temperature deposited buffer layer and realization of p-type GaN by Mg doping followed by low-energy electron beam irradiation. Rev Mod Phys, 2015, 87(4), 1133 doi: 10.1103/RevModPhys.87.1133
[2]
Nakamura S. Nobel Lecture: Background story of the invention of efficient blue InGaN light emitting diodes. Rev Mod Phys, 2015, 87(4), 1139 doi: 10.1103/RevModPhys.87.1139
[3]
Sun Y, Zhou K, Sun Q, et al. Room-temperature continuous-wave electrically injected InGaN-based laser directly grown on Si. Nat Photonics, 2016, 10, 595 doi: 10.1038/nphoton.2016.158
[4]
Chen Z Y, Sheng B W, Liu F, et al. High-efficiency InGaN red mini-LEDs on sapphire toward full-color nitride displays: Effect of strain modulation. Adv Funct Materials, 2023, 33(26), 2300042 doi: 10.1002/adfm.202300042
[5]
Yao Y X, Huang S, Cao R Y, et al. Dislocation-assisted electron and hole transport in GaN epitaxial layers. Nat Commun, 2025, 16(1), 6448 doi: 10.1038/s41467-025-61510-w
[6]
Ho C H, Speck J S, Weisbuch C, et al. Efficiency and forward voltage of blue and green lateral LEDs with V-shaped defects and random alloy fluctuation in quantum wells. Phys Rev Applied, 2022, 17, 014033 doi: 10.1103/PhysRevApplied.17.014033
[7]
Nakamura S. The roles of structural imperfections in InGaN-based blue light-emitting diodes and laser diodes. Science, 1998, 281(5379), 956 doi: 10.1126/science.281.5379.956
[8]
Liu F, Zhang Z H, Rong X, et al. Graphene-assisted epitaxy of nitrogen lattice polarity GaN films on non-polar sapphire substrates for green light emitting diodes. Adv Funct Materials, 2020, 30(22), 2001283 doi: 10.1002/adfm.202001283
[9]
Xu Y, Cao B, He S Y, et al. Evolution of threading dislocations in GaN epitaxial laterally overgrown on GaN templates using self-organized graphene as a nano-mask. Appl Phys Lett, 2017, 111(10), 102105 doi: 10.1063/1.4998924
[10]
Ji Q B, Li L, Zhang W, et al. Dislocation reduction and stress relaxation of GaN and InGaN multiple quantum wells with improved performance via serpentine channel patterned mask. ACS Appl Mater Interfaces, 2016, 8(33), 21480 doi: 10.1021/acsami.6b07044
[11]
Boćkowski M, Grzegory I. Recent progress in crystal growth of bulk GaN. Acta Phys Pol A, 2022, 141(3), 167 doi: 10.12693/APhysPolA.141.167
[12]
Xu K, Wang J F, Ren G Q. Progress in bulk GaN growth. Chin Phys B, 2015, 24(6), 066105 doi: 10.1088/1674-1056/24/6/066105
[13]
Wu J J, Wang K, Yu T J, et al. GaN substrate and GaN homo-epitaxy for LEDs: Progress and challenges. Chin Phys B, 2015, 24(6), 068106 doi: 10.1088/1674-1056/24/6/068106
[14]
Freitas J A Jr, Culbertson J C, Mahadik N A, et al. Growth of high crystalline quality HVPE-GaN crystals with controlled electrical properties. Cryst Growth Des, 2015, 15(10), 4837 doi: 10.1021/acs.cgd.5b00617
[15]
Wu C P, Soomro A M, Sun F P, et al. Large-roll growth of 25-inch hexagonal BN monolayer film for self-release buffer layer of free-standing GaN wafer. Sci Rep, 2016, 6, 34766 doi: 10.1038/srep34766
[16]
