Experimental characterization of the electronic structure of anatase TiO2: Thermopower modulation

Thermopower (S) for anatase TiO2 epitaxial films (n(3D): 10(17)-10(21) cm(-3)) and the gate voltage (V-g) dependence of S for thin film transistors (TFTs) based on TiO2 films were investigated to clarify the electronic density of states around the conduction band bottom. The slope of the vertical bar S vertical bar-log n(3D) plots was -20 mu V K-1, which is an order magnitude smaller than that of semiconductors (-198 mu V K-1), and the vertical bar S vertical bar values for the TFTs increased with V-g in the low V-g region, suggesting that the extra tail states are hybridized with the original conduction band bottom. (C) 2010 American Institute of Physics. [doi:10.1063/1.3507898]