Development of gallium oxide power devices

TLDR

Gallium oxide (Ga₂O₃) offers a large bandgap of 4.7–4.9 eV and a high breakdown field of 8 MV cm⁻¹, enabling low‑cost, high‑volume production of single‑crystal substrates for power electronics. Using ozone molecular‑beam epitaxy, high‑quality n‑type Ga₂O₃ epitaxial films were grown and employed to fabricate MESFETs and Schottky barrier diodes on single‑crystal wafers. The MESFETs achieved >250 V breakdown voltage, μA‑level leakage, and a four‑order‑of‑magnitude on/off ratio, while the Schottky diodes exhibited near‑unity ideality and high reverse breakdown, indicating Ga₂O₃ can rival or surpass Si, SiC, and GaN for ultrahigh‑voltage switching.

Abstract

Gallium oxide (Ga 2 O 3 ) is a strong contender for power electronic devices. The material possesses excellent properties such as a large bandgap of 4.7–4.9 eV for a high breakdown field of 8 MV cm −1 . Low cost, high volume production of large single‐crystal β‐Ga 2 O 3 substrates can be realized by melt‐growth methods commonly adopted in the industry. High‐quality n‐type Ga 2 O 3 epitaxial thin films with controllable carrier densities were obtained by ozone molecular beam epitaxy (MBE). We fabricated Ga 2 O 3 metal‐semiconductor field‐effect transistors (MESFETs) and Schottky barrier diodes (SBDs) from single‐crystal Ga 2 O 3 substrates and MBE‐grown epitaxial wafers. The MESFETs delivered excellent device performance including an off‐state breakdown voltage ( V br ) of over 250 V, a low leakage current of only few μA mm −1 , and a high drain current on/off ratio of about four orders of magnitude. The SBDs also showed good characteristics such as near‐unity ideality factors and high reverse V br . These results indicate that Ga 2 O 3 can potentially meet or even exceed the performance of Si and typical widegap semiconductors such as SiC or GaN for ultrahigh‐voltage power switching applications.