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

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The density of states (DOS)-based DC <formula formulatype="inline"><tex Notation="TeX">$I$</tex></formula>– <formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula> model of an amorphous gallium–indium–zinc oxide ( <formula formulatype="inline"><tex Notation="TeX">$a$</tex></formula>-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 <formula formulatype="inline"><tex Notation="TeX">$(\phi_{S})$</tex></formula> and gate voltage <formula formulatype="inline"><tex Notation="TeX">$(V_{\rm GS})$</tex></formula>, it is verified that the proposed DC model reproduces well both the measured <formula formulatype="inline"><tex Notation="TeX">$V_{\rm GS}$</tex></formula>-dependent mobility and the <formula formulatype="inline"><tex Notation="TeX">$I_{\rm DS}$</tex></formula>–<formula formulatype="inline"> <tex Notation="TeX">$V_{\rm GS}$</tex></formula> characteristics. Finally, the extracted DOS parameters are <formula formulatype="inline"><tex Notation="TeX">$N_{\rm TA} \! =\break \! \hbox{4.4} \! \times \! \hbox{10}^{17}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$N_{\rm DA} \! = \! \hbox{3} \! \times \! \hbox{10}^{15}\ \hbox{cm}^{-3} \cdot \hbox{eV}^{-1}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$kT_{\rm TA} \! = \break \hbox{0.023}\ \hbox{eV}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$kT_{\rm DGA} = \hbox{1.5}\ \hbox{eV}$</tex></formula>, and <formula formulatype="inline"><tex Notation="TeX">$E_{O} = \hbox{1.8}\ \hbox{eV}$</tex> </formula>, with the formulas of exponential tail states and Gaussian deep states. </para>