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Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2

Xinwang Yao, Lizhi Cui, Junwei Zhang, Junhan Qian, Xiaoping Yang, Xiujuan Wang, Chunyan Wu and Linbao Luo

+ Author Affiliations

 Corresponding author: Chunyan Wu, cywu@hfut.edu.cn

DOI: 10.1088/1674-4926/26020066CSTR: 32376.14.1674-4926.26020066

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Abstract: In this article, a vertical SnO/β-Ga2O3 mesa heterojunction diode (mesa-HJD) fabricated through self-aligned etching is reported. The mesa structure eliminates the influence of lateral depletion at the region, leading to an improved breakdown characteristics in comparison with its unterminated heterojunction diode (UT-HJD) counterpart. The SnO/β-Ga2O3 mesa-HJD, featuring a 500 nm mesa depth, achieves a breakdown voltage (BV) of 1100 V, which can be improved to 1631 V by sidewall passivation. With the increase of mesa depth, BV increases, accompanied by the increase of specific on-resistance (Ron,sp). Therefore, a maximum Baliga’s power figure of merit (PFOM) can be achieved for the optimized device with 500 nm mesa depth, giving the value of 0.93 GW/cm2 for the passivated device. The mesa-HJD demonstrates considerable potential for application in high BV β-Ga2O3 power electronic devices in the future.

Key words: β-Ga2O3, mesa heterojunction diode (mesa-HJD), power electronic device



