XPS studies of chemically etched surfaces of (La,Sr)(Al,Ta)O3 single crystals

The electronic structure measurements of three LSAT single crystals, annealed in hydrogen atmosphere at 900-1400 degreesC for I or 4 h, slowly or rapidly cooled were performed. The existence of core level peak satellites at the lower binding energy site were found. These satellites may be related to the defect states. The crystal annealed at 1400 degreesC and slowly cooled has the smallest low binding energy satellites. For La 3d, besides the satellites at lower binding energy (S-II), the satellites (S-I) at higher binding energy to the main peak (M) were detected. It was found that the area peak ratio I-M/I-SI of the La 3d states is not sensitive to the annealing, polishing or treatment with HCl and HNO3:HF of the wafer surfaces. Contrary to that, the area peak ratio I-M/I-SII depends on such treatment. The XPS results show that the treatment of the surface with HNO3:HF increases the roughness of the surface which confirmed the AIM results and showed that the surface chemical composition changes with processing. (C) 2003 Elsevier B.V. All rights reserved.