Journal Article 2D materials molybdenum disulfide transition metal dichalcogenides MoS2 growth mechanisms WS2/graphene heterostructure atomic layer deposition buckling chemical doping chemical vapor deposition effective work function electronic-state modulation field effect transistors field-effect transistors graphene wrinkle layer control phase-transition-induced growth precursor chemisorption kinetics strain relaxation topological defect triboelectric nanogenerators triboelectric series