Suppressing Buffer-Induced Current Collapse in GaN HEMTs with a Source-Connected p-GaN (SCPG): A Simulation Study

Wei Lin,Bing Xie,Maojun Wang,Yilong Hao,Haozhe Sun,Bo Shen,Cheng P Wen

doi:10.3390/electronics10080942

Wei Lin, Bing Xie + Show 5 more

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https://doi.org/10.3390/electronics10080942

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Journal: Electronics	Publication Date: Apr 15, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Peking University, Institute of Microelectronics

Abstract

Carbon doping in the buffer of AlGaN/GaN high-electron-mobility transistors (HEMTs) leads to the notorious current collapse phenomenon. In this paper, an HEMT structure with a source-connected p-GaN (SCPG) embedded in the carbon-doped semi-insulating buffer is proposed to suppress the buffer-induced current collapse effect. Two-dimensional transient simulation was carried out to show the successful suppression of buffer-induced current collapse in the SCPG-HEMTs compared with conventional HEMTs. The mechanism of suppressing dynamic on-resistance degradation by ejecting holes from the SCPG into the high resistive buffer layer after off-state stress is illustrated based on energy band diagrams. This paper contributes an innovative device structure to potentially solve the buffer-induced degradation of the dynamic on-resistance in GaN power devices.

Highlights

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) on silicon substrate are excellent candidates for next-generation high-voltage power electronics [1,2,3,4]
A semi-insulating GaN buffer layer is required before the growth of the AlGaN/GaN heterostructure to avoid unwanted parallel current paths and ensure excellent pinch-off characteristics
The buffer layers are commonly realized by carbon-doped GaN, obtained by controlling the growth pressure, V/III ratio, and growth temperature [8], or adding an external carbon source [9] during MOCVD growth

Summary

Introduction

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) on silicon substrate are excellent candidates for next-generation high-voltage power electronics [1,2,3,4]. Polarization effects in AlGaN/GaN heterostructures introduce high-density and high-mobility two-dimensional electron gas (2DEG) [5,6,7], which lowers on-state resistance (Ron) and energy waste in power switches. A semi-insulating GaN buffer layer is required before the growth of the AlGaN/GaN heterostructure to avoid unwanted parallel current paths and ensure excellent pinch-off characteristics. Introducing carbon into the buffer exacerbates the notorious current collapse (CC) or named dynamic on-resistance degradation phenomenon in GaN HEMTs [10,11]

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Discussion

Conclusion