Sulfur-K X-Ray Spectra and Electronic Structure of a Semiconductor Ag₂S

Abstract

The K β emission and K -absorption spectra of sulfur in Ag 2 S are carefully measured and compared with the sulfur K β emission and K -absorption spectra of Cu 1.8 S reported previously. The spectra of Ag 2 S clearly show the existence of the energy gap in semiconducting Ag 2 S in contrast to the metallic phase Cu 1.8 S where the K β band edge overlaps with the K absorption edge. The sulfur- K β emission spectrum of Ag 2 S consists of two prominent peaks. The intensity of the high-energy peak is much greater than that of the low-energy peak, contrary to the sulfur- K β emission spectrum of Cu 1.8 S. It is suggested that the bottom of the conduction band of Ag 2 S arises mainly from the sulfur 4 p states.