STUDY OF O 1S XPS BINDING-ENERGY IN YBA2CU3O7-X

X-ray photoemission measurements were performed on YBa2Cu3O7-x thin fi lms in order to understand the origin and nature of various features a ppearing in O 1s spectra before and after sputtering. The peak appeari ng at 528.8 eV is totally intrinsic and is assigned to the bulk. Peak appearing at about 531.2 eV which has been a subject of controversy, e xtrinsic or intrinsic in origin, is shown to entirely originate from t he unstable surface layer of YBa2Cu3O7-x which is non-superconducting at room temperature under UHV environment. The peak at 530.4 arises be cause of the change in the environment of oxygen atoms present in this non-superconducting layer on sputtering.