[1]
Sun S H, Wang C L, Alghamdi S, et al. Recent advanced ultra-wide bandgap β-Ga2O3 material and device technologies. Adv Electron Mater, 2025, 11(1): 2300844 doi: 10.1002/aelm.202300844
[2]
Wong M H, Higashiwaki M. Vertical β-Ga2O3 power transistors: A review. IEEE Trans Electron Devices, 2020, 67(10): 3925 doi: 10.1109/TED.2020.3016609
[3]
Yang J C, Ahn S, Ren F, et al. High reverse breakdown voltage Schottky rectifiers without edge termination on Ga2O3. Appl Phys Lett, 2017, 110(19): 192101 doi: 10.1063/1.4983203
[4]
Li W S, Saraswat D, Long Y Y, et al. Near-ideal reverse leakage current and practical maximum electric field in β-Ga2O3 Schottky barrier diodes. Appl Phys Lett, 2020, 116(19): 192101 doi: 10.1063/5.0007715
[5]
Han Z, Jian G Z, Zhou X Z, et al. 2.7 kV low leakage vertical PtOx/β-Ga2O3 Schottky barrier diodes with self-aligned mesa termination. IEEE Electron Device Lett, 2023, 44(10): 1680 doi: 10.1109/LED.2023.3305389
[6]
Lu X, Zhou X D, Jiang H X, et al. 1-kV sputtered p-NiO/n-Ga2O3 heterojunction diodes with an ultra-low leakage current below 1 μA/cm2. IEEE Electron Device Lett, 2020, 41(3): 449 doi: 10.1109/LED.2020.2967418
[7]
Kokubun Y, Kubo S, Nakagomi S. All-oxide p–n heterojunction diodes comprising p-type NiO and n-type β-Ga2O3. Appl Phys Express, 2016, 9(9): 091101 doi: 10.7567/APEX.9.091101
[8]
Zheng R T, Feng W Y, Liao C, et al. P-IrOx/n-β-Ga2O3 heterojunction diodes with 1-kV breakdown and ultralow leakage current below 0.1 μA/cm2. IEEE Trans Electron Devices, 2024, 71(3): 1587
[9]
Watahiki T, Yuda Y, Furukawa A, et al. Heterojunction p-Cu2O/n-Ga2O3 diode with high breakdown voltage. Appl Phys Lett, 2017, 111(22): 222104 doi: 10.1063/1.4998311
[10]
Wu X, Huang C Y, Xu X X, et al. Band alignment of SnO/β-Ga2O3 heterojunction and its electrical properties for power device application. J Semicond, 2025, 46(8): 082503 doi: 10.1088/1674-4926/25020008
[11]
Than P H, Than T Q, Takaki Y. Breakdown voltage enhancement in p-GaAs/n-Ga2O3 heterojunction diodes with advanced termination designs. Phys Scr, 2025, 100(7): 075022 doi: 10.1088/1402-4896/addf8f
[12]
Roy S, Bhattacharyya A, Peterson C, et al. 2.1 kV (001)-β-Ga2O3 vertical Schottky barrier diode with high-k oxide field plate. Appl Phys Lett, 2023, 122(15): 152101 doi: 10.1063/5.0137935
[13]
Lin C H, Yuda Y, Wong M H, et al. Vertical Ga2O3 Schottky barrier diodes with guard ring formed by nitrogen-ion implantation. IEEE Electron Device Lett, 2019, 40(9): 1487 doi: 10.1109/LED.2019.2927790
[14]
Wang B Y, Xiao M, Spencer J, et al. 2.5 kV vertical Ga2O3 Schottky rectifier with graded junction termination extension. IEEE Electron Device Lett, 2023, 44(2): 221 doi: 10.1109/LED.2022.3229222
[15]
Lu X, Zhang X, Jiang H X, et al. Vertical β-Ga2O3 Schottky barrier diodes with enhanced breakdown voltage and high switching performance. Phys Status Solidi A, 2020, 217(3): 1900497 doi: 10.1002/pssa.201900497
[16]
Wu F H, Han Z, Liu J Y, et al. 8.7 A/700 V β-Ga2O3 Schottky barrier diode demonstrated by oxygen annealing combined with self-aligned mesa termination. Appl Phys Express, 2024, 17(3): 036504 doi: 10.35848/1882-0786/ad2d73
[17]
Xu X R, Deng Y C, Li T T, et al. Over 2 GW/cm2 low-conduction loss Ga2O3 vertical SBD with self-aligned field plate and mesa termination. Appl Phys Lett, 2024, 125(2): 022106 doi: 10.1063/5.0212785
[18]
Alfieri G, Mihaila A, Godignon P, et al. Deep level study of chlorine-based dry etched β-Ga2O3. J Appl Phys, 2021, 130(2): 025701 doi: 10.1063/5.0050416
