STM/STS investigations of titanium oxide nanostructures on au substrate

Au substrate was prepared by Au evaporation on Si(111) surface. Au surface was composed of Au grains with typical diameter of about 50 nm with atomically flat terraces. TiO 2 nanostructures were created by electron gun evaporation of Ti while simultaneous dosing of high purity O 2 gas. The pressure of oxygen was kept at 5 · 10 − 8 mbar and controlled by means of residual gas analyzer (RGA). Scanning tunneling microscopy (STM) images showed that TiO 2 nanocrystallites had grown between Au grains in cavities between them. This may suggest that such spots are preferred TiO 2 nucleation sites. I– V curves measured above Au showed metallic properties while those measured above TiO 2 exhibit energy gap characteristics for semiconducting material.