First-principles investigations and MOCVD growth of Si-doped β-Ga₂O₃ thin films on sapphire substrates for enhancing Schottky barrier diode characteristics

In the realm of high-power electronics, the potential of gallium oxide (β-Ga₂O₃) as a front-runner material has garnered significant attention due to its wide bandgap and the capacity to withstand high critical electric fields. To push the boundaries of performance for β-Ga₂O₃ devices, a meticulous exploration into the effects of silicon (Si) doping on β-Ga₂O₃ films was carried out using the metalorganic chemical vapor deposition (MOCVD) technique with various tetraethoxysilane (TEOS) flow rates (0–30 sccm). The Si-doped β-Ga₂O₃ films were systematically studied and characterized using XRD, SEM, and XPS techniques. XRD patterns demonstrated the preservation of the β-Ga₂O₃ monoclinic structure in the Si-doped β-Ga₂O₃ films, without any evidence of secondary phases. In addition to this, first-principles calculations were performed to explore the incorporation of Si atoms in Ga₂O₃ supercells, which revealed the preference of Si atoms to occupy substitutional Ga tetrahedral sites within the Ga₂O₃ lattice. Through the utilization of Si-doped β-Ga₂O₃ films, a unique design of donut-shaped Schottky barrier diode (SBD) was successfully engineered. Remarkably, the Si-doped β-Ga₂O₃ SBD (employed with 20 sccm TEOS flow rate) exhibited the breakdown voltage (V_br) of 497 V and Baliga's Figure of Merit (BFOM) value of 1.16 kW/cm², which is five-order higher BFOM compared to undoped β-Ga₂O₃ SBD. This substantial improvement in BFOM underscores the significant potential of Si-doped β-Ga₂O₃ films for high-power electronics, opening avenues for enhanced device efficiency and capabilities.