Investigation on the relationship between channel resistance and subgap density of states of amorphous InGaZnO thin film transistors

The demand for amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) has increased due to their transparent properties. In this paper, we report on the relationship between the subgap density of states (DOS), field-effect mobility (μ _FE), and unit channel length resistance (r _ch) on the electrical properties of a-IGZO TFTs. The three tested structures had the same channel width/length and gate insulator thickness with different gate insulator materials, SiN _X, SiO _X, and SiO _X/SiN _X. Compared to TFTs with low subgap DOS levels, TFTs with high subgap DOS levels have low μ _FE values due to the relatively large r _ch values.