Interfacial Engineering of Selenium-Based Photodiodes for Extremely Low-Noise Photodetection and Single-Pixel Imaging

Selenium as one of the most historical semiconductors has been used for photovoltaics and photodetection, thanks to its excellent optoelectronic properties, superior stability, facile and low-cost fabrication. However, commercialized Se-based devices are mainly based on its amorphous state, which significantly limits the charge transport and requires relatively large bias voltage. The charge carrier dynamics of high-performance crystalline Se thin films are barely reported, and related photodiodes have not been realized mainly limited by the large dark current and slow response speed. Here, poly-crystalline Se thin films via vacuum evaporation, in situ thermal annealing, and engineered the interfaces with various metal electrodes are fabricated, which resulted in enhanced charge transport properties and reduced device leakage. The optimized Se photodiodes exhibited excellent performance metrics, including extremely low dark current density, decent specific detectivity, and superior stability. Furthermore, the optimized Se photodetectors are also introduced for single-pixel imaging, which demonstrates excellent sensitivity and great potential for real applications. Crystalline Se thin films have been systematically studied for efficient photodetection, mainly focusing on the crystallization and charge transport properties. c-Se-based photodetectors are optimized with interfacial engineering, achieving extremely low dark current and noise, high specific detectivity, and swift response. Prototypical devices for single-pixel imaging, which showed comparable performance metrics with commercial Si-based photodiodes are demonstrated. image