Self-powered broadband α-MoO3/Si photodetector based on photo-induced thermoelectric effect

As a two-dimensional crystal, molybdenum trioxides (α-MoO3) has been considered as a typical candidate for next-generation photodetectors (PDs) but with limited photodetection applications in the ultraviolet region. Here, a photo-induced thermoelectric (PTE) effect in α-MoO3 is proposed as a practical approach to realize the broadband photodetection of α-MoO3/Si heterojunction PDs. High-quality α-MoO3 films are grown on Si by using an e-beam evaporation method. By modulating the photo-induced thermoelectric potential along the c-axis on the transport properties, the α-MoO3/Si PDs can be operated as a self-powered device, showing broadband photoresponse beyond the bandgap limitation in the wavelength range of 405–1550 nm. The manipulation of the PTE effect in the heterojunction is investigated carefully, clarifying the corresponding physical mechanisms of the unique photoresponse behaviors. Furthermore, the fabricated device exhibits competitive photodetection performance with a high photoresponsivity of 63.3 mA/W, a high optical detectivity of 3.1 × 1011 cm Hz1/2W−1, fast response speeds with the rise/fall times of 0.47/0.76 ms, as well as high durability and environmental stability under 980-nm infrared illumination. These results not only provide a novel strategy to develop novel PDs with high performance, but also supply a deeply understanding of the PTE effect in α-MoO3/Si heterojunctions.