Liu Q, Zając M, Iwińska M, et al. Carbon doped semi-insulating freestanding GaN crystals by ethylene. Appl Phys Lett, 2022, 121, 172103 doi: 10.1063/5.0118250
[17]
Ma Q, Ando Y, Tanaka A, et al. Evaluation of electroluminescence of AlGaN/GaN HEMT on free-standing GaN substrate. Appl Phys Express, 2022, 15(9), 094004 doi: 10.35848/1882-0786/ac8782
[18]
Liang Z W, Liu S F, Yuan Y, et al. High quality 6-inch single-crystalline AlN template for E-mode HEMT power device. J Semicond, 2025, 46(3), 032501 doi: 10.1088/1674-4926/24100041
[19]
Kaneki S, Konno T, Mori H, et al. Quartz-free hydride vapor phase epitaxy for production of large size GaN-on-GaN epitaxial wafers. Appl Phys Express, 2025, 18(5), 055502 doi: 10.35848/1882-0786/adce53
[20]
Cheng Y T, Liu P, Wu J J, et al. High uniform growth of 4-inch GaN wafer via flow field optimization by HVPE. J Cryst Growth, 2016, 445, 24 doi: 10.1016/j.jcrysgro.2016.04.010
[21]
Wu Y Z, Chen C M, Yu J X, et al. Optimizing HVPE flow field to achieve GaN crystal uniform growth. J Cryst Growth, 2023, 614, 127214 doi: 10.1016/j.jcrysgro.2023.127214
[22]
Chen M, Zhang J Y, Lv X Q, et al. Effect of laser pulse width on the laser lift-off process of GaN films. Chin Phys Lett, 2013, 30(1), 014203 doi: 10.1088/0256-307X/30/1/014203
[23]
Miyoshi M, Watanabe A, Egawa T. Modeling of the wafer bow in GaN-on-Si epiwafers employing GaN/AlN multilayer buffer structures. Semicond Sci Technol, 2016, 31(10), 105016 doi: 10.1088/0268-1242/31/10/105016
[24]
Liu N L, Wu J J, Li W H, et al. Highly uniform growth of 2-inch GaN wafers with a multi-wafer HVPE system. J Cryst Growth, 2014, 388, 132 doi: 10.1016/j.jcrysgro.2013.11.023
[25]
Raghavan S, Redwing J. Growth stresses and cracking in GaN films on (111) Si grown by metalorganic chemical vapor deposition. II. Graded AlGaN buffer layers. J Appl Phys, 2005, 98, 023515 doi: 10.1063/1.1978991
[26]
Kang S M, Chang J, Lim J, et al. Graphene-enabled laser lift-off for ultrathin displays. Nat Commun, 2024, 15(1), 8288 doi: 10.1038/s41467-024-52661-3
[27]
Zhu T T, Oliver R A. Unintentional doping in GaN. Phys Chem Chem Phys, 2012, 14(27), 9558 doi: 10.1039/c2cp40998d
[28]
Puchtler T J, Woolf A, Zhu T T, et al. Effect of threading dislocations on the quality factor of InGaN/GaN microdisk cavities. ACS Photonics, 2015, 2(1), 137 doi: 10.1021/ph500426g
Fig. 1.  (Color online) Enhanced gas-flow uniformity enables crack-free growth of 8-inch GaN thick film by HVPE. (a) and (b) Before optimization: conventional nozzle schematic (a) and the resulting ~20-µm-thick GaN film with an inhomogeneity of 14.3% (b). (c) Photographs of ~470-µm-thick GaN films: severe cracking with the conventional nozzle. (d) and (e) After optimization: modified nozzle featuring an inner dilution (ID) N2 channel (d) and the corresponding ~20-µm-thick GaN film with an inhomogeneity of 3.9% (e). (f) Photographs of ~470-µm-thick GaN films: a crack-free result with the optimized nozzle design.

