Electrostatic Engineering using Extreme Permittivity Materials for Ultra-wide Bandgap Semiconductor Transistors

Abstract

The performance of ultra-wide band gap materials like $\beta$-Ga${}_2$O${}_3$ is critically dependent on achieving high average electric fields within the active region of the device. In this report, we show that high-k gate dielectrics like BaTiO${}_3$ can provide an efficient field management strategy by improving the uniformity of electric field profile in the gate-drain region of lateral field effect transistors. Using this strategy, we were able to achieve high average breakdown fields of 1.5 MV/cm and 4 MV/cm at gate-drain spacing (L${}_{\mathrm{gd}}$) of 6 um and 0.6 um respectively in $\beta$-Ga${}_2$O${}_3$, at a high channel sheet charge density of 1.8x10${}^{13}$cm${}^{-2}$. The high sheet charge density together with high breakdown field enabled a record power figure of merit (V${}^2$${}_{\mathrm{br}}$/R${}_{\mathrm{on}}$) of 376 MW/cm${}^2$ at a gate-drain spacing of 3 um.