Electrical Characterization of the Semiconducting Properties of n ‐ TiO2

Electrical measurements of the space‐charge region of , single crystals (rutile) reduced in a hydrogen atmosphere were performed to assess the semiconducting properties of the material prepared with reduction time. For this purpose a rectifying junction was prepared by ion sputtering, with a rear ohmic contact of InGa alloy. Impedance‐spectroscopy measurements were used to investigate the Schottky character of the junction and provide new data on charge‐carrier density for single‐crystal rutile Semiconductors initially prepared by reduction do not show typical Schottky behavior. The electrical characteristics of these initial samples indicate coverage by an insulating surface layer, and infrared spectroscopy measurements suggest that the layer might consist of OH terminal groups. The insulating layer seemed to be decomposed either by further air oxidation followed by a second reduction step, or by intensive water photoelectrolysis, thus yielding characteristic Schottky diodes.