DownLoad: Full-Size Img PowerPoint
Fig. 2.  (Color online) Comparison of LLO processes at low temperature and high temperature. (a) Low temperature LLO (~500 °C) induces cracking due to wafer bowing and stress. (b) High temperature LLO (~800 °C) in a N2 ambient enables intact separation by reducing wafer bowing and stress. (c) Photograph of the cracked 8-inch GaN film after low-temperature LLO. (d) Photograph of the crack-free, 8-inch released GaN film after high-temperature LLO. The GaN structure consists of a ~5-μm-thick MOCVD-grown layer and a ~465-μm-thick HVPE-grown layer.

DownLoad: Full-Size Img PowerPoint
Fig. 3.  (Color online) Surface morphology and crystal quality characterization of the 8-inch FS-GaN substrate. (a) Photograph of the polished FS-GaN substrate, exhibiting a transparent and smooth surface. (b) and (c) Optical microscopy (b) and AFM (c) images of the surface. (d) FWHM values of X-ray rocking curves for the (002) and (102) reflections. (e) and (f) Spatial uniformity of the crystal quality, demonstrated by 37-point FWHM mapping for the (002) (e) and (102) (f) reflections across the 8-inch wafer. The 37 test positions on the 8-inch wafer are indicated. The thickness of the 8-inch FS-GaN substrate is about 470 µm.

DownLoad: Full-Size Img PowerPoint
Fig. 4.  (Color online) Dislocation density and scalability of as-fabricated FS-GaN substrates. (a) Cross-sectional CL image identifying the distinct GaN layers: MOCVD-grown GaN layer, HVPE-grown GaN-Ⅰ and GaN-Ⅱ layers. (b) Plan-view CL image quantifying the threading dislocation density. (c) Dislocation distribution confirmed by 37-point CL mapping. (d) Photograph demonstrating successful fabrication across 2-inch to 8-inch scales.

