Fig. 2
From: Reconfiguring crystal and electronic structures of MoS2 by substitutional doping
Beyond the 2H–3R structural transition: Restructuring of valence bands in bilayer Nb-doped MoS2. a High-resolution transmission electron microscopy (HRTEM) images of typical bilayer (2L) MoS2 and Nb-doped MoS2 flakes. The insets show a modeled top view of 2H and 3R MoS2 bilayers with violet and yellow spheres corresponding to Mo and S atoms, respectively, and are superimposed onto the HRTEM images. Here the existence of Nb dopants is not presented due to its substitutionality and indistinguishability from Mo in HRTEM (ZNb = 41 and ZMo = 42). Scale bars, 1 nm. b Room temperature photoluminescence (PL) spectra of 2L MoS2 including both 2H and 3R structures, and MoS2:Nb with three representative doping concentrations. The arrow line shows the evolution of indirect bandgap to guide the eye. c Calculated partial density of states (PDOS) of 2L undoped and Nb-doped MoS2 (3R-stacked) projected onto the selected atoms, Mo, Nb and S. For the bilayer MoS2:Nb, one of the 72 Mo atoms is substituted with a Nb dopant atom (corresponding to 1.4% doping) to match the experimental doping level. Also, two representative Mo atoms, the nearest to and remote away from Nb dopants, are shown here to resolve their distinct contributions to the valence band maximum