[19]
Zhang Y H, Mei Z X, Wang T, et al. Flexible transparent high-voltage diodes for energy management in wearable electronics. Nano Energy, 2017, 40: 289 doi: 10.1016/j.nanoen.2017.08.025
[20]
Martínez-Angeles W L, González-Reynoso O, Carbajal-Arizaga G G, et al. Electronic barriers behavioral analysis of a Schottky diode structure featuring two-dimensional MoS2. Electronics, 2024, 13(20): 4008 doi: 10.3390/electronics13204008
[21]
Feng Y T, Zhou H, Ma J Y, et al. 120 A/1.78 kV p-Cr2O3/n-β-Ga2O3 heterojunction PN diodes with slanted mesa edge termination. IEEE Electron Device Lett, 2025, 46(10): 1705 doi: 10.1109/LED.2025.3598936
[22]
Zhao X X, Zhang S M, Shao G Q, et al. Over 450 V breakdown voltage in diamond vertical Schottky barrier diodes with anodic self-aligned mesa termination. Appl Phys Lett, 2025, 127(3): 032107 doi: 10.1063/5.0274905
[23]
Yang J C, Ren F, Khanna R, et al. Annealing of dry etch damage in metallized and bare (-201) Ga2O3. J Vac Sci Technol B, 2017, 35(5): 051201 doi: 10.1116/1.4986300
[24]
Sun Y, Kang X W, Zheng Y K, et al. Review of the recent progress on GaN-based vertical power Schottky barrier diodes (SBDs). Electronics, 2019, 8(5): 575 doi: 10.3390/electronics8050575
[25]
Dhara S, Kalarickal N K, Dheenan A, et al. β-Ga2O3 Schottky barrier diodes with 4.1 MV/cm field strength by deep plasma etching field-termination. Appl Phys Lett, 2022, 121(20): 203501 doi: 10.1063/5.0123284
[26]
Eifert B, Becker M, Reindl C T, et al. Raman studies of the intermediate tin-oxide phase. Phys Rev Mater, 2017, 1: 014602 doi: 10.1103/PhysRevMaterials.1.014602
[27]
Hudgins J L, Simin G S, Santi E, et al. An assessment of wide bandgap semiconductors for power devices. IEEE Trans Power Electron, 2003, 18(3): 907 doi: 10.1109/TPEL.2003.810840
[28]
Zhang L H, Verma A, Xing H G, et al. Inductively-coupled-plasma reactive ion etching of single-crystal β-Ga2O3. Jpn J Appl Phys, 2017, 56(3): 030304 doi: 10.7567/JJAP.56.030304
[29]
Wei S B, Hong Z F, Li C C, et al. Increase fixed charge at Al2O3/Ga2O3 interface for high-performance Ga2O3 trench Schottky barrier diodes by atomic nitrogen treatment. Appl Phys Lett, 2025, 126(15): 152108 doi: 10.1063/5.0254888
[30]
Zhong L H, Feng X, Zhang W H, et al. 2kV β-Ga2O3 Schottky diode with HfO2/SiO2 dual-layer field plate and mesa termination. Appl Phys Lett, 2025, 127(18): 182108 doi: 10.1063/5.0287147
[31]
Zhou F, Gong H H, Wang Z P, et al. Over 1.8 GW/cm2 beveled-mesa NiO/β-Ga2O3 heterojunction diode with 800 V/10 A nanosecond switching capability. Appl Phys Lett, 2025, 119(26): 262103 doi: 10.1063/5.0071280
[32]
Wu F H, Wen J P, Liu J Y, et al. Reliability of 1.5 × 1.5 mm2 β-Ga2O3 power diodes and application in DC–DC converter. Phys Status Solidi B, 2025, 262(8): 2400438
[33]
Xie S W, Alam M T, Gong J R, et al. 0.86 kV p-Si/(001)-Ga2O3 heterojunction diode. IEEE Electron Device Lett, 2024, 45(3): 444 doi: 10.1109/LED.2024.3352515
[34]
Xie S W, Sheikhi M, Xu S N, et al. P-GaAs/n-Ga2O3 heterojunction diode with breakdown voltage of ~800 V. Appl Phys Lett, 2024, 124(7): 073503 doi: 10.1063/5.0181056
[35]
Callahan W A, Egbo K, Lee C W, et al. Reliable operation of Cr2O3: Mg/β-Ga2O3 p–n heterojunction diodes at 600 °C. Appl Phys Lett, 2024, 124(15): 153504 doi: 10.1063/5.0185566
Fig. 1.  (Color online) (a) Schematic of SnO/β-Ga2O3 mesa-HJD. (b) Bird-view SEM image of a typical device and (c) EDS elemental mapping corresponding to the region marked by the square in (b). Scale bar: 2 μm.