DownLoad: Full-Size Img PowerPoint
[1]
Amano H. Nobel Lecture: Growth of GaN on sapphire via low-temperature deposited buffer layer and realization of p-type GaN by Mg doping followed by low-energy electron beam irradiation. Rev Mod Phys, 2015, 87(4), 1133 doi: 10.1103/RevModPhys.87.1133
[2]
Nakamura S. Nobel Lecture: Background story of the invention of efficient blue InGaN light emitting diodes. Rev Mod Phys, 2015, 87(4), 1139 doi: 10.1103/RevModPhys.87.1139
[3]
Sun Y, Zhou K, Sun Q, et al. Room-temperature continuous-wave electrically injected InGaN-based laser directly grown on Si. Nat Photonics, 2016, 10, 595 doi: 10.1038/nphoton.2016.158
[4]
Chen Z Y, Sheng B W, Liu F, et al. High-efficiency InGaN red mini-LEDs on sapphire toward full-color nitride displays: Effect of strain modulation. Adv Funct Materials, 2023, 33(26), 2300042 doi: 10.1002/adfm.202300042
[5]
Yao Y X, Huang S, Cao R Y, et al. Dislocation-assisted electron and hole transport in GaN epitaxial layers. Nat Commun, 2025, 16(1), 6448 doi: 10.1038/s41467-025-61510-w
[6]
Ho C H, Speck J S, Weisbuch C, et al. Efficiency and forward voltage of blue and green lateral LEDs with V-shaped defects and random alloy fluctuation in quantum wells. Phys Rev Applied, 2022, 17, 014033 doi: 10.1103/PhysRevApplied.17.014033
[7]
Nakamura S. The roles of structural imperfections in InGaN-based blue light-emitting diodes and laser diodes. Science, 1998, 281(5379), 956 doi: 10.1126/science.281.5379.956
[8]
Liu F, Zhang Z H, Rong X, et al. Graphene-assisted epitaxy of nitrogen lattice polarity GaN films on non-polar sapphire substrates for green light emitting diodes. Adv Funct Materials, 2020, 30(22), 2001283 doi: 10.1002/adfm.202001283
[9]
Xu Y, Cao B, He S Y, et al. Evolution of threading dislocations in GaN epitaxial laterally overgrown on GaN templates using self-organized graphene as a nano-mask. Appl Phys Lett, 2017, 111(10), 102105 doi: 10.1063/1.4998924
[10]
Ji Q B, Li L, Zhang W, et al. Dislocation reduction and stress relaxation of GaN and InGaN multiple quantum wells with improved performance via serpentine channel patterned mask. ACS Appl Mater Interfaces, 2016, 8(33), 21480 doi: 10.1021/acsami.6b07044
[11]
Boćkowski M, Grzegory I. Recent progress in crystal growth of bulk GaN. Acta Phys Pol A, 2022, 141(3), 167 doi: 10.12693/APhysPolA.141.167
[12]
Xu K, Wang J F, Ren G Q. Progress in bulk GaN growth. Chin Phys B, 2015, 24(6), 066105 doi: 10.1088/1674-1056/24/6/066105
[13]
Wu J J, Wang K, Yu T J, et al. GaN substrate and GaN homo-epitaxy for LEDs: Progress and challenges. Chin Phys B, 2015, 24(6), 068106 doi: 10.1088/1674-1056/24/6/068106
[14]
Freitas J A Jr, Culbertson J C, Mahadik N A, et al. Growth of high crystalline quality HVPE-GaN crystals with controlled electrical properties. Cryst Growth Des, 2015, 15(10), 4837 doi: 10.1021/acs.cgd.5b00617
[15]
Wu C P, Soomro A M, Sun F P, et al. Large-roll growth of 25-inch hexagonal BN monolayer film for self-release buffer layer of free-standing GaN wafer. Sci Rep, 2016, 6, 34766 doi: 10.1038/srep34766
[16]
Liu Q, Zając M, Iwińska M, et al. Carbon doped semi-insulating freestanding GaN crystals by ethylene. Appl Phys Lett, 2022, 121, 172103 doi: 10.1063/5.0118250
[17]
Ma Q, Ando Y, Tanaka A, et al. Evaluation of electroluminescence of AlGaN/GaN HEMT on free-standing GaN substrate. Appl Phys Express, 2022, 15(9), 094004 doi: 10.35848/1882-0786/ac8782
[18]
Liang Z W, Liu S F, Yuan Y, et al. High quality 6-inch single-crystalline AlN template for E-mode HEMT power device. J Semicond, 2025, 46(3), 032501 doi: 10.1088/1674-4926/24100041
[19]
Kaneki S, Konno T, Mori H, et al. Quartz-free hydride vapor phase epitaxy for production of large size GaN-on-GaN epitaxial wafers. Appl Phys Express, 2025, 18(5), 055502 doi: 10.35848/1882-0786/adce53
[20]
Cheng Y T, Liu P, Wu J J, et al. High uniform growth of 4-inch GaN wafer via flow field optimization by HVPE. J Cryst Growth, 2016, 445, 24 doi: 10.1016/j.jcrysgro.2016.04.010
[21]
Wu Y Z, Chen C M, Yu J X, et al. Optimizing HVPE flow field to achieve GaN crystal uniform growth. J Cryst Growth, 2023, 614, 127214 doi: 10.1016/j.jcrysgro.2023.127214
[22]
Chen M, Zhang J Y, Lv X Q, et al. Effect of laser pulse width on the laser lift-off process of GaN films. Chin Phys Lett, 2013, 30(1), 014203 doi: 10.1088/0256-307X/30/1/014203
[23]
Miyoshi M, Watanabe A, Egawa T. Modeling of the wafer bow in GaN-on-Si epiwafers employing GaN/AlN multilayer buffer structures. Semicond Sci Technol, 2016, 31(10), 105016 doi: 10.1088/0268-1242/31/10/105016
[24]
Liu N L, Wu J J, Li W H, et al. Highly uniform growth of 2-inch GaN wafers with a multi-wafer HVPE system. J Cryst Growth, 2014, 388, 132 doi: 10.1016/j.jcrysgro.2013.11.023
[25]
Raghavan S, Redwing J. Growth stresses and cracking in GaN films on (111) Si grown by metalorganic chemical vapor deposition. II. Graded AlGaN buffer layers. J Appl Phys, 2005, 98, 023515 doi: 10.1063/1.1978991
[26]
Kang S M, Chang J, Lim J, et al. Graphene-enabled laser lift-off for ultrathin displays. Nat Commun, 2024, 15(1), 8288 doi: 10.1038/s41467-024-52661-3
[27]
Zhu T T, Oliver R A. Unintentional doping in GaN. Phys Chem Chem Phys, 2012, 14(27), 9558 doi: 10.1039/c2cp40998d
[28]
Puchtler T J, Woolf A, Zhu T T, et al. Effect of threading dislocations on the quality factor of InGaN/GaN microdisk cavities. ACS Photonics, 2015, 2(1), 137 doi: 10.1021/ph500426g

