Effect of Tip Induced Strain on Nanoscale Electrical Properties of MoS2-Graphene Heterojunctions
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 (MoS2) 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 MoS2, 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 MoS2 with metal contacts in novel 2D materials based devices.
The authors would like to thank FIST (DST Govt. of India) UFO scheme of IIT Delhi for providing the Raman facility. Vishakha Kaushik would like to thank the Council of Scientific and Industrial Research (CSIR), India, for providing the financial help in the form of Senior Research Fellowship.