Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts

Liying Ding; Xulei Qin; Guohao Yu; Jiaan Zhou; Yu Li; Chunfeng Hao; Huixin Yue; Yuxiang Zhang; Jinxia Jiang; Jiawei Ye; Zhongming Zeng; Baoshun Zhang

doi:10.1088/1674-4926/25090027

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Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts

Liying Ding^{1, 2}, Xulei Qin^1,, Guohao Yu^2,, Jiaan Zhou², Yu Li², Chunfeng Hao², Huixin Yue², Yuxiang Zhang², Jinxia Jiang², Jiawei Ye², Zhongming Zeng² and Baoshun Zhang²

+ Author Affiliations

1. School of Physics, Changchun University of Science and Technology, Changchun 130013, China
2. Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-Bionics, CAS, Suzhou 215123, People's Republic of China

Author Bio:

Liying Ding received her BS degree from Jilin Normal University in 2022.She is now an MS student at Changchun University of Science and Technology. Her research focuses on GaN vertical power devices and their reliability.

Xulei Qin received his PhD degree from Changchun University of Science and Technology in 2015. Currently, he is an associate professor at Changchun University of Science and Technology. His main research interests include optoelectronic thin film materials and imaging devices.

Guohao Yu received his Ph.D. in Microelectronics and Solid-State Electronics from the Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences in 2013. He then conducted postdoctoral research at SINANO and currently serves as a Senior Engineer at the institute. His research interests focus on GaN power electronic devices and GaN power conversion modules.

Baoshun Zhang received his BS degree from Changchun University of Science and Technology in 1994 and his PhD degree from the Institute of Semiconductors, Chinese Academy of Sciences in 2003. Then he joined in Hong Kong University of Science and Technology. Currently, he is a researcher at Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, and his research interests include semiconductor material growth and device technology research.

Corresponding author: Xulei Qin, qxl@cust.edu.cn; Guohao Yu, ghyu2009@sinano.ac.cn

DOI: 10.1088/1674-4926/25090027CSTR: 32376.14.1674-4926.25090027

Abstract: This work demonstrates a high-performance vertical GaN p-i-n diode based on a buried p-layer n-p-i-n epitaxial structure. The post-etch magnesium (Mg) diffusion process is applied to suppress the etch-induced surface damage on the p-GaN layer. The Mg diffusion effectively reduces the valence band barrier from 2 eV to 1.1 eV, yielding a low specific contact resistivity of 6.521 × 10⁻⁴ Ω·cm². As a result, the fabricated devices exhibit markedly enhanced forward characteristics, including a reduced turn-on voltage of 3.3 V and a specific on-resistance of 0.92 mΩ·cm2. Temperature-dependent forward I-V measurements indicate that the dominant carrier transport mechanism evolves from defect-related tunneling in the etched devices toward transport dominated by intrinsic p–n junction conduction after Mg diffusion. In addition, the devices exhibit excellent stability in forward conduction, with a voltage variation of approximately 0.028 V. These results indicate that Mg diffusion effectively improves the contact characteristics degraded by ICP etching and provide a viable approach for achieving high-performance and reliable vertical GaN power devices.

Key words: GaN, vertical power devices, Sapphire substrate, magnesium, Ohmic contacts, p-i-n diodes.

