Mitigating Plasma Etch-Induced Negative Charge Trapping in 2.7 kV β‑Ga2O3 (001) Trench Schottky Barrier Diodes Using H3PO4 Treatment

TL;DR

A new method using H3PO4 treatment improves the stability and performance of high-voltage gallium oxide diodes.

Contribution

H3PO4 treatment is shown to reduce interface charge trapping and enhance device reliability in β-Ga2O3 trench Schottky barrier diodes.

Findings

H3PO4 treatment reduced on-resistance degradation from 20% to 9% under stress.

[010]-oriented devices achieved 2.7 kV breakdown voltage with low on-resistance.

TCAD simulations confirmed reduced negative interface charge density with H3PO4.

Abstract

Stable β-Ga2O3 (001) trench
Schottky
barrier diodes (TSBDs) with a Baliga’s figure-of-merit (BFOM)
of 0.7 GW cm–2 were demonstrated by reducing the
Al2O3/Ga2O3 interface
state trap density using a H3PO4 surface treatment
during device fabrication. TSBDs with fins oriented along different
directions have been studied, wherein devices with [010] fin orientation
exhibited a low specific on-resistance (R
on,sp) of 11 mΩ cm2 and a breakdown voltage (V
br) of up to 2.7 kV with H3PO4 treatment. Reliability testing using sequential voltage stress
up to a reverse bias of −1.2 kV showed a degradation in R
on,sp by 20% in untreated devices but only by
9% in those with the H3PO4 surface treatment.
TCAD simulations confirm that the H3PO4 treatment
mitigates the density of negative interface charges, highlighting
the effectiveness of the acid treatment in controlling defect-mediated
instabilities. Furthermore, high-temperature bias stress tests demonstrated
that [010]-oriented TSBDs achieved superior thermal and electrical
stability after the treatment, eliminating the 10% R
on,sp increase observed in untreated devices. These results
establish H3PO4 surface treatment as an effective
strategy for enhancing the robustness of β-Ga2O3 power devices under combined thermal and electrical stress.

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