Investigation of electronic properties of Nd doped PbS

The electronic and optical properties of Nd-doped PbS are investigated by the first-principles calculation and experimental method. Our results indicate that introducing of Nd will enlarge the band gap of PbS slightly, and the doped PbS will be converted to an indirect band-gap semiconductor from a direct band-gap semiconductor. The electronic state of this doped PbS system eventually exhibits a good ferromagnetism, in which Nd (4f) states play an important role. The calculated refractive index and extinction coefficient are basically consistent with the experimental values. This study will help us to understand how Nd-doping affects the electronic properties of PbS.