Surface passivation enhanced β-Ga2O3-based solar-blind photodetector via introducing an Al2O3 ultrathin layer

The surface properties of semiconductor devices have a significant effect on the transport and recombination of charge carriers, especially for planar structures. In this work, Al2O3 ultrathin layers with varying thicknesses (3, 5, and 10 nm) were introduced into β-Ga2O3 thin films to passivate surface dangling bonds. The passivation effect of Al2O3 was verified through surface state analysis. By comparison, it was found that the photodetector (PD) with a 5 nm Al2O3 passivation layer exhibited a high light–dark current ratio of 1.36 × 106, which was 8.4 times higher than the PD on the bare surface. At the same time, it has a high responsivity of 0.38 A/W, a high detectivity of 3.21 × 1012 Jones, and a fast response speed of 1.88 ms/31.46 ms. Combined with simulation results, it was verified that the Al2O3 passivation layer can effectively improve the electric field distribution and current density. This study unravels the role of dangling bonds passivation in β-Ga2O for high-performance solar-blind PDs.