Nanoscale Mapping of Layer-Dependent Surface Potential and Junction Properties of CVD-Grown MoS2 Domains

In the present study, nanoscale variations in the work function values and the resulting changes in junction properties of chemical-vapordeposited 2D MoS2 domains have been investigated as a function of number of layers using Kelvin probe force microscopy and conductive atomic force microscopy techniques. Raman spectroscopy has been employed to obtain the magnitude of difference between E-2g and A(1g) peaks, which has been used as a signature of the number of layers. Surface potential of MoS2 monolayer sample exhibits a value of -427 mV (similar to 7.2 mV for bulk) along with a large spread of similar to 29 mV (similar to 3 mV for bulk). The present study shows that the optical and electronic properties of MoS2 one to two layer samples exhibit a large difference from its bulk counterpart. These characteristic features remain intact, even in the presence of adsorbates and defects, which result in spread in surface potential values and corresponding changes in junction characteristics. These results are important for the application of chemicalvapor-deposition (CVD)-grown MoS2 monolayers for semiconductor devices.