X-Ray photoelectron spectroscopy study of CdTe oxide films grown by rf sputtering with an Ar-NH3 plasma

CdTe oxide films were prepared on glass substrates using the rf-sputtering technique and a controlled plasma of Ar-NH3. Films were studied by X-ray photoelectron spectroscopy and X-ray diffraction. The changes in chemical composition as a function of NH3 partial pressure during deposition indicate that oxygen incorporates in the films up to approximately 62 at.%, while the Cd and Te contents decrease from similar to 43 to 19 at.%. At NH3 partial pressure of 1.3 x 10(-2) Pa, the Te-Cd bonds are strongly reduced and the Te in the films is mainly bonded to oxygen. The Cd MNN X-ray Auger feature shows a shift in energy of approximately 0.8 eV as a function of NH3 partial pressure. This shift appears to be related to the change in Cd bonding from Cd-Te to Cd-O. Films prepared at NH3 partial pressure of 4 x 10(-4) Pa present crystallinity with a [111] cubic CdTe orientation, while those prepared at higher NH3 partial pressure show an amorphous Structure. The amorphous material formed at NH3 partial pressure saturation appears to be mainly amorphous CdTeO3. (C) 2002 Elsevier Science B.V All rights reserved.