VALENCE BAND OFFSET AND INTERFACE CHEMISTRY OF II-VI EPITAXIAL LAYERS GROWN ON THE (110) SURFACE OF III-V MATERIALS

The preparation of II-VI semiconductor layers on III-V semiconductor surfaces, and the in-situ characterization of their electronic structure is reported. Epitaxial layers of CdS on InP(110) as well as ZnTe on GaSb(110) were grown by molecular beam epitaxy (MBE). We describe how information about chemical reactions at the interface, and the growth mode of the overlayers, is derived from core level photoemission. The electronic structure of a heterojunction, and its valence band offset in particular, is derived from valence level spectra for the two cases. CdS/InP(110) is of particular interest since our data show that the CdS layers grow in the metastable zincblende structure. We discuss the valence band offsets in the light of recent models, and compare our experimental values with several semi-empirical and theoretical predictions. © 1989.