Polarization-enhanced GaN Schottky barrier diodes: Ultra-thin InGaN for high breakdown voltage and low Ron

In this work, we present a concept that leverages the strong piezoelectric polarization field in InGaN, which counteracts the external electric field at reverse bias. We show that despite the smaller InGaN band-gap and lower critical electric field, its strong polarization field can reduce leakage current and enhance the breakdown voltage of GaN vertical devices. By introducing a few-nm-thick p-InGaN layer between the Schottky contact and the drift region in vertical GaN Schottky barrier diodes (SBDs), a drastic reduction in leakage current could be achieved without degradation in specific on-resistance (RON,sp). Our fabricated GaN SBDs with p-InGaN layer exhibited a high breakdown voltage of 800 V and a remarkably low RON,sp of 0.48 mΩcm2, leading to a Baliga’s figure of merit of 1.32 GW/cm2, one of the highest ever reported for GaN SBDs. This work demonstrates the capabilities of polarization engineering to achieve high-performance III-nitride devices.