Achieving high carrier concentration β-Ga2O3 epilayers via MOCVD using SiCl4 as dopant

Abstract

Gallium oxide (Ga2O3) transparent conductive electrodes and power-device contact layers are critical components for Ga2O3-based electronics. However, the intrinsically low electron mobility (μ) of the (100) plane, which is preferred for large-scale substrate production, under high carrier concentration (n) has hindered device performance and practical deployment. To overcome this bottleneck, we employed unintentionally miscut (100) substrates and optimized thermal and kinetic conditions to achieve step-flow homoepitaxy with ideal surface morphology. Following the elimination of surface Si contamination, in situ Si doping was performed utilizing silicon tetrachloride (SiCl4). SiCl4 proved highly effective for fabricating high-n homoepilayers, yielding films with high crystalline quality, low surface roughness, and more than 80% optical transmittance in the 260–800 nm range. Notably, at a SiCl4 doping flux of 10.4 nmol/min, the homoepilayer exhibited outstanding electrical properties (n = 1.32 × 1019 cm−3, μ = 55.5 cm2 V−1 s−1). These findings not only outperform previously reported results for (100) homoepilayers grown on intentionally miscut substrates but also rival the performance of state-of-the-art (010) plane epilayers.