References

[1]	Amano H, Kito M, Hiramatsu K, et al. P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI). Jpn J Appl Phys, 1989, 28(12A): L2112 doi: 10.1143/JJAP.28.L2112
[2]	Lu S, Deki M, Wang J, et al. Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg. Appl Phys Lett, 2021, 119(24): 242104 doi: 10.1063/5.0076764
[3]	Li D S, Sumiya M, Fuke S, et al. Selective etching of GaN polar surface in potassium hydroxide solution studied by X-ray photoelectron spectroscopy. J Appl Phys, 2001, 90(8): 4219 doi: 10.1063/1.1402966
[4]	Cao X A, Pearton S J, Zhang A P, et al. Electrical effects of plasma damage in p-GaN. Appl Phys Lett, 1999, 75(17): 2569 doi: 10.1063/1.125080
[5]	Wang J, Lu S, Cai W T, et al. Ohmic contact to p-type GaN enabled by post-growth diffusion of magnesium. IEEE Electron Device Lett, 2022, 43(1): 150 doi: 10.1109/LED.2021.3131057
[6]	Li W S, Nomoto K, Lee K, et al. Development of GaN vertical trench-MOSFET with MBE regrown channel. IEEE Trans Electron Devices, 2018, 65(6): 2558 doi: 10.1109/TED.2018.2829125
[7]	Zhang L, Wang X Y, Zeng J P, et al. AlGaN/GaN heterojunction bipolar transistors with high current gain and low specific on-resistance. IEEE Trans Electron Devices, 2022, 69(12): 6633 doi: 10.1109/TED.2022.3217245
[8]	Chowdhury N, Lemettinen J, Xie Q Y, et al. P-channel GaN transistor based on p-GaN/AlGaN/GaN on Si. IEEE Electron Device Lett, 2019, 40(7): 1036 doi: 10.1109/LED.2019.2916253
[9]	Tang C Y, Fu C, Jiang Y, et al. Carrier transport mechanism of Mg/Pt/Au Ohmic contact on p-GaN/AlGaN/GaN platform with ultra-low resistivity. Appl Phys Lett, 2023, 123(9): 092104 doi: 10.1063/5.0154841
[10]	Zheng Z Y, Zhang L, Song W J, et al. Gallium nitride-based complementary logic integrated circuits. Nat Electron, 2021, 4(8): 595 doi: 10.1038/s41928-021-00611-y
[11]	Hahn H, Reuters B, Kotzea S, et al. First monolithic integration of GaN-based enhancement mode n-channel and p-channel heterostructure field effect transistors. 72nd Device Research Conference. Santa Barbara, CA, USA. IEEE, 2014: 259
[12]	He J L, Zhong Y Z, Zhou Y, et al. Recovery of p-GaN surface damage induced by dry etching for the formation of p-type Ohmic contact. Appl Phys Express, 2019, 12(5): 055507 doi: 10.7567/1882-0786/ab13d7
[13]	Jang H W, Lee J L. Effect of Cl2 plasma treatment on metal contacts to n-type and p-type GaN. J Electrochem Soc, 2003, 150(9): G513 doi: 10.1149/1.1595664
[14]	Fang Z Q, Look D C, Wang X L, et al. Plasma-etching-enhanced deep centers in n-GaN grown by metalorganic chemical-vapor deposition. Appl Phys Lett, 2003, 82(10): 1562 doi: 10.1063/1.1560562
[15]	Kumabe T, Ando Y, Watanabe H, et al. Etching-induced damage in heavily Mg-doped p-type GaN and its suppression by low-bias-power inductively coupled plasma-reactive ion etching. Jpn J Appl Phys, 2021, 60: SBBD03 doi: 10.35848/1347-4065/abd538
[16]	Foster G M, Koehler A, Ebrish M, et al. Recovery from plasma etching-induced nitrogen vacancies in p-type gallium nitride using UV/O3 treatments. Appl Phys Lett, 2020, 117(8): 082103 doi: 10.1063/5.0021153
[17]	Huang S, Wang X, Yao Y, et al. Threshold voltage instability in III-nitride heterostructure metal-insulator-semiconductor high-electron-mobility transistors: Characterization and interface engineering. Appl Phys Rev, 2024, 11(2): 021325 doi: 10.1063/5.0179376
[18]	Abdul Khadar R, Liu C, Zhang L Y, et al. 820-V GaN-on-Si quasi-vertical p-i-n diodes with BFOM of 2.0 GW/Cm2. IEEE Electron Device Lett, 2018, 39(3): 401 doi: 10.1109/LED.2018.2793669
[19]	Auf der Maur M, Galler B, Pietzonka I, et al. Trap-assisted tunneling in InGaN/GaN single-quantum-well light-emitting diodes. Appl Phys Lett, 2014, 105(13): 133504 doi: 10.1063/1.4896970
[20]	Kozodoy P, Ibbetson J P, Marchand H, et al. Electrical characterization of GaN p-n junctions with and without threading dislocations. Appl Phys Lett, 1998, 73(7): 975 doi: 10.1063/1.122057
[21]	He J B, Tang G F, Chen K J. VTH instability of ${p}$-GaN gate HEMTs under static and dynamic gate stress. IEEE Electron Device Lett, 2018, 39(10): 1576 doi: 10.1109/led.2018.2867938
[22]	Shi Y Y, Zhou Q, Cheng Q, et al. Bidirectional threshold voltage shift and gate leakage in 650 V p-GaN AlGaN/GaN HEMTs: The role of electron-trapping and hole-injection. 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD). Chicago, IL, USA. IEEE, 2018: 96
[23]	Tallarico A N, Stoffels S, Posthuma N, et al. PBTI in GaN-HEMTs with p-type gate: Role of the aluminum content on $\Delta V\mathrm{TH}$ and underlying degradation mechanisms. IEEE Trans Electron Devices, 2018, 65(1): 38 doi: 10.1109/TED.2017.2769167

