Effect of Wavelength and Intensity of Light on a-InGaZnO TFTs under Negative Bias Illumination Stress

Abstract

We investigated degradation mechanism of a-IGZO TFTs under NBIS with different wavelengths. and intensities IL of light. Negative gate bias was applied for 4000 s while drain and source were grounded, and illuminations with lambda = 450, 530, or 700 nm were applied. Illumination with photon energy exceeding similar to 2.3 eV (530 nm) induced noticeable change in threshold voltage shift Delta V-th, which can be interpreted in terms of ionization of oxygen vacancies V-O. In addition, I-L of blue illumination (450 nm) was varied from 6 to 200 lux and saturation in Delta V-th was observed after exceeding a certain I-L. We suggest that the saturation occurs because V-O-ionization rate is saturated by outward relaxation of metal atoms in the a-IGZO film. (C) The Author(s) 2016. Published by ECS.