Non-destructive preparation of thin-film Bi2Sr2Ca1Cu2O8+d surfaces for photoemission studies

The nondestructive technique of in situ oxygen annealing is used to prepare clean surfaces of c-axis oriented Bi2(Sr,Ca)3Cu2O8+x thin films. Core and valence level photoemission spectra are consistent with those previously obtained by the authors from ceramic samples. In particular, the density of states at the Fermi level is comparable to that observed from polycrystalline samples but is not consistent with one-electron band-structure calculations.