Fig. 1. (Color online) (a) Epitaxial structures for device fabrication. (b)-(e) Schematic diagram of key steps in the plasma and Mg treatment process for p-i-n diodes. (f) Structural schematic of p-i-n diode. (g) Schematic diagram of the CTLM structure.

DownLoad: Full-Size Img PowerPoint

Fig. 2. (Color online) (a) Comparison of current-voltage characteristics for ICP-etched p-GaN contacts with and without Mg diffusion. (b) Current-voltage characteristics of Mg-diffused samples versus annealing temperature. All measurements were performed on CTLM patterns with a 2 µm gap spacing.

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Color online) (a) XPS valence band spectra of the contact interface for the sample without Mg treatment and (b) the sample with Mg treatment. (c) Schematic diagram of the valence band maximum shift determined by XPS measurements. (d) SIMS-measured longitudinal distribution of Mg element.

DownLoad: Full-Size Img PowerPoint

Fig. 4. (Color online) Electrical characteristics of p-i-n diodes with and without Mg diffusion. (a) Forward I-V characteristics (linear scale). (b) Forward I-V characteristics (log scale). (c) Reverse I-V characteristics.

DownLoad: Full-Size Img PowerPoint

Fig. 5. (Color online) (a) Temperature-dependent forward J-V characteristics for the sample without Mg treatment and (b) the sample with Mg treatment. The insets show the Arrhenius plots of ln(I₀) versus 1/kT, used to estimate the activation energy.

DownLoad: Full-Size Img PowerPoint

Fig. 6. (Color online) I-V characteristics of quasi-vertical p-i-n diodes under forward-bias stress (+3.5 V) and the impact of on-state stress. (a) Forward I-V characteristic for the device with Mg diffusion. (b) Forward I-V characteristic for the device without Mg diffusion. (c) Comparison of forward voltage shift during on-state stress for both devices.

