X-ray photoemission studies of the valence bands of nine IV-VI compounds

Abstract

Valence-band spectra have been obtained by means of x-ray photoemission spectroscopy for the group IV-VI compounds GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbS, PbSe, and PbTe. These spectra, taken under ultrahigh-vacuum conditions with unmonochromatized Mg x rays, are presented and discussed in terms of previously reported valence-band spectra and band-structure calculations. It is observed that the valence bands of the orthorhombic structured compounds (GeS, GeSe, SnS, and SnSe) which have not been previously reported and for which no band-structure calculations have been published are closely related to those of the NaCl-structured compounds despite the two-dimensional character of the orthorhombic structure.