title: Current Rectification through Vertical Heterojunctions between Two Single-Layer Dichalcogenides (WSe2|MoS2pn-Junctions).
abstract: We form junctions between two single layers of p-type WSe2and n-type MoS2in both sequences. The WSe2|MoS2and MoS2|WSe2junctions of ultimate thickness limit exhibit current rectification when characterized vertically with a scanning tunneling microscope (STM) tip. The direction of rectification in the pn-junction is opposite to that of the np-junction, confirming occurrence of the rectification to be due to the junctions themselves. From scanning tunneling spectroscopy (STS) and correspondingly the density of states (DOS), we locate the conduction and valence band edges (CB and VB, respectively) of the materials inferring their single-layer and 2H phase configuration. Band edges of the semiconductors form a type-II band alignment resulting in current rectification. In junctions of WSe2and MoS2with single layers having a partial overlap, we map band edges along different points on individual semiconductors and the overlapped region (junction). The results have provided experimental evidence of current rectification through van der Waals vertical heterojunctions between two single layers.
authors.affiliation: Department of Solid State Physics, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032, India.
authors.forename: Hrishikesh
authors.initials: H
authors.lastname: Bhunia
authors.affiliation: Department of Solid State Physics, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032, India.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Bera
authors.affiliation: Department of Solid State Physics, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032, India.
authors.forename: Amlan J
authors.identifier: http://orcid.org/0000-0002-7651-9779
authors.initials: AJ
authors.lastname: Pal
keywords: 2D single layer; current rectification; density of states; formation of pn-junction between two single layers; p-type WSe2 and n-type MoS2; scanning tunneling spectroscopy