Determination of Interface and Bulk Trap Densities in High-Mobility p-type WSe2 Thin-Film Transistors

In this letter, the energy distributions of the interface and bulk trap densities were separately determined in p-type tungsten diselenide (WSe
₂
) thin-film transistors (TFTs) by measuring and analyzing the subthreshold transfer characteristics and space-charge-limited current under the flat-band condition at high drain-to-source voltages. From the experimental results, approximately 79% of the subgap trap states are attributed to the interface states at the valence band edge, which represents that the contribution of the interface trap states is more significant than that of the structural disorder-induced bulk trap states in the subgap density of states of the WSe
₂
TFT. Quantitative information about the separately determined interface and bulk trap densities presented in this letter will facilitate the further development of the fabrication processes to passivate the defect states at the interface in transition metal dichalcogenide-based TFTs, including WSe
₂
TFTs.