Epitaxial insulator for bottom-gate field-effect devices based on TiO2

Field-effect devices with bottom-gate structure based on anatase TiO2 active channels were fabricated. The key factor to achieve this was the quality of epitaxial insulator layers, viz.; the insulating property and their crystallinity, because they work not only as a well insulator for field-effect devices but also as a template for the subsequent growth of epitaxial active layers. Our devices showed typical transistor actions. On-to-off current ratio exceeded 10(4) and the field effect mobility of 0.04 cm(2)/V S were obtained. Interestingly, the device characteristics were found to be sensitive to ambient and light, suggesting their potential for manipulating the fruitful TiO2 surface functions by tuning the gate voltage. (C) 2007 Elsevier B.V. All rights reserved.