Observation of SrTiO3-Ceramic Surface by Tunneling Spectroscopy

The tunneling current-voltage characteristics of SrTiO3 ceramics were determined in air and in vacuum. The experimental results obtained immediately after polishing and etching with a HF solution showed that inhomogeneous adsorption occured on the surface, and that the surface states were affected by the adsorption. The results obtained after the thermal treatment in vacuum showed that there was no inhomogeneous adsorption layer. In both cases, it was suggested that space charge layers were formed at the surface of SrTiO3 ceramics.