DownLoad: Full-Size Img PowerPoint
Fig. 2.  (Color online) Typical forward J−V characteristics of the fabricated UT-HJD and mesa-HJD (mesa height: 500 nm) in (a) linear scale and (b) semi-log scale, the inset provides the calculated ideality factor for further analysis. (c) C−V and 1/C2−V characteristics of the UT-HJD and mesa-HJD at 500 kHz. (d) Reverse J−V characteristics of the UT-HJD and mesa-HJD, the inset shows the catastrophic breakdown of the device.

DownLoad: Full-Size Img PowerPoint
Fig. 3.  (Color online) (a) Forward and (b) reverse J−V characteristics of the mesa-HJD with different mesa depths. (c) PFOM of the UT-HJD and mesa-HJD with different mesa depth (500, 700 and 900 nm).

DownLoad: Full-Size Img PowerPoint
Fig. 4.  (Color online) (a) Simulated electric field distributions of the UT-HJD and mesa-HJD with different mesa depth (500 and 900 nm) under 500 V reverse bias. (b) Extracted electric field profiles along the vertical dashed line in panel (a).

DownLoad: Full-Size Img PowerPoint
Fig. 5.  (Color online) (a) Schematic of the passivated device. (b) Reverse J−V characteristics of the mesa-HJD and passivated device. (c) Benchmarking of the cutting-edge β-Ga2O3-based diodes.

