Crystal Growth Promotion Enables High-Performance Te0.7Se0.3 Thin-Film Shortwave Infrared Photodetector for Multispectral Imaging Applications

Abstract

Tellurium-selenium (Te_xSe_1-x) alloy compound is considered as an excellent light absorber layer for thin-film photodetector applications, owing to its suitable bandgap and excellent optoelectronic performance. Recently, the research on Te_xSe_1-x photodetectors has achieved considerable progress, especially under electron and/or hole transport layer engineering to improve the device responsivity. However, the intrinsic growth mechanism of Te_xSe_1-x thin film still needs investigation. In this work, based on the analysis of crystal growth thermodynamics and kinetics, Te_0.7Se_0.3 light absorber with optimal (100) growth orientation can be achieved through thermal evaporation of pre-alloyed Te_0.7Se_0.3 powder and atmosphere-assisted slow thermal annealing of Te_0.7Se_0.3 thin film. Thanks to the optimized Te_0.7Se_0.3 light absorber and Te_0.7Se_0.3/ZnO heterojunction interface, the champion self-powered thin-film photodetector possesses a wide spectral response range of 300–1600 nm, minimized dark current density of 3.1 × 10⁻⁵ mA cm⁻², accompanied with satisfactory responsivity of 0.06 A W⁻¹ and detectivity of 5.9 × 10⁹ Jones at 1300 nm, and linear dynamic range exceeding 101 dB. Interestingly, an imaging system based on this photodetector can achieve high-precision color imaging and multispectral imaging from visible light to short wave infrared light, highlighting the intriguing application potential of Te_0.7Se_0.3 photodetectors.