High Voltage (~2 kV) field-plated Al0.64Ga0.36N-channel HEMTs

TL;DR

This paper reports on the fabrication and characterization of high-voltage AlGaN-channel HEMTs with a focus on breakdown voltage, on-resistance, and the effects of surface passivation and field plates.

Contribution

It introduces high-voltage AlGaN HEMTs with detailed analysis of breakdown voltage, passivation effects, and the relationship between breakdown voltage and on-resistance.

Findings

Breakdown voltage exceeded 3 kV before passivation, reduced to ~2 kV after SiN passivation.

On-resistance was approximately 75 ohm·mm, with a linear correlation to breakdown voltage.

Dynamic RON increased by ~5% in pulsed measurements, with less than 10% current collapse.

Abstract

High voltage (~2 kV) AlGaN-channel HEMTs were fabricated with 64% Aluminum composition in the channel. The average on-resistance was ~75 ohm. mm (~21 miliohm. cm^2) for LGD = 20 microns. Breakdown voltage reached >3 kV (tool limit) before passivation however it reduced to ~2 kV after SiN surface passivation and field plates. The apparent high breakdown voltage prior to passivation can possibly be attributed to the field plate effect of the charged trap states of the surface. The breakdown voltage and RON demonstrated a strong linear correlation in a scattered plot with ~50 measured transistors. In pulsed IV measurements with 100 microsecond pulse width and 40 V of off-state bias (tool limit), the dynamic RON increased by ~5% compared to DC RON and current collapse was <10%.