Synthesis of β-Ga₂O₃:Mg Thin Films by Electron Beam Evaporation and Postannealing

Doping divalent metal cations into Ga₂O₃ films plays a key role in adjusting the conductive behavior of the film. N-type high-resistivity β-Ga₂O₃:Mg films were prepared using electron beam evaporation and subsequent postannealing processing. Various characterization methods (X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, etc.) revealed that the Mg content plays an important role in affecting the film quality. Specifically, when the Mg content in the film is 3.6%, the S2 film's resistivity, carrier content, and carrier mobility are 59655.5 Ω·cm, 1.95 × 10¹⁴ cm³/C, and 0.53682 cm²/Vs. Also, the film exhibits a smoother surface, more refined grains, and higher self-trapped exciton emission efficiency. The Mg cation mainly substitutes the Ga⁺ cation at a tetrahedral site, acting as a trap for self-trapped holes.