Threshold Voltage Instability in GaN HEMTs With p-Type Gate: Mg Doping Compensation

In this letter, we present an analysis of the threshold voltage shift induced by positive bias temperature instability stress in GaN-based power HEMTs with p-type gate, controlled by a Schottky metal/p-GaN junction. In particular, we show the positive effect of the magnesium compensation process in the p-GaN layer on the long-term threshold voltage instability. When a relatively high positive bias is applied to the gate (Schottky junction reverse-biased), holes are generated by impact ionization in the high-field depleted p-GaN region, then accelerated toward the AlGaN layer. The high-energy holes, combined with the high temperature effects, create defects in the AlGaN or at its interface with p-GaN, causing a long-term positive threshold voltage shift. A process variation in the p-GaN layer is introduced which promotes a wider depletion region near the Schottky interface with the metal, lowering the electric field and reducing the generation of holes due to impact ionization. As a result, the long-term threshold voltage instability is improved without altering the dc transistor parameters, such as threshold voltage, trans-conductance, and subthreshold slope.

[1]  H. A. Moghadam,et al.  Mechanism of Threshold Voltage Shift in ${p}$ -GaN Gate AlGaN/GaN Transistors , 2018, IEEE Electron Device Letters.

[2]  Gaudenzio Meneghesso,et al.  Field- and current-driven degradation of GaN-based power HEMTs with p-GaN gate: Dependence on Mg-doping level , 2017, Microelectron. Reliab..

[3]  Giuseppe Iannaccone,et al.  Charge Injection in Normally-Off p-GaN Gate AlGaN/GaN-on-Si HFETs , 2018, 2018 48th European Solid-State Device Research Conference (ESSDERC).

[4]  M. Meneghini,et al.  Reliability and failure analysis in power GaN-HEMTs: An overview , 2017, 2017 IEEE International Reliability Physics Symposium (IRPS).

[5]  Eldad Bahat Treidel,et al.  Gate Reliability Investigation in Normally-Off p-Type-GaN Cap/AlGaN/GaN HEMTs Under Forward Bias Stress , 2016, IEEE Electron Device Letters.

[6]  Eldad Bahat Treidel,et al.  Experimental demonstration of weibull distributed failure in p-type GaN high electron mobility transistors under high forward bias stress , 2016, International Symposium on Power Semiconductor Devices and IC's.

[7]  S. Decoutere,et al.  200mm GaN-on-Si epitaxy and e-mode device technology , 2015, 2015 IEEE International Electron Devices Meeting (IEDM).

[8]  Philippe Godignon,et al.  A Survey of Wide Bandgap Power Semiconductor Devices , 2014, IEEE Transactions on Power Electronics.

[9]  U. Chung,et al.  p-GaN Gate HEMTs With Tungsten Gate Metal for High Threshold Voltage and Low Gate Current , 2013, IEEE Electron Device Letters.

[10]  Qi Zhou,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, 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD).

[11]  Alex Q. Huang,et al.  The 2018 GaN power electronics roadmap , 2018, Journal of Physics D: Applied Physics.

[12]  G. Longobardi,et al.  On the physical operation and optimization of the p-GaN gate in normally-off GaN HEMT devices , 2017 .

[13]  S. Decoutere,et al.  Impact of Mg out-diffusion and activation on the p-GaN gate HEMT device performance , 2016, 2016 28th International Symposium on Power Semiconductor Devices and ICs (ISPSD).

[14]  Enrico Sangiorgi,et al.  PBTI in GaN-HEMTs With p-Type Gate: Role of the Aluminum Content on $\Delta V_{\mathrm {TH}}$ and Underlying Degradation Mechanisms , 2018, IEEE Transactions on Electron Devices.

[15]  Enrico Sangiorgi,et al.  Investigation of the p-GaN Gate Breakdown in Forward-Biased GaN-Based Power HEMTs , 2017, IEEE Electron Device Letters.

[16]  Gaudenzio Meneghesso,et al.  Time-Dependent Failure of GaN-on-Si Power HEMTs With p-GaN Gate , 2016, IEEE Transactions on Electron Devices.

[17]  Jian-jang Huang,et al.  Impact of Gate Metal on the Performance of p-GaN/AlGaN/GaN High Electron Mobility Transistors , 2015, IEEE Electron Device Letters.

[18]  S. Decoutere,et al.  Failure mode for p-GaN gates under forward gate stress with varying Mg concentration , 2017, 2017 IEEE International Reliability Physics Symposium (IRPS).

[19]  Gaudenzio Meneghesso,et al.  Impact of Sidewall Etching on the Dynamic Performance of GaN-on-Si E-Mode Transistors , 2018, 2019 IEEE International Reliability Physics Symposium (IRPS).

[20]  Alex Lidow,et al.  GaN-on-Si Power Technology: Devices and Applications , 2017, IEEE Transactions on Electron Devices.

[21]  Niels Posthuma,et al.  Analytical Model for the Threshold Voltage of ${p}$ -(Al)GaN High-Electron-Mobility Transistors , 2018, IEEE Transactions on Electron Devices.

[22]  Giuseppe Iannaccone,et al.  Threshold Voltage Instability in p-GaN Gate AlGaN/GaN HFETs , 2018, IEEE Transactions on Electron Devices.

[23]  G. Meneghesso,et al.  Degradation Mechanisms of GaN HEMTs With p-Type Gate Under Forward Gate Bias Overstress , 2018, IEEE Transactions on Electron Devices.

[24]  S. Decoutere,et al.  Degradation of GaN-HEMTs with p-GaN Gate: Dependence on temperature and on geometry , 2017, 2017 IEEE International Reliability Physics Symposium (IRPS).

[25]  S. Decoutere,et al.  An industry-ready 200 mm p-GaN E-mode GaN-on-Si power technology , 2018, 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD).

[26]  Kevin J. Chen,et al.  VTH Instability of ${p}$ -GaN Gate HEMTs Under Static and Dynamic Gate Stress , 2018, IEEE Electron Device Letters.