Origin of threshold voltage shift by interfacial trap density in amorphous InGaZnO thin film transistor under temperature induced stress

Abstract

Effect of trap-density of amorphous InGaZnO thin film transistors (a-IGZO TFTs) were studied using different analysis of x-ray photoelectron spectroscopy (XPS) depth profile and density of states (DOSs). To change trap-densities systematically, rf-power was varied to cause different effect on the initial growth stage of a-IGZO layer grown on gate insulator. The interfacial trap-density was confirmed to be dominant effect on the performance and the threshold voltage shift of a-IGZO TFT by observing the variation of O1s binding energy from XPS. The relation between temperature stress induced and trap-density in deep level was investigated by analyzing DOSs. (C) 2011 American Institute of Physics. [doi:10.1063/1.3615304]