High-Speed and Broadband n-Si/p-Se0.3Te0.7/ITO Heterojunction Photodetector

Abstract

The prevailing short-wavelength infrared (SWIR) photodetectors (PDs) based on III-V materials face challenges in heteroepitaxial material growth and device fabrication which adds cost and complexity. SeTe alloy is a potential candidate for SWIR PDs due to its low-cost growth and adjustable bandgap. However, the performance of SeTe-based PDs is currently hindered by the narrow depletion region and high dark current. Herein, large-scale, high-quality Se_0.3Te_0.7 thin film is fabricated through a CMOS-compatible magnetron sputtering method followed by a low-temperature annealing process. A Si/Se_0.3Te_0.7/ITO vertical heterostructure is constructed with enhanced performances induced by an internal photoemission effect of top Schottky diode, which significantly increases carriers injected into Se_0.3Te_0.7 and transported by Si/Se_0.3Te_0.7 heterojunction. The PD shows superior broadband photoelectric properties with a 10000% improved responsivity at 1310 and 1550 nm, and a response time of ≈20 µs over a wide spectral range which represents a 100-fold reduction compared to traditional devices in the absence of hot holes trapping mechanism. This pioneering research provides fresh avenues for significantly improving the optoelectronic performance of analogous devices with narrow depletion regions in photosensitive materials and showcases potential applications in Si-based broadband detection and imaging systems with high sensitivity and high speed at room temperature.