Electric Field Management and Sidewall Leakage Current Suppression of RESURF-mesa for High-Performance Ga<sub>2</sub>O<sub>3</sub> Power Devices
Jiangbin Wan, Hengyu Wang, Haoyuan Cheng, Ce Wang, Chi Zhang, Kuang Sheng
Abstract
This work demonstrates high-performance vertical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\beta}$</tex-math></inline-formula>-Ga<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{2}}$</tex-math></inline-formula>O<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{3}}$</tex-math></inline-formula> rectifiers featuring a reduced-surface-field mesa (RESURF-mesa) structure. This RESURF-mesa design employs nonself-aligned etching to form a 5-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\mu}$</tex-math></inline-formula>m deep mesa, utilizing a 5-μm-thick SiO<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{2}}$</tex-math></inline-formula> layer and 120-nm p-type nickel oxide (NiO) to encapsulate the sidewalls with an argon-to-oxygen flux ratio of 20:1. Technology computer-aided design (TCAD) simulations confirm a reduced surface electric field (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i>-field) with an optimized NiO thickness. Consequently, the RESURF-mesa Schottky barrier diode (SBD) with 120-nm NiO exhibits a breakdown voltage (BV) of 2600 V, while the RESURF-mesa heterojunction diode (HJD) sustains a reverse voltage exceeding 3000 V due to the stronger heterointerface. The specific ON-resistance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\mathit{\textit{R}}}\boldsymbol{_{\textit{ON},\textit{sp}}}$</tex-math></inline-formula>) of both devices is 4.1 m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\Omega}\cdot$</tex-math></inline-formula>cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{^\text{2}}$</tex-math></inline-formula>, yielding the power figure of merit (PFOM) of 1.6 GW/cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{^\text{2}}$</tex-math></inline-formula> for RESURF-mesa SBD and 2.2 GW/cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{^\text{2}}$</tex-math></inline-formula> for RESURF-mesa HJD. The performance of both rectifiers is among the highest in reported multikilovolts Ga<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{2}}$</tex-math></inline-formula>O<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{3}}$</tex-math></inline-formula> SBDs and HJDs. Additionally, we have investigated the origin of sidewall leakage current and developed methods to suppress it, which is also effective at high temperatures. These findings underscore the significant potential of RESURF-mesa technology in advancing multikilovolt Ga<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{2}}$</tex-math></inline-formula>O<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\text{3}}$</tex-math></inline-formula> device applications.