Wide Bandgap Vertical kV-Class <i>β</i>-Ga₂O₃/GaN Heterojunction p-n Power Diodes With Mesa Edge Termination
Dinusha Herath Mudiyanselage, Dawei Wang, Houqiang Fu
Abstract
Breakdown capability of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\beta }$ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /GaN heterojunction-based vertical p-n power diodes with mesa edge termination (ET) was comprehensively investigated using TCAD simulation. With <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~{\mu }\text{m}~{\beta }$ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> drift layer, the ideal breakdown voltage (BV) of the heterojunction was 1.37 kV, while the BV of the reference device without effective mesa edge termination decreased dramatically to 300 V due to the electric field crowding at the device edge. Four mesa ET structures were investigated to mitigate the electric field crowding at the junction edge, including beveled mesa, step mesa, deeply etched mesa, and p-doped guard ring. Without effective ET, the peak electric field at the junction edge was ~4.2 MV/cm at −300 V. By incorporating these ET techniques, the peak electric fields were reduced significantly to 0.73 MV/cm. Ideal BV of 1.37 kV was achievable using deeply etched mesa and guard ring ETs. The beveled mesa realized >80% of the ideal BV, while step mesa ET was less effective in alleviating the electric field crowding and only offered ~ 40% of the ideal BV. The device BV can be further scaled by varying <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> drift layer thickness. This work can serve as an important reference and guideline for developing high power high voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> based bipolar power devices.