Sn-doped β-Ga₂O₃ thin films grown on off-axis sapphire substrates by LPCVD using Ga-Sn alloy solid source

Abstract

Adopting low pressure chemical vapor deposition (LPCVD), Sn-doped β-Ga2O3 thin films were heteroepitaxially grown on c-plane sapphire substrates with off-axis angles towards <11-20> direction. The influences of off-axis angle on crystal structures, electrical properties, surface morphology, and chemical compositions were thoroughly investigated. As a result, the crystallinity of the β-Ga2O3 films is improved with increasing off-axis angles because in-plane rotational domains are effectively suppressed, demonstrating a full width at half maximum (FWHM) down to 0.64°. Correspondingly, the Hall carrier mobility is promoted from 4.7 to 17.9 cm2/V∙s at carrier concentration of 9×1017 cm-3, which is believed highly competitive among reported Sn-doped β-Ga2O3 films by LPCVD. These results demonstrate an alternative pathway to heteroepitaxially grow high electrical quality n-doped β-Ga2O3 films for the advancement of Ga2O3 materials and devices.