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

TL;DR

This study investigates the electronic structure of anatase TiO2 by measuring thermopower and its gate dependence in thin film transistors, revealing insights into the density of states near the conduction band bottom.

Contribution

It provides experimental characterization of the electronic density of states in anatase TiO2 using thermopower measurements and gate voltage dependence, highlighting tail state hybridization.

Findings

The slope of |S|-log n3D plots is -20 μV/K, much smaller than typical semiconductors.

|S| increases with gate voltage in low Vg regions, indicating tail state hybridization.

Tail states are hybridized with the conduction band bottom in anatase TiO2.

Abstract

Thermopower (S) for anatase TiO2 epitaxial films (n3D: 1E17-1E21 /cm3) and the gate voltage (Vg) dependence of S for thin film transistors (TFTs) based on TiO2 films were investigated to clarify the electronic density of states (DOS) around the conduction band bottom. The slope of the |S|-log n3D plots was -20 {\mu}V/K, which is an order magnitude smaller than that of semiconductors (-198 {\mu}V/K), and the |S| values for the TFTs increased with Vg in the low Vg region, suggesting that the extra tail states are hybridized with the original conduction band bottom.