Self-Consistent Technique for Extracting Density of States in Amorphous InGaZnO Thin Film Transistors

Abstract

The self-consistent technique for extracting density of states [DOS: ] in an amorphous indium gallium zinc oxide (a-IGZO) thin film transistor is proposed and demonstrated. The key parameters are the of the a-IGZO active layer and the intrinsic channel mobility . While the energy level is scanned by the photon energy and gate-to-source voltage sweep, its density is extracted from an optical response of capacitance–voltage characteristics. Using the -dependent as another boundary condition, a linearly mapped DOS assuming a linear relation between and is translated into a final DOS by fully considering a nonlinear relation between and . The final DOS is finally extracted and verified by finding the self-consistent solution satisfying both the linearly mapped DOS and the measured dependence of with the numerical iteration of a DOS-based model. The extracted final DOS parameters are , , , , and with the formula of exponential tail states and Gaussian deep states.