The lead acceptor in p-type natural 2H-polytype MoS₂ crystals evidenced by electron paramagnetic resonance

A low-temperature (T  =  1.5-8 K) electron paramagnetic resonance study of p-type 2H-polytype natural MoS₂ crystals reveals a previously unreported anisotropic signal of corresponding defect density (spin S  =  ½) ~5  ×  10¹⁴ cm^-3. For the applied magnetic field B//c-axis, the response is comprised of a single central asymmetric Zeeman peak at zero-crossing g  =  2.102(1), amid a symmetrically positioned hyperfine doublet of splitting 6.6(2) G. Field angular observations reveal a two-branch g pattern, indicative of a defect of lower than axial symmetry, likely orthorhombic (C _2v). Based on the signal specifics, it is ascribed to a system of decoupled Pb impurities substituting for Mo, the defect operating as an acceptor, with estimated thermal activation energy  >10 meV. Supporting theoretical anticipation, the results pinpoint the conduct of the Pb impurity in layered MoS₂.