Self-Consistent Technique for Extracting Density of States in Amorphous GaInZnO Thin Film Transistors by Combining an Optical Response of C-V Curve and Gate Voltage-Dependent Intrinsic Channel Mobility

The self-consistent technique for extracting density of states (DOS: g(E))in amorphous Gallium-Indium-Zinc-Oxide (a-GIZO) thin film transistor (TFT) is proposed and demonstrated. While the energy level (E) is scanned by the photon energy and the gate voltage (VGS) sweep, its density is extracted from the optical response of capacitance-voltage (C-V) characteristics. The preliminary DOS assuming the linear relation between VGS and E is translated into the final DOS by fully taking nonlinear relation between VGS and E into accounts. It is finally extracted and verified by finding the self-consistent solution satisfying both the preliminary DOS and the measured VGS-dependence of intrinsic channel mobility (µCH) with the numerical iteration of DOS-based µCH model. final DOS parameters are NTA=1.73×1017 [cm-3 · eV-1], NDA=3.5×1015 [cm-3 · eV-1], kTTA=0.023 [eV], kTDGA=1.2 [eV], and EO=1.7 [eV] with the formula of exponential tail states and Gaussian deep states