Effect of Tip Induced Strain on Nanoscale Electrical Properties of MoS_2-Graphene Heterojunctions

摘要

In the present study, chemical vapor deposited two-dimensional (2D) heterostructures are studied for their interesting electrical, and mechanical properties. The two-dimensional materials, molybdenum disulfide (MoS_2) and Graphene are characterized based on the nanoscale variations in the work function of the heterostructure using kelvin probe force microscopy (KPFM) and electrical properties using conductive atomic force microscopy (CAFM) techniques. Raman spectroscopy has been employed to identify MoS_2, Graphene and study their layer dependence. The surface potential value of the heterostructure exhibits a value of 527 mV, necessary to identify the nature of metal tip contact to be used for its loading force dependence. The I-V characteristics are studied with two different AFM metal tips in contact mode, namely, Cobalt (Co) and Silver (Ag) coated tips, forming an Ohmic contact with MoS2-Graphene heterostructure, theoretically, to probe the junction characteristics. The study emphasizes the critical influence of two-dimensional nature of MoS_2 with metal contacts in novel 2D materials based devices.