Photoluminescence characterization of the surface layer of chemically etched CdTe

The effects of several reducing and oxidizing etches on CdTe surfaces have been characterized by photoluminescence. For excitation, several lines from three different types of gas lasers, emitting at 325 nm (He-Cd laser), 488 nm (argon-ion laser), and 632.8 nm (He-Ne laser) were used. The corresponding light penetration depth varied from approximately 25 to 200 nm. The analysis of the photoluminescence as a function of the depth not only allows the characterization of the type of defects created by the etching but also their location from the treated surfaces. Proper etching solutions produce surfaces with a crystalline quality comparable to that of a cleaved surface and the photoluminescence spectra do not depend on the energy of the excitation.