ATOMIC IMAGES OF THE BI-O PLANE ON BI2SR2CACU2O8+DELTA CLEAVED SURFACE BY STM

Atomic images of the semiconducting Bi-O plane on Bi2Sr2CaCu2O8+delta cleaved surface have been observed by STM. For the as-grown crystals, the images show strong modulations in the in-plane atomic interval and in the brightness. The in-plane atomic interval in the relatively bri ght regions (RBR) is 20 similar to 30 % smaller than that in the relat ively dark regions (RDR). It is shown that the density of tunneling el ectrons in RBR is larger than that in RDR, that is, a kind of charge-d ensity-wave (CDW) is formed in the Bi-O plane. Magnitudes of the struc tural modulation and the semiconducting gap are both reduced by anneal ing. Such a correlation suggests that the origin of the semiconducting Bi-O plane might be attributed to the structural modulation.