Enhanced Ultraviolet Detection by Constructing Ga2O3/TiO2 Heterojunction Photodiode Featuring Weak Light Signal Sensing

In this paper, a deep-ultraviolet (DUV) photodetector (PD) based on a Ga 2 O 3 /TiO 2 planar heterojunction is fabricated by both the solution and the metalorganic chemical vapor deposition (MOCVD) methods. The DUV PD demonstrated a range of impressive DUV sensing properties, such as an ultra-high responsivity ( R ) of 275 A/W, a large specific detectivity ( D *) of 6.69 × 10 16 Jones, and an external quantum efficiency ( EQE ) of 1.35 × 10 5 under illumination with light intensity of 0.1 μW/cm 2 at 5 V. The results indicated that the PD had a capacity for weak DUV light signal sensing along with high performance, suggesting high sensitivity. In addition, the DUV PD can operate stably in a self-powered mode. The excellent performance of the DUV PD comes from the creation of the built-in electric field in heterojunction and the dual absorption of DUV light both by the Ga 2 O 3 layer and TiO 2 layer. In all, the achievements in this work may promote the application of sensitive Ga 2 O 3 -based optoelectronics in energy-conserving DUV sensing systems.