Chemical reactivity and band offset at the CdS/Si interface

Abstract

Transport phenomena at heterojunctions are critically governed by chemical reactivity and the valence-band offset at the interface. Here we report our investigations carried out on the CdS/Si(111) interface using X-ray and ultraviolet photoelectron spectroscopy and glancing-incidence X-ray diffraction. Weak reactivity between CdS and Si(111) has been observed. A partial charge transfer interaction is suggested to explain the weak reactivity at the interface on the basis of the electronegativity difference. Hexagonal phase of CdS is preferentially grown at 700 K. The valence-band offsets obtained for the interfaces grown at 300 and 700 K are 1.6 and 1.3 eV, respectively. The effects of chemical reactivity and disorder are discussed.