On The Leakage Current Mechanism In Non-uniform Film Polycrystalline Silicon TFTs

Abstract

Leakage current mechanism in polysilicon TFTs fabricated on a non-uniform film is investigated. The approach utilizes test structures which have non-uniform film thickness at the drain, source and channel regions. An order of magnitude reduction in leakage current at high drain bias is observed in the thick drain TFT structure compared to the thin drain structure. The improvement on the leakage current is due to the reduction in electric field at the thicker drain. The electric field reduction in the thick drain structure is verified using two-dimensional simulations. The influence of the electric field on the anomalous leakage current is investigated with the grain boundary trapping effects separated out.