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

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.