Defect-Mediated Transport in Self-Powered, Broadband, and Ultrafast Photoresponse of a MoS<sub>2</sub>/AlN/Si-Based Photodetector
Deependra Kumar Singh, Rohit Pant, Arun Malla Chowdhury, Basanta Roul, Karuna Kar Nanda, S. B. Krupanidhi
Abstract
By combining unique properties of ultrathin 2D materials with conventional 3D semiconductors, devices with enhanced functionalities can be realized. Here, we report a self-powered and ultrafast photodetector based on a hybrid MoS2/AlN/Si heterostructure. The heterojunction is formed by depositing a MoS2 thin film by pulsed laser deposition on an AlN/Si(111) template. The vertical transport properties of the device under dark and light illumination conditions exhibit an excellent photoresponse in a broad range of wavelengths (300–1100 nm) at 0 V. The maximum responsivity of this photodetector is found to be 9.93 A/W at a wavelength of 900 nm. The device shows an ultrafast temporal response with response/recovery times of 12.5/14.9 μs. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy reveal the presence of native oxygen impurities in AlN throughout the bulk of the film. These oxygen defects form a deep donor level in AlN and play a crucial role in the transport of the photogenerated carriers, resulting in enhanced device performance.