Photoresponse in metallic layered transition metal dichalcogenides

Photocurrent generation is a key process in optoelectronics. In recent years, photoresponse from semiconducting layered transition-metal dichalcogenides have been studied extensively with the hope of finding applications in flexible optoelectronics as well utilising the new degrees of freedom. Photocurrent generation in metallic transition metal dichalcogenides, however, is unexpected as the possible mechanisms for the photoresponse are typically not prevalent for several reasons. In this report, using scanning photocurrent microscopy, we show a significant photoresponse from thin layered metallic transition metal dichalcogenides. In particular we studied thin metallic niobium disulfide flakes (3R) and explain the possible underlying mechanisms.