AFM AND STM INVESTIGATIONS OF A BI2SR2CACU2O8 HIGH-T-C SUPERCONDUCTOR

The results of the scanning tunneling microscopy and spectroscopy (STM /STS) as well as atomic force microscopy (AFM) measurements on the bis muth cuprate superconductors Bi2Sr2CaCu2O8 (BSCCO) in the a-b plane ar e reported in this paper. Room-temperature STM/AFM has been used to st udy the BSCCO single crystals. Their layered crystalline structure all ows one to prepare them by cleaving the atomically flat surface. Exper iments have shown quits a stability of the cleaved surface and it is p ossible to observe reproducible STM images of the fresh surface in the air. The micromorphology and step heights in the c direction correspo nding to multiple values of the unit cell have been investigated. Init ial tests in air have shown that the STM was able to etch the BSCCO su rface in a layer-by-layer process of subsequent removal of non-metalli c (BiO) and metallic (CuO2) planes. We have also observed large areas with very stable and reproducible tunneling spectra (I-V and dI/dV) as a function of position and tip-sample spacing. Contrary to STM, AFM i maging does not modify the examined surface and reveals the surface co vered with uniformly corrugated (within 1 nm range) granules, arising due to the surface degradation of the BSCCO material.