DownLoad: Full-Size Img PowerPoint
[1]
Sun S H, Wang C L, Alghamdi S, et al. Recent advanced ultra-wide bandgap β-Ga2O3 material and device technologies. Adv Electron Mater, 2025, 11(1): 2300844 doi: 10.1002/aelm.202300844
[2]
Wong M H, Higashiwaki M. Vertical β-Ga2O3 power transistors: A review. IEEE Trans Electron Devices, 2020, 67(10): 3925 doi: 10.1109/TED.2020.3016609
[3]
Yang J C, Ahn S, Ren F, et al. High reverse breakdown voltage Schottky rectifiers without edge termination on Ga2O3. Appl Phys Lett, 2017, 110(19): 192101 doi: 10.1063/1.4983203
[4]
Li W S, Saraswat D, Long Y Y, et al. Near-ideal reverse leakage current and practical maximum electric field in β-Ga2O3 Schottky barrier diodes. Appl Phys Lett, 2020, 116(19): 192101 doi: 10.1063/5.0007715
[5]
Han Z, Jian G Z, Zhou X Z, et al. 2.7 kV low leakage vertical PtOx/β-Ga2O3 Schottky barrier diodes with self-aligned mesa termination. IEEE Electron Device Lett, 2023, 44(10): 1680 doi: 10.1109/LED.2023.3305389
[6]
Lu X, Zhou X D, Jiang H X, et al. 1-kV sputtered p-NiO/n-Ga2O3 heterojunction diodes with an ultra-low leakage current below 1 μA/cm2. IEEE Electron Device Lett, 2020, 41(3): 449 doi: 10.1109/LED.2020.2967418
[7]
Kokubun Y, Kubo S, Nakagomi S. All-oxide p–n heterojunction diodes comprising p-type NiO and n-type β-Ga2O3. Appl Phys Express, 2016, 9(9): 091101 doi: 10.7567/APEX.9.091101
[8]
Zheng R T, Feng W Y, Liao C, et al. P-IrOx/n-β-Ga2O3 heterojunction diodes with 1-kV breakdown and ultralow leakage current below 0.1 μA/cm2. IEEE Trans Electron Devices, 2024, 71(3): 1587
[9]
Watahiki T, Yuda Y, Furukawa A, et al. Heterojunction p-Cu2O/n-Ga2O3 diode with high breakdown voltage. Appl Phys Lett, 2017, 111(22): 222104 doi: 10.1063/1.4998311
[10]
Wu X, Huang C Y, Xu X X, et al. Band alignment of SnO/β-Ga2O3 heterojunction and its electrical properties for power device application. J Semicond, 2025, 46(8): 082503 doi: 10.1088/1674-4926/25020008
[11]
Than P H, Than T Q, Takaki Y. Breakdown voltage enhancement in p-GaAs/n-Ga2O3 heterojunction diodes with advanced termination designs. Phys Scr, 2025, 100(7): 075022 doi: 10.1088/1402-4896/addf8f
[12]
Roy S, Bhattacharyya A, Peterson C, et al. 2.1 kV (001)-β-Ga2O3 vertical Schottky barrier diode with high-k oxide field plate. Appl Phys Lett, 2023, 122(15): 152101 doi: 10.1063/5.0137935
[13]
Lin C H, Yuda Y, Wong M H, et al. Vertical Ga2O3 Schottky barrier diodes with guard ring formed by nitrogen-ion implantation. IEEE Electron Device Lett, 2019, 40(9): 1487 doi: 10.1109/LED.2019.2927790
[14]
Wang B Y, Xiao M, Spencer J, et al. 2.5 kV vertical Ga2O3 Schottky rectifier with graded junction termination extension. IEEE Electron Device Lett, 2023, 44(2): 221 doi: 10.1109/LED.2022.3229222
[15]
Lu X, Zhang X, Jiang H X, et al. Vertical β-Ga2O3 Schottky barrier diodes with enhanced breakdown voltage and high switching performance. Phys Status Solidi A, 2020, 217(3): 1900497 doi: 10.1002/pssa.201900497
[16]
Wu F H, Han Z, Liu J Y, et al. 8.7 A/700 V β-Ga2O3 Schottky barrier diode demonstrated by oxygen annealing combined with self-aligned mesa termination. Appl Phys Express, 2024, 17(3): 036504 doi: 10.35848/1882-0786/ad2d73
[17]
Xu X R, Deng Y C, Li T T, et al. Over 2 GW/cm2 low-conduction loss Ga2O3 vertical SBD with self-aligned field plate and mesa termination. Appl Phys Lett, 2024, 125(2): 022106 doi: 10.1063/5.0212785
[18]
Alfieri G, Mihaila A, Godignon P, et al. Deep level study of chlorine-based dry etched β-Ga2O3. J Appl Phys, 2021, 130(2): 025701 doi: 10.1063/5.0050416
[19]
Zhang Y H, Mei Z X, Wang T, et al. Flexible transparent high-voltage diodes for energy management in wearable electronics. Nano Energy, 2017, 40: 289 doi: 10.1016/j.nanoen.2017.08.025
[20]
Martínez-Angeles W L, González-Reynoso O, Carbajal-Arizaga G G, et al. Electronic barriers behavioral analysis of a Schottky diode structure featuring two-dimensional MoS2. Electronics, 2024, 13(20): 4008 doi: 10.3390/electronics13204008
[21]
Feng Y T, Zhou H, Ma J Y, et al. 120 A/1.78 kV p-Cr2O3/n-β-Ga2O3 heterojunction PN diodes with slanted mesa edge termination. IEEE Electron Device Lett, 2025, 46(10): 1705 doi: 10.1109/LED.2025.3598936
[22]
Zhao X X, Zhang S M, Shao G Q, et al. Over 450 V breakdown voltage in diamond vertical Schottky barrier diodes with anodic self-aligned mesa termination. Appl Phys Lett, 2025, 127(3): 032107 doi: 10.1063/5.0274905
[23]
Yang J C, Ren F, Khanna R, et al. Annealing of dry etch damage in metallized and bare (-201) Ga2O3. J Vac Sci Technol B, 2017, 35(5): 051201 doi: 10.1116/1.4986300
[24]
Sun Y, Kang X W, Zheng Y K, et al. Review of the recent progress on GaN-based vertical power Schottky barrier diodes (SBDs). Electronics, 2019, 8(5): 575 doi: 10.3390/electronics8050575
[25]
Dhara S, Kalarickal N K, Dheenan A, et al. β-Ga2O3 Schottky barrier diodes with 4.1 MV/cm field strength by deep plasma etching field-termination. Appl Phys Lett, 2022, 121(20): 203501 doi: 10.1063/5.0123284
[26]
Eifert B, Becker M, Reindl C T, et al. Raman studies of the intermediate tin-oxide phase. Phys Rev Mater, 2017, 1: 014602 doi: 10.1103/PhysRevMaterials.1.014602
[27]
Hudgins J L, Simin G S, Santi E, et al. An assessment of wide bandgap semiconductors for power devices. IEEE Trans Power Electron, 2003, 18(3): 907 doi: 10.1109/TPEL.2003.810840
[28]
Zhang L H, Verma A, Xing H G, et al. Inductively-coupled-plasma reactive ion etching of single-crystal β-Ga2O3. Jpn J Appl Phys, 2017, 56(3): 030304 doi: 10.7567/JJAP.56.030304
[29]
Wei S B, Hong Z F, Li C C, et al. Increase fixed charge at Al2O3/Ga2O3 interface for high-performance Ga2O3 trench Schottky barrier diodes by atomic nitrogen treatment. Appl Phys Lett, 2025, 126(15): 152108 doi: 10.1063/5.0254888
[30]
Zhong L H, Feng X, Zhang W H, et al. 2kV β-Ga2O3 Schottky diode with HfO2/SiO2 dual-layer field plate and mesa termination. Appl Phys Lett, 2025, 127(18): 182108 doi: 10.1063/5.0287147
[31]
Zhou F, Gong H H, Wang Z P, et al. Over 1.8 GW/cm2 beveled-mesa NiO/β-Ga2O3 heterojunction diode with 800 V/10 A nanosecond switching capability. Appl Phys Lett, 2025, 119(26): 262103 doi: 10.1063/5.0071280
[32]
Wu F H, Wen J P, Liu J Y, et al. Reliability of 1.5 × 1.5 mm2 β-Ga2O3 power diodes and application in DC–DC converter. Phys Status Solidi B, 2025, 262(8): 2400438
[33]
Xie S W, Alam M T, Gong J R, et al. 0.86 kV p-Si/(001)-Ga2O3 heterojunction diode. IEEE Electron Device Lett, 2024, 45(3): 444 doi: 10.1109/LED.2024.3352515
[34]
Xie S W, Sheikhi M, Xu S N, et al. P-GaAs/n-Ga2O3 heterojunction diode with breakdown voltage of ~800 V. Appl Phys Lett, 2024, 124(7): 073503 doi: 10.1063/5.0181056
[35]
Callahan W A, Egbo K, Lee C W, et al. Reliable operation of Cr2O3: Mg/β-Ga2O3 p–n heterojunction diodes at 600 °C. Appl Phys Lett, 2024, 124(15): 153504 doi: 10.1063/5.0185566

