Current rectification and asymmetric photoresponse in MoS2 stacking-induced homojunctions

The layer-dependent electronic and optoelectronic properties in transition metal dichalcogenides (TMDs) have been investigated extensively. Current rectification behavior has been demonstrated using heterojunctions constructed from different TMDs materials, as well as single layer-few layer homojunctions utilizing the layer-dependent behavior of TMDs. MoS2 is the best known TMDs and high quality few-layer samples with different stacking sequences can be facilely obtained by the chemical vapor deposition (CVD) method. In this paper, we firstly report the stacking-dependent junctions formed by the interface of AA-AB stacked bilayer MoS2 samples, together with AA bilayer-single layer (AA-1L) and AB bilayer-single layer (AB-1L) junctions. Current rectification and asymmetric photoresponse are observed for the unique AA-AB junctions, similar to that of bilayer-monolayer (2L-1L) junctions. Current mappings clearly show that the photocurrents are mainly localized along the interfaces, confirming that intrinsic junctions are responsible to their electronic/optoelectronic performances, rather than Schottky barrier between electrode and sample. Our finding demonstrates the promise of using stacking-modulated 2D materials for future electronics and optoelectronics.