Effects of seed layer thickness and post-annealing process on crystalline quality of β-Ga2O3 films prepared on Si (100) substrate by RF magnetron sputtering

Abstract

Ga2O3 films were deposited on Si (100) substrates via radio frequency magnetron sputtering at room temperature. The large lattice mismatch between Ga2O3 and single crystal Si resulted in poor crystalline quality and cracking of the as-deposited Ga2O3 films. To improve the crystalline quality of the Ga2O3 films and promote the combination of Ga2O3 materials with the current Si-based process, a method combining pre-deposited β-Ga2O3 seed layer and post-annealing process was proposed. Structure, morphology and composition tests showed that when the seed layer was 9 nm and the annealing temperature was 800 °C, the prepared film was high crystalline quality β-Ga2O3 growing along a single (2‾ 01) out-of-plane orientation, and the film thickness was about 160 nm. The seed layer provided nucleation sites for the β-Ga2O3 films, which alleviated the lattice mismatch between the β-Ga2O3 films and Si substrates and prevented the film from cracking. In addition, the appropriate annealing temperature could promote the recrystallization of the film, thereby improving the quality of Ga2O3. This work will promote the development of highly integrated and low-cost Ga2O3-based optoelectronic and power devices on Si substrates. In the meantime, it also contributes to solving the problem of poor heat dissipation of Ga2O3 devices.