A Comparative Study on G-to-S ESD Robustness of the Ohmic-Gate and Schottky-Gate p-GaN HEMTs
Yijun Shi, Zhiyuan He, Yun Huang, Zongqi Cai, Yiqiang Chen, Liye Cheng, Wanjun Chen, Ruize Sun, Chao Liu, Guoguang Lu, Bo Zhang
Abstract
In this work, we have comprehensively studied the forward/reverse G-to-S electrostatic discharge (ESD) robustness for Ohmic-gate p-GaN HEMT. It is found that Ohmic-gate p-GaN HEMT exhibits superior G-to-S ESD robustness than Schottky-gate p-GaN HEMT with similar current capacity. First, Ohmic-gate p-GaN HEMT possesses a high forward/reverse second breakdown current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {SF}}/I_{\text {SR}}$ </tex-math></inline-formula> ) of 9.3/2.7 A, while the value is 2.0/0.1 A for Schottky-gate p-GaN HEMT. Correspondingly, the equivalent forward/reverse human body model (HBM) failure voltages ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {HBM-F}}/{V}_{\text {HBM-R}} = {1500} \Omega \times {I}_{\text {SF}}/{I}_{\text {SR}}$ </tex-math></inline-formula> ) are 14/4.05 kV and 3/0.15 kV for Ohmic-gate and Schottky-gate p-GaN HEMTs, respectively. In addition, Schottky-gate p-GaN HEMT exhibits obvious changes in its ON-state current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {I}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> = 0.8/0.7 A), threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {V}_{\text {TH}}$ </tex-math></inline-formula> = 0.23/0.35 V), G-to-S leakage after the forward/reverse repetitive G-to-S ESD stress. While there is no obvious change ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {I}_{ \mathrm{ON}}$ </tex-math></inline-formula> = 0 A and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {V}_{\text {TH}}$ </tex-math></inline-formula> = 0 V) in Ohmic-gate p-GaN HEMT, which may be attributed to that there are numerous holes to recombine the electrons trapped at the recombination center. But for Schottky-gate p-GaN HEMT, there is no enough holes to recombine the electrons trapped at the recombination center, due to the Schottky barrier at gate region.