Extraction Technique for the Conduction Band Minimum Energy in Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors

The conduction band minimum energy in amorphous oxide semiconductor-based thin film transistors (AOS TFTs) is a key parameter governing the accurate extraction of energy distribution for the subgap density-of-states (DOSs) and carrier mobility. We report a technique for extraction of the gate voltage ( \textit{V}_{\text{CBM}}\text{)} and corresponding energy ( \textit{E}_{\text{F,\text{CBM}}} = \textit{E}_{\text{C-\text{EREF}}}\text{)} for the quasi-Fermi level ( \textit{E}_{\text{F}}\text{)} equal to the conduction band minimum ( \textit{E}_{\text{C}}\text{)} as \textit{V}_{\text{CBM}} = \textit{V}_{\text{GS}} ( \textit{E}_{\text{F}} = \textit{E}_{\text{C}}\text{)} and \textit{E}_{\text{F,\text{CBM}}} = \textit{E}_{\text{F}} ( \textit{V}_{\text{GS}} = \textit{V}_{\text{CBM}}\text{)} . In order to confirm this technique through optoelectronic experimental data, amorphous indium-gallium-zinc-oxide (a-IGZO)-based thin film transistor was irradiated with various wavelengths and power, and obtained \textit{V}_{\text{CBM}} = 7.1 V and