Epitaxial growth of Si-doped β-(In x Ga1− x )2O3 thin films grown on (010) β-Ga2O3 substrates via mist chemical vapor deposition

In this study, Si-doped β-(InxGa1−x)2O3 thin films were grown on (010) β-Ga2O3 substrates by mist chemical vapor deposition. The influence of In composition and strain relaxation on the structural and electron transport properties was investigated for β-Ga2O3-based heterostructure applications. X-ray diffraction and atomic force microscopy measurements revealed that coherently grown films maintained high crystallinity and smooth surfaces with root mean square roughness values below 1 nm, whereas strain relaxation at high In compositions significantly degraded both crystallinity and surface flatness. Hall effect measurements demonstrated that Si doping enabled carrier concentration control under both coherent growth and strain-relaxed conditions. Under coherent growth conditions, Hall mobility decreased with increasing In composition despite comparable carrier concentration and crystalline quality, suggesting enhanced alloy disorder scattering associated with random In substitution. Temperature-dependent Hall measurements revealed degenerate semiconductor behavior with nearly temperature-independent carrier concentration. Analysis of the temperature-dependent Hall mobility based on Matthiessen’s rule showed that temperature-independent scattering (ionized impurity and alloy disorder scattering) accounts for approximately 80% of the total scattering rate even at 300 K, with a phonon-limited mobility of approximately 240 cm2/V s. These findings clarify the influence of In composition on the structural and electrical properties of β-InGaO thin films and provide important insights for β-Ga2O3-based high-electron-mobility heterostructure devices.