Fabrication of β-Ga₂O₃ Schottky Photodetectors With ε-Ga₂O₃ Cap Layer via Temperature-Lowering Process Mist-CVD Heteroepitaxy

In this study, high-performance single-crystal gallium oxide (Ga₂O₃) stack Schottky photodiodes were successfully fabricated using a mist chemical vapor deposition (mist-CVD) process with a temperature-lowering process. By combining X-ray diffraction and electrical analysis, it was found that the low-temperature growth of the cap layer induces a phase transition of β -Ga₂O₃ epitaxially grown on the c plane to the ε -type. This transition provides the device with a higher energy barrier and excellent photodetection performance. The single-crystal unintentionally doped ε -Ga₂O₃ cap layer and single-crystal β -Ga₂O₃:Sn stacked on c plane sapphire substrates exhibited notable photoresponse properties ( Rλ = 448.41 A/W). Compared to Schottky photodiodes with a UID β -Ga₂O₃ cap layer and β -Ga₂O₃:Sn stack, the ε -Ga₂O₃-based device demonstrates a higher effective Schottky barrier high (0.84 eV), superior rectification characteristics ( 2.02 x 10⁶ ), a higher photocurrent-to-dark current ratio (PDCR = 4.12 x 10⁴), and shorter rise and fall response times ( (t_r/t_f =2.4 /9.8 s). The Ga2O3 photodiode fabricated using this method achieves higher performance without the need for another additional material stacking, indicating its potential for significant research and application value in the future.