Study on polished and etched surfaces of polar (111) CdTe by x-ray photoelectron spectroscopy and grazing-incidence x-ray diffraction

Several etchants have been applied to polar (111)Cd and (111)Te surfaces of CdTe. Induced surface layers were analyzed by x-ray photoelectron spectroscopy and grazing-incidence x-ray diffraction for studying compositions, chemical states, and crystalline phases of respective layers. A bromine/methanol etch led to a layer composed of mainly tellurium oxides on both (111) surfaces. Oxidation depth, however, was larger at the (111)Te side. Etching with HCl subsequently removed the oxides. A film made of crystalline tellurium was, however, produced with the thickness being larger on the (111)Te surface than on the other surface. A fairly thick layer consisting of TeO2 and crystalline Te for etching with N solution (H2O2:H2O:HF=2:2:3 v/v), formed on both surfaces with the cadmium having been severely depleted, especially on the (111)Te surface.