Negative bias illumination stress instability in amorphous InGaZnO thin film transistors with transparent source and drain

Abstract

The investigations on the device instabilities in amorphous InGaZnO TFTs with metal (Ni) and transparent (ITO and InGaZnO) source and drain electrodes have been performed under negative bias stress (NBS), negative bias thermal stress (NBTS), negative bias illumination stress (NBIS) and negative bias thermal and illumination stress (NBTIS). From the measured device parameters in dark and under illumination conditions, a-IGZO TFTs with InGaZnO source and drain show an excellent device performances and lower device degradation than the devices with Ni and ITO source and drain under NBS and NBTS. However, amorphous IGZO TFTs with InGaZnO source and drain electrodes show more significant device degradation under NBIS and NBTIS. In order to explain our experimental results, we propose that the center responsible for the device instability is the process-related defects under NBS and NBTS, and the oxygen vacancy under NBIS and NBTIS, respectively.