Ultrafast RTA induced the structural properties of the deficient oxygen β-Ga2O3 film

The RF-sputtered β-Ga2O3 films prepared on sapphire substrates were treated by rapid thermal annealing (RTA) with an ultrafast processing time of 30 s. The effects of RTA at different process temperatures from 600 to 800 °C on the β-Ga2O3 films were researched. Meanwhile, the schematic diagram for the RTA-induced lattice expansion of films was proposed. The experimental results showed that the variation of Ga oxidation states and lattice oxygen was demonstrated, revealing a greater value of lattice oxygen at 700 °C. The (-201) orientation of Ga2O3 films is observed at 700 °C and 800 °C, where the (111) orientation additionally appeared at 800 °C. The larger grain size and interplanar distance of 4.71 Å for the (−201) orientation were also obtained at 700 °C, accounting for the high-quality β-Ga2O3 films and their lattice expansion. As a result, this RF-sputtered β-Ga2O3 films via the RTA process not only provide a new reference condition but also suitable for optoelectronic devices requiring control of crystallizing temperature and lattice variation.