Performance Optimization of β-Ga₂O₃-Based Solar-Blind Photodetector by Introducing an Ultra-Thin Sn-Doped High Conductivity Layer

The metal/semiconductor (M/S) contact plays a crucial role in carrier collection efficiency and is a key factor in photoelectric conversion. To optimize the M/S contact of Al and $\beta $ -Ga2O3, several annealing procedures were explored, including low-temperature annealing, direct Sn layer deposition, and face-to-face annealing. Among these methods, the $\beta $ -Ga2O3-based solar-blind photodetector fabricated using face-to-face annealing—incorporating an ultra-thin Sn-doped high-conductivity layer—demonstrated superior performance. This device achieved an exceptionally high light-to-dark current ratio of $1.71\times 10{^{{8}}}$ , with a responsivity of 14.13 A/W and a detectivity of $1.87\times 10^{16}$ Jones at a 10 V bias under 255 nm irradiation ( $23.75~\mu $ w/cm2 light intensity). Additionally, it is capable of providing quick signal feedback, with a decay time of 2.81 ms/72.46 ms. The enhanced performance of the face-to-face annealing method is attributed to the formation of a more uniform ultra-thin Sn-doped conductive layer. This layer effectively lowers the barrier height at the M/S interface, improves carrier migration, and reduces contact resistance. These findings highlight that interface engineering through Sn-doped conductive layers is a promising strategy for optimizing the performance of $\beta $ -Ga2O3-based photodetectors.