Fig. 4: Atomic-resolution imaging via conductive atomic force microscopy (C-AFM) and density functional theory (DFT) calculations of electronic structure.

a–c 5 × 5 nm² current images of as-exfoliated (a) and treated (b) MoS₂ samples, and their corresponding Fourier transforms (blue circles highlight bright spots which confirm the hexagonal lattice structure) and (c) their histograms of current, all acquired at a bias voltage (V_bias) of 1 V. Scale bars, Fourier transforms in (a, b), 2.5 nm⁻¹. d Standard deviation of current of as-exfoliated and treated MoS₂. The standard deviation values were calculated from 5 × 5 nm² current maps (See Supplementary Note 11 for the current maps in which the standard deviation values were extracted). Twelve images were analyzed for each of the two monolayer MoS₂ conditions, with four images acquired at each bias voltage: V_bias = –0.5 V, 0.7 V, and 1 V. The central line in each box plot represents the median. The top and bottom edges of the box show the upper and lower quartiles, while the whiskers extend to the maximum and minimum non-outlier values. e–p DFT models (e–h), density of states (DOS) as predicted by DFT (i–l), and electronic density maps as predicted by DFT (m–p), corresponding to pristine monolayer MoS₂ (e, i, and m), monolayer MoS₂ containing a single S vacancy (f, j, and n), monolayer MoS₂ containing a double S vacancy (g, k, and o), and monolayer MoS₂ with a hydrogenated vacancy (h, l, and p). Electronic density maps are shown on the Mo plane, with red representing higher density and blue representing lower density.