X-ray photoelectron spectroscopy of etched ZnSe

Abstract

To produce longitudinal ZnSe laser structures the GaAs substrate must be removed from the MBE grown layers. When an aqueous solution of sulfuric acid and hydrogen peroxide was used for this purpose, a red film was left on the surface of the ZnSe. X-ray photoelectron spectroscopy was used to examine the wafers before etching, after etching and after etching followed by heating in vacuum or in an argon atmosphere. The as-polished surface contained Se in two different chemical states: ZnSe and Se oxide. The etch predominantly removed the Zn leaving a red Se-rich surface with mostly Se-Se bonding. The Zn Auger parameter decreased toward that of the oxide. The etched surface could be restored to ZnSe by heating in vacuum but not in an argon atmosphere. The one heated in the argon showed the Se Auger parameter approaching that of ZnSe while the Zn Auger parameter increased past that of ZnSe toward metallic Zn.