A high-performance broadband phototransistor array of a PdSe₂/SOI Schottky junction

There is great interest in the incorporation of novel two-dimensional materials into Si-based technologies to realize multifunctional optoelectronic devices via heterogeneous integration. Here, we demonstrate a gate-tunable, self-driven, high-performance broadband phototransistor array based on a PdSe₂/Si Schottky junction, which is fabricated by pre-depositing a semi-metallic PdSe₂ film on a SOI substrate. In addition, thanks to the zero bandgap of the PdSe₂ material and the PdSe₂/Si vertical heterostructure, the prepared phototransistor exhibits pronounced photovoltaic properties in a wide spectral range from ultraviolet to near-infrared. The responsivity, specific detectivity and response time of the device at the incident light wavelength of 808 nm are 1.15 A W^-1, 9.39 × 10¹⁰ Jones, and 27.1/40.3 μs, respectively, which are better than those of previously reported PdSe₂-based photodetectors. The photoelectric performance can be further improved by applying an appropriate gate voltage to the phototransistor and the responsivity of the device increases to 1.61 A W^-1 at V_G = 5 V. We demonstrate the excellent imaging capabilities of a 4 × 4 array image sensor using PdSe₂/SOI phototransistors under 375 nm, 532 nm, and 808 nm laser sources.