Electron-paramagnetic-resonance studies on arsenic acceptors in natural (2H) and synthetic (3R) MoS2 crystals

Abstract

We have observed the EPR spectra of As acceptors in both natural MoS2 crystals (2H polytype) and in synthetic MoS2 crystals (3R polytype). The g values of the resonance signals show that the As acceptors are associated with a band that has dz2 orbital character. Energy considerations indicate that the As acceptors are most likely substitutional on sulfur sites. The observation of dz2 orbital character for the As acceptors on sulfur sites is only consistent with a MoS2 band structures that has the dz2 band as the highest filled band. In one of our samples the concentration of As acceptors was low enough so that some of the holes introduced by the As acceptors were localized at the As impurity. For these centers we were able to observe an As75 hyperfine structure in the EPR spectrum. We determine from this hyperfine structure a value of 1r3=2.99 a.u. for the hole orbit around the As and a value for the nuclear electric quadrupole moment of As75, q=0.28 b. © 1973 The American Physical Society.