Crystalline characteristics and solar-blind photodetecting performances of β-Ga2O3 film grown on silicon thermal oxide wafer using an EBV method

Abstract

The fabrication of Ga₂O₃ film solar blind photodetectors on silicon thermal oxide wafers using an electron beam evaporation technique is reported in this work. The crystalline structure of the Ga₂O₃ film was varied by applying variant annealing temperatures from 600 to 1000 °C. The effect of annealing temperature on the crystalline structure, surface morphology and optical properties of the Ga₂O₃ films was analyzed using a couple of sophisticated techniques including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, spectroscopic ellipsometry and ultraviolet-visible spectroscopy. The as-deposited films were found to be amorphous. However, all the annealed films were observed and it was found that they were made of phase-pure β-Ga₂O₃ with an increasingly higher crystal quality of the (400) orientation as the annealing temperature increased. The detailed photoresponse measurements showed that, among all the films, the 800 °C annealed film displays the best comprehensive photoresponse characteristic with the highest I_photo/I_dark ratio of 5.15 × 10³ as well as rapider response times of 0.59 s for the rise phase and 0.15 s for the decay phase. The results in this work reveal that β-Ga₂O₃ films grown on the thermal oxide wafer can realize the combination of low cost and high performance for further applications in solar-blind ultraviolet photodetectors.