    • Search

    Advanced Search >>

    GET CITATION

    shu

    Export: BibTex EndNote

    Article Metrics

    Article views: 44 Times PDF downloads: 14 Times Cited by: 0 Times

    History

    Received: 20 October 2025 Revised: 05 November 2025 Online: Accepted Manuscript: 17 November 2025Uncorrected proof: 18 November 2025

    Catalog

      Email This Article

      User name:
      Email:*请输入正确邮箱
      Code:*验证码错误
      Send
      Article Navigation >  Journal of Semiconductors  > 2026  > Uncorrected proof
      Ruihua Zhang, Fang Liu, Yao Wu, Hongfen Xu, Jinmi He, Ming Liu, Jianhui Wang, Kunyang Li, Ping Wang, Jiejun Wu, Tongjun Yu, Qi Wang, Jingquan Lu, Guoyi Zhang, Xinqiang Wang. 8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/25100017 ****R H Zhang, F Liu, Y Wu, H F Xu, J M He, M Liu, J H Wang, K Y Li, P Wang, J J Wu, T J Yu, Q Wang, J Q Lu, G Y Zhang, and X Q Wang, 8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy[J]. J. Semicond., 2026, 47(2), 022501 doi: 10.1088/1674-4926/25100017
      Citation:
      Ruihua Zhang, Fang Liu, Yao Wu, Hongfen Xu, Jinmi He, Ming Liu, Jianhui Wang, Kunyang Li, Ping Wang, Jiejun Wu, Tongjun Yu, Qi Wang, Jingquan Lu, Guoyi Zhang, Xinqiang Wang. 8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/25100017 ****
      R H Zhang, F Liu, Y Wu, H F Xu, J M He, M Liu, J H Wang, K Y Li, P Wang, J J Wu, T J Yu, Q Wang, J Q Lu, G Y Zhang, and X Q Wang, 8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy[J]. J. Semicond., 2026, 47(2), 022501 doi: 10.1088/1674-4926/25100017
      shu

      8-inch free-standing GaN substrates grown by hydride vapor phase epitaxy

      DOI: 10.1088/1674-4926/25100017
      CSTR: 10.1088/1674-4926/25100017
      • 1.

        Sino Nitride Semiconductor Co. Ltd., Dongguan 523518, China

      • 2.

        State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China

      • 3.

        Dongguan Institute of Opto-Electronics, Peking University, Dongguan 571539, China

      More Information
      • Ruihua Zhang is the Director of R & D at Sino Nitride Semiconductor Co., Ltd. He specializes in MOCVD and HVPE growth of GaN-based semiconductor materials and laser lift-off optimization. He also leads R & D projects for free-standing GaN substrates ranging from 2 to 8 inches in size
      • Fang Liu is a research associate professor in the School of Physics at Peking University. He received his B.S. degree from Jilin University and his Ph.D. from Peking University. His research focuses on the epitaxial growth of Ⅲ-nitride semiconductors, interface engineering, and their applications in light-emitting devices
      • Jingquan Lu received his bachelor’s degree from Sun Yat-Sen University in 2008 and his master’s degree from the same university in 2011. He is currently a consultant at Sino Nitride Semi-conductor Co. Ltd., specializing in cutting-edge research on GaN material growth technologies
      • Xinqiang Wang is a full Professor of School of Physics at Peking University. He joined the faculty in May 2008, after more than 6 years of postdoctoral research at Chiba University and Japan Science Technology Agency, Japan. He mainly concentrates on Ⅲ-nitride semiconductors, including epitaxy and device fabrication. He is an Optica Fellow and a Chinese Optical Society (COS) Fellow
      • Corresponding author: liu-fang@pku.edu.cn; snszl2013@sinonitride.com; wangshi@pku.edu.cn
      • Received Date: 2025-10-20
      • Revised Date: 2025-11-05
        • Available Online: 2025-11-17

      Catalog

        Journal of Semiconductors © 2017 All Rights Reserved   京ICP备05085259号-2

        /

        DownLoad:  Full-Size Img  PowerPoint
        Return
        Return