PHOTOEMISSION-STUDY OF CDS HETEROJUNCTION FORMATION WITH BINARY SELENIDE SEMICONDUCTORS

Synchrotron radiation soft x-ray photoemission spectroscopy was used t o investigate the development of the electronic structure at the CdS/C u2-xSe and CdS/In6Se7 heterojunction interfaces. Cu2-xSe and In6Se7 la yers were deposited on GaAs (100) by physical vapor deposition from Cu 2Se and In2Se3 sources. CdS overlayers were then deposited in situ, at room temperature, in steps on these layers. Photoemission measurement s were acquired after each growth to observe changes in the valence-ba nd electronic structure and changes in the In4d and Cd4d core lines. T he results were used to correlate the interfacial chemistry with the e lectronic structure and to directly determine the CdS/Cu2-xSe and CdS/ In6Se7 heterojunction valence-band discontinuities and the consequent heterojunction band diagrams. These results are compared to the valenc e-band offset (Delta E(v)) for the CdS/CuInSe2 heterojunction interfac e.