Crystalline β-Ga2O3 thin films deposited via reactive magnetron sputtering of a liquid Ga target

Ga2O3 thin films were deposited by reactive magnetron sputtering from a liquid gallium target at a fixed oxygen partial pressure of 0.1 Pa. The influence of deposition temperature, substrate type, and discharge parameters on the structural and electrical properties was systematically investigated. Films deposited on silicon and quartz glass exhibit polycrystalline growth, whereas sapphire substrates enable highly oriented growth of β-Ga2O3 with a preferred (−201) orientation. The lowest electrical resistivity of 7 × 103 Ω cm was obtained for films deposited on sapphire at a temperature of 585 °C. At this temperature, the films reach sufficient crystalline quality to enable efficient charge carrier transport and, thus, the manifestation of unintentional conductivity. At higher deposition temperatures, pronounced crystallization occurs; however, it is not homogeneous throughout the entire film thickness, which leads to a deterioration of the electrical properties. These results demonstrate that, despite intrinsic limitations, reactive magnetron sputtering can be successfully employed for the preparation of Ga2O3 thin films with optimized electrical properties when appropriate substrates, oxygen partial pressure, and deposition temperatures are selected.