Density of States-Based DC $I$– $V$ Model of Amorphous Gallium–Indium–Zinc-Oxide Thin-Film Transistors

The density of states (DOS)-based DC $I$– $V$ model of an amorphous gallium–indium–zinc oxide ( $a$-GIZO) thin-film transistor (TFT) is proposed and demonstrated with self-consistent methodologies for extracting parameters. By combining the optical charge-pumping technique and the nonlinear relation between the surface potential $(\phi_{S})$ and gate voltage $(V_{\rm GS})$, it is verified that the proposed DC model reproduces well both the measured $V_{\rm GS}$-dependent mobility and the $I_{\rm DS}$– $V_{\rm GS}$ characteristics. Finally, the extracted DOS parameters are $N_{\rm TA} \! =\break \! \hbox{4.4} \! \times \! \hbox{10}^{17}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$, $N_{\rm DA} \! = \! \hbox{3} \! \times \! \hbox{10}^{15}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$, $kT_{\rm TA} \! = \break \hbox{0.023}\ \hbox{eV}$, $kT_{\rm DGA} = \hbox{1.5}\ \hbox{eV}$, and $E_{O} = \hbox{1.8}\ \hbox{eV}$ , with the formulas of exponential tail states and Gaussian deep states.