Microelectrochemical characterization and modification of semiconductor surfaces with polycrystalline Ti/TiO2 as an example

Different new micro-methods such as anisotropy micro-ellipsometry (AME), photoresist micro-electrochemistry, micro-photocurrent spectroscopy, and UV-laser scanning were performed simultaneously to characterize and modify heterogeneous semiconducter surfaces. All measurements were carried out on single grains with the Ti/TiO2 system as an example. The crystallographic orientations of the substrate grains were determined in-situ by AME. It is shown that both the electronic and the optical properties of the semiconducting TiO2 films sensitively depend on the substrate texture. Film properties such as layer thickness and defect state concentration vary with the substrate orientation in a systematic manner. The TiO2 films were modified at high local resolution by means of focused UV-laser illumination. Both a thickening (writing) or thinning (erasing) of the films could be realized depending on the potential applied during the illumination. Therefore, the anodic potential could be used to control the layer thickness and to generate semiconducting structures with thickness gradients.