Negative bias illumination stress instability in amorphous InGaZnO thin film transistors with ITO local conducting buried layer

The investigations on the device instabilities of amorphous InGaZnO thin film transistors (a-IGZO TFTs) with ITO local conducting buried layer (LCBL) under the source/drain region and in the middle of the active channel region have been performed under negative bias and illumination stress. From the increased drain current of a-IGZO with ITO LCBL, one can control the drive current by modulating the length of ITO LCBL without changing the ratio of channel width and length. The reason for the less degradation of a-IGZO TFTs with LCBL under negative bias stress than that of device without LCBL was explained by the fact that ITO LCBL could act to reduce the effective energy barrier and act as a hole damping layer. However, the device degradation of a-IGZO with ITO LCBL under negative bias and illumination stress was more significant than that of one without LCBL due to the electron hole pair generation in ITO layer under illumination.