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    Received: 27 February 2026 Revised: 13 April 2026 Online: Accepted Manuscript: 18 May 2026

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      Article Navigation >  Journal of Semiconductors  > 2026  > Accepted Manuscript
      Xinwang Yao, Lizhi Cui, Junwei Zhang, Junhan Qian, Xiaoping Yang, Xiujuan Wang, Chunyan Wu, Linbao Luo. Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/26020066 ****X W Yao, L Z Cui, J W Zhang, J H Qian, X P Yang, X J Wang, C Y Wu, and L B Luo, Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/26020066
      Citation:
      Xinwang Yao, Lizhi Cui, Junwei Zhang, Junhan Qian, Xiaoping Yang, Xiujuan Wang, Chunyan Wu, Linbao Luo. Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/26020066 ****
      X W Yao, L Z Cui, J W Zhang, J H Qian, X P Yang, X J Wang, C Y Wu, and L B Luo, Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/26020066
      shu

      Self-aligned SnO/β-Ga2O3 mesa heterojunction diodes with a PFOM of 0.93 GW/cm2

      DOI: 10.1088/1674-4926/26020066
      CSTR: 32376.14.1674-4926.26020066

      • Institute of Microelectronics, Hefei University of Technology, Hefei 230009, China

      More Information
      • Xinwang Yao received his bachelor's degree from Hubei University in 2019. Currently, he is a master’s student at Hefei University of Technology under the supervision of Prof. Chunyan Wu. His research focuses on power diode devices based on β-Ga2O3
      • Chunyan Wu received her Ph.D. degree in inorganic chemistry from the University of Science and Technology of China in 2006. She is currently a professor at the School of Microlectronics, Hefei University of Technology, China. Her research interest mainly focuses on high-performance optoelectronic and electronic device applications, including photodetectors, optoelectronic synaptic devices and power devices
      • Corresponding author: cywu@hfut.edu.cn
      • Received Date: 2026-02-27
      • Revised Date: 2026-04-13
        • Available Online: 2026-05-18

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