MOCVD growth and characterization of conductive homoepitaxial Si-doped Ga₂O₃

Epitaxial Ga₂O₃ films were grown by Metal Organic Chemical Vapor Deposition (MOCVD) on native substrates at growth rate of 1 µm/hour. The electron conductivity was introduced in the films through Si doping during deposition and the growth and doping parameters were optimized to control the electrical transport properties. The films were characterized in terms of structure, surface morphology, electrical transport properties, dopant concentrations and trapping defects. It was found that electron densities are not solely dependent on dopant concentrations and the use of metal organic precursor seems to induce additional donors of carbon. The work shows that the electron density and conductivity of MOCVD Ga₂O₃ films are mainly governed by the interplay between dopant concentration, C concentration and the presence of trapping defects in the films, which is most likely applicable for other oxide films grown by MOCVD. Conductive films of Ga₂O₃ with resistivity in the order of 0.07 Ω.cm were successfully grown. The electron density in most of these films was in the range of 10¹⁹ cm⁻³ but the mobility was limited to 1.5 cm²/V⋅s. Higher mobility of 30 cm²/V⋅s was obtained in some films at the expense of carrier concentration by reducing Si doping level resulting in resistivity in the order of 0.3 Ω.cm. This range of conductivity and mobility is relevant for field-effect transistors (FET) and the applications of Ga₂O₃ as transparent FET in Deep Ultra-Violet (DUV) technology.