DownLoad: Full-Size Img PowerPoint

[1]	Amano H, Kito M, Hiramatsu K, et al. P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI). Jpn J Appl Phys, 1989, 28(12A): L2112 doi: 10.1143/JJAP.28.L2112
[2]	Lu S, Deki M, Wang J, et al. Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg. Appl Phys Lett, 2021, 119(24): 242104 doi: 10.1063/5.0076764
[3]	Li D S, Sumiya M, Fuke S, et al. Selective etching of GaN polar surface in potassium hydroxide solution studied by X-ray photoelectron spectroscopy. J Appl Phys, 2001, 90(8): 4219 doi: 10.1063/1.1402966
[4]	Cao X A, Pearton S J, Zhang A P, et al. Electrical effects of plasma damage in p-GaN. Appl Phys Lett, 1999, 75(17): 2569 doi: 10.1063/1.125080
[5]	Wang J, Lu S, Cai W T, et al. Ohmic contact to p-type GaN enabled by post-growth diffusion of magnesium. IEEE Electron Device Lett, 2022, 43(1): 150 doi: 10.1109/LED.2021.3131057
[6]	Li W S, Nomoto K, Lee K, et al. Development of GaN vertical trench-MOSFET with MBE regrown channel. IEEE Trans Electron Devices, 2018, 65(6): 2558 doi: 10.1109/TED.2018.2829125
[7]	Zhang L, Wang X Y, Zeng J P, et al. AlGaN/GaN heterojunction bipolar transistors with high current gain and low specific on-resistance. IEEE Trans Electron Devices, 2022, 69(12): 6633 doi: 10.1109/TED.2022.3217245
[8]	Chowdhury N, Lemettinen J, Xie Q Y, et al. P-channel GaN transistor based on p-GaN/AlGaN/GaN on Si. IEEE Electron Device Lett, 2019, 40(7): 1036 doi: 10.1109/LED.2019.2916253
[9]	Tang C Y, Fu C, Jiang Y, et al. Carrier transport mechanism of Mg/Pt/Au Ohmic contact on p-GaN/AlGaN/GaN platform with ultra-low resistivity. Appl Phys Lett, 2023, 123(9): 092104 doi: 10.1063/5.0154841
[10]	Zheng Z Y, Zhang L, Song W J, et al. Gallium nitride-based complementary logic integrated circuits. Nat Electron, 2021, 4(8): 595 doi: 10.1038/s41928-021-00611-y
[11]	Hahn H, Reuters B, Kotzea S, et al. First monolithic integration of GaN-based enhancement mode n-channel and p-channel heterostructure field effect transistors. 72nd Device Research Conference. Santa Barbara, CA, USA. IEEE, 2014: 259
[12]	He J L, Zhong Y Z, Zhou Y, et al. Recovery of p-GaN surface damage induced by dry etching for the formation of p-type Ohmic contact. Appl Phys Express, 2019, 12(5): 055507 doi: 10.7567/1882-0786/ab13d7
[13]	Jang H W, Lee J L. Effect of Cl2 plasma treatment on metal contacts to n-type and p-type GaN. J Electrochem Soc, 2003, 150(9): G513 doi: 10.1149/1.1595664
[14]	Fang Z Q, Look D C, Wang X L, et al. Plasma-etching-enhanced deep centers in n-GaN grown by metalorganic chemical-vapor deposition. Appl Phys Lett, 2003, 82(10): 1562 doi: 10.1063/1.1560562
[15]	Kumabe T, Ando Y, Watanabe H, et al. Etching-induced damage in heavily Mg-doped p-type GaN and its suppression by low-bias-power inductively coupled plasma-reactive ion etching. Jpn J Appl Phys, 2021, 60: SBBD03 doi: 10.35848/1347-4065/abd538
[16]	Foster G M, Koehler A, Ebrish M, et al. Recovery from plasma etching-induced nitrogen vacancies in p-type gallium nitride using UV/O3 treatments. Appl Phys Lett, 2020, 117(8): 082103 doi: 10.1063/5.0021153
[17]	Huang S, Wang X, Yao Y, et al. Threshold voltage instability in III-nitride heterostructure metal-insulator-semiconductor high-electron-mobility transistors: Characterization and interface engineering. Appl Phys Rev, 2024, 11(2): 021325 doi: 10.1063/5.0179376
[18]	Abdul Khadar R, Liu C, Zhang L Y, et al. 820-V GaN-on-Si quasi-vertical p-i-n diodes with BFOM of 2.0 GW/Cm2. IEEE Electron Device Lett, 2018, 39(3): 401 doi: 10.1109/LED.2018.2793669
[19]	Auf der Maur M, Galler B, Pietzonka I, et al. Trap-assisted tunneling in InGaN/GaN single-quantum-well light-emitting diodes. Appl Phys Lett, 2014, 105(13): 133504 doi: 10.1063/1.4896970
[20]	Kozodoy P, Ibbetson J P, Marchand H, et al. Electrical characterization of GaN p-n junctions with and without threading dislocations. Appl Phys Lett, 1998, 73(7): 975 doi: 10.1063/1.122057
[21]	He J B, Tang G F, Chen K J. VTH instability of ${p}$-GaN gate HEMTs under static and dynamic gate stress. IEEE Electron Device Lett, 2018, 39(10): 1576 doi: 10.1109/led.2018.2867938
[22]	Shi Y Y, Zhou Q, Cheng Q, et al. Bidirectional threshold voltage shift and gate leakage in 650 V p-GaN AlGaN/GaN HEMTs: The role of electron-trapping and hole-injection. 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD). Chicago, IL, USA. IEEE, 2018: 96
[23]	Tallarico A N, Stoffels S, Posthuma N, et al. PBTI in GaN-HEMTs with p-type gate: Role of the aluminum content on $\Delta V\mathrm{TH}$ and underlying degradation mechanisms. IEEE Trans Electron Devices, 2018, 65(1): 38 doi: 10.1109/TED.2017.2769167

