Electrical, optical, and magnetic properties of Sn doped α-Ga₂O₃ thin films

We investigated the effect of Sn doping on the optical, electrical, and magneto transport properties of epitaxial α-Ga₂O₃ thin films grown by mist-Chemical Vapour Deposition. Sn introduces a shallow donor level at ∼0.1 eV and has a high solubility allowing doping up to 10²⁰cm⁻³. The lowest obtained resistivity of the films is 2.0 × 10⁻¹Ω cm. The Sn doped films with a direct band gap of 5.1 eV remain transparent in the visible and UV range. The electrical conduction mechanism and magneto-transport have been investigated for carrier concentrations below and above the insulator-metal transition. The magnetic properties of the neutral Sn donor and the conduction electrons have been studied by electron spin resonance spectroscopy. A spin S = 1/2 state and C_3V point symmetry of the neutral Sn donor is found to be in good agreement with the model of a simple Sn_Ga center.