An Empirical Defect-Related Photo Leakage Current Model for LTPS TFTs Based on the Unit Lux Current

Abstract

In this paper, the photosensitive effect of n-type low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) after dc stress is analyzed. It is found that the illumination behaviors for poly-Si TFTs are dependent on the defect types created by different stress conditions of hot-carrier and self-heating effects. For a given stress-induced device degradation, the anomalous illumination behaviors are observed, and these photo-induced leakage currents are not included in the present SPICE device model. Therefore, based on trap-assisted and Poole-Frenkel effect, an empirical defect-related photo leakage current model based on Unit Lux Current (ULC) is proposed to depict the photo-induced current after device degradation. Furthermore, the verified equation of ULC is analytically derived and has good agreement with the experimental data.