Analytical Models for Drain Current and Gate Capacitance in Amorphous InGaZnO Thin-Film Transistors With Effective Carrier Density

Abstract

Analytical drain current and gate capacitance models for amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) over sub- and above-threshold regions are proposed by adopting an effective carrier density for the dominant carrier density. The effective carrier density fully considers the free carriers in the conduction band, the localized subgap deep states, and tail states over the bandgap for analytical <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> characteristics. The proposed analytical models are verified by comparing the measured <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> characteristics. The proposed models make a time-efficient simulation of a-IGZO TFT-based circuits possible due to their analytical form.