The anomalous kink effect was investigated in n-type low-temperature polycrystalline silicon thin-film transistors with the source-contacted bottom-shield-metal (SBSM) layer on a polyimide substrate. Using experiments and technology computer-aided design simulation, it was found that the SBSM layer plays a critical role in the anomalous kink effect. The SBSM layer modulated the carrier concentration within the lightly doped drain (LDD) region according to the applied drain voltage (VDS). In addition, this carrier modulation caused changes in the lateral electric field at simultaneously the channel/LDD junction and the LDD/n+ junction. Thus, multiple kink effects, different from the conventional kink effect, occurred in two different VDS regions with different slopes depending on the LDD length (LLDD) and the overlap length (LBSM) between the LDD region and the SBSM layer in the drain region. We propose a novel asymmetric design to suppress the SBSM-induced anomalous kink effect in all VDS regimes. This design has the following requirements with respect to LLDD and LBSM at the drain region: LBSM greater than 1.0 μm,LLDD-LBSM (LLDD) greater than 1.0 μm, and LBSM equal to half of LLDD.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering