Stability and electronic structures of native defects in single-layerMoS2

We investigate the native defects, the Mo substitutional impurities of the\ngroup-VB and -VIIB elements, and the S substitutional impurities of the\ngroup-VA and -VIIA elements in single-layer MoS2, through density-functional\ntheory calculations. It is found that the S-vacancy (V_S) and S-interstitial\n(S_i) are low in formation energy, about ~1 eV, in Mo- and S-rich conditions,\nrespectively, but the carrier doping ability of the V_S and S_i is found to be\npoor, as they are deep level defects. The V, Nb, and Ta (group-VB) and Re\n(group-VIIB) impurities are found to be easily incorporated in single-layer\nMoS2, as Mo substitutional defects, where the V, Nb, and Ta are shallow\nacceptors and the Re is the only shallow donor among the considered. The\nunintentional n-type doping in single-layer MoS2 exfoliated from the naturally\ngrown MoS2 bulk materials is suggested to originate from the Re impurity.\n