Simulation of Enhancement Mode GaN HEMTs with Threshold > 5 V using P-type Buffer

TL;DR

This paper presents the simulation of a high-threshold enhancement-mode GaN HEMT with a p-type buffer, demonstrating tunable threshold voltages above 5 V and analyzing its electrical performance and tradeoffs.

Contribution

It introduces a novel p-type buffer design for GaN HEMTs, enabling threshold voltage tunability over an unprecedented range and providing analytical insights into device behavior.

Findings

Threshold voltage exceeds 5 V in simulations.

Reducing oxide capacitance shifts threshold voltage positively.

Device shows promising breakdown and on-resistance characteristics.

Abstract

A high threshold voltage enhancement-mode GaN HEMT with p-type doped buffer is discussed and simulated. Analytical expressions are derived to explain the role of buffer capacitance in designing and enhancing threshold voltage. Simulations of the proposed device with p-type buffer show threshold voltages above 5 V, and a positive shift in threshold voltage as the oxide capacitance is reduced, thus enabling threshold voltage tunability over an unprecedented range for GaN-based HEMTs. The electric field profiles, breakdown performance, on-resistance and delay tradeoffs in the proposed pGaN back HEMT device are also discussed.