Effect of Temperature on Poly Crystalline Zinc Oxide thin Film Transistor

Abstract

The effect of temperature on the electrical characteristics of a on polycrystalline zinc oxide thin film transistor (pc-ZnO TFT ) using numerical simulation is studied. The transfer characteristics of the pc-ZnO TFT were computed. The threshold voltage and the electric field mobility were extracted from these transfer characteristics. The drain current shows Arrhenius-type dependence with temperature. The activation energy varies almost linearly from 0.52 eV at VGS=0 V to 0.05 eV at VGS=24 V. This means that this dependence is very strong in the subthreshold regime while it is inactivated beyond threshold voltage. The threshold voltage and the electric field mobility were also found to be thermally activated. This temperature dependence is attributed to the contribution of the density of states to the channel electrons in the sub-threshold region. However the contribution of DOS beyond threshold voltage is negligible. Furthermore, the threshold voltage was found to be proportional to the electric field mobility. The temperature dependence of the pc-TFT transfer characteristics were qualitatively compared to measurements carried out on pc-ZnO TFTs.
Keywords:

Poly-crystalline ZnO; TFT; Temperature; TCAD simulation.