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Received: 30 September 2025 Revised: 23 January 2026 Online: Accepted Manuscript: 15 March 2026

Article Navigation > Journal of Semiconductors > 2026 > Accepted Manuscript

Liying Ding, Xulei Qin, Guohao Yu, Jiaan Zhou, Yu Li, Chunfeng Hao, Huixin Yue, Yuxiang Zhang, Jinxia Jiang, Jiawei Ye, Zhongming Zeng, Baoshun Zhang. Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/25090027 ****L Y Ding, X L Qin, G H Yu, J A Zhou, Y Li, C F Hao, H X Yue, Y X Zhang, J X Jiang, J W Ye, Z M Zeng, and B S Zhang, Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/25090027

Citation:

L Y Ding, X L Qin, G H Yu, J A Zhou, Y Li, C F Hao, H X Yue, Y X Zhang, J X Jiang, J W Ye, Z M Zeng, and B S Zhang, Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/25090027

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Enhanced performance of etched p-GaN P-i-N diodes via Mg diffusion-enabled ohmic contacts

DOI: 10.1088/1674-4926/25090027

CSTR: 32376.14.1674-4926.25090027

1.
School of Physics, Changchun University of Science and Technology, Changchun 130013, China
2.
Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-Bionics, CAS, Suzhou 215123, People's Republic of China

More Information

Liying Ding received her BS degree from Jilin Normal University in 2022.She is now an MS student at Changchun University of Science and Technology. Her research focuses on GaN vertical power devices and their reliability
Xulei Qin received his PhD degree from Changchun University of Science and Technology in 2015. Currently, he is an associate professor at Changchun University of Science and Technology. His main research interests include optoelectronic thin film materials and imaging devices
Guohao Yu received his Ph.D. in Microelectronics and Solid-State Electronics from the Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences in 2013. He then conducted postdoctoral research at SINANO and currently serves as a Senior Engineer at the institute. His research interests focus on GaN power electronic devices and GaN power conversion modules
Baoshun Zhang received his BS degree from Changchun University of Science and Technology in 1994 and his PhD degree from the Institute of Semiconductors, Chinese Academy of Sciences in 2003. Then he joined in Hong Kong University of Science and Technology. Currently, he is a researcher at Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, and his research interests include semiconductor material growth and device technology research
Corresponding author: qxl@cust.edu.cn; ghyu2009@sinano.ac.cn
Received Date: 2025-09-30
Revised Date: 2026-01-23

Available Online: 2026-03-15

Abstract

Abstract

This work demonstrates a high-performance vertical GaN p-i-n diode based on a buried p-layer n-p-i-n epitaxial structure. The post-etch magnesium (Mg) diffusion process is applied to suppress the etch-induced surface damage on the p-GaN layer. The Mg diffusion effectively reduces the valence band barrier from 2 eV to 1.1 eV, yielding a low specific contact resistivity of 6.521 × 10⁻⁴ Ω·cm². As a result, the fabricated devices exhibit markedly enhanced forward characteristics, including a reduced turn-on voltage of 3.3 V and a specific on-resistance of 0.92 mΩ·cm2. Temperature-dependent forward I-V measurements indicate that the dominant carrier transport mechanism evolves from defect-related tunneling in the etched devices toward transport dominated by intrinsic p–n junction conduction after Mg diffusion. In addition, the devices exhibit excellent stability in forward conduction, with a voltage variation of approximately 0.028 V. These results indicate that Mg diffusion effectively improves the contact characteristics degraded by ICP etching and provide a viable approach for achieving high-performance and reliable vertical GaN power devices.
- GaN,
- vertical power devices,
- Sapphire substrate,
- magnesium,
- Ohmic contacts,
- p-i-n diodes.

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