UV-SWIR broad range photodetectors made from few-layer α-In2Se3 nanosheets

Abstract

Photodetectors are very important for many applications. However, inexpensive infrared photodetectors with high performance at room temperature are still rare. Furthermore, it is still a great challenge to realize on-chip wide-spectrum detection by using conventional photodetectors. van der Waals semiconductors are promising for high performance optoelectronic devices. Here, we report broad range photodetectors made from few-layer α-In₂Se₃ nanosheets. The photodetectors show response in an unexpected broad range from ultraviolet (325 nm) to short-wavelength infrared (1800 nm) at room temperature. The optical response in the long wavelengths beyond the bandgap is attributed to oxygen absorption and oxygen-associated selenium defects in In₂Se₃, supported by theoretical simulation and controlled experiments. High responses to 700 nm and 1550 nm lasers are demonstrated on the same In₂Se₃ device. The stability of In₂Se₃ under the atmosphere at room temperature and the low power consumption of the devices make the In₂Se₃ photodetectors promising for optoelectronic applications.