Self-powered, broadband and ultrafast MoS₂/AlN/Si based photodetector

Heterostructures of ultrathin 2D layered materials and wide band gap semiconductors offer possibilities of high-performance electronic devices. The absence of a band gap in graphene, which limits its application as a switch, MoS₂ has attracted considerable attention in recent years due to its excellent optoelectronic properties, as well as the presence of a narrow band gap. Here, we have reported a self-powered, broadband and ultrafast photodetector based on MoS₂/AlN/Si heterostructure. MoS₂ thin film has been deposited on AlN template on n-Si(111) by pulsed laser deposition. The vertical transport of the heterostructure exhibits excellent photodetection properties at zero bias condition. The device shows a broadband photoresponse in the range of 300-1100 nm, with a maximum responsivity of 5.47 A/W at 900 nm. Transient analysis of the device at 900 nm shows an ultrafast detection, with rise/fall times of 12.5/14.9 μs. Band alignment studies of MoS₂ and AlN has been done by XPS and a band diagram of the heterostructure depicting the self-powered transport has been proposed.