ROle of top nitride layer on stability and leakage current in a-Si:H thin flm transistors

摘要

In this paper, we discuss the rle of top (passivation) nitride layer on stability and leakage current characteristics in inverted staggered hydrogentated amorphous silicon (a-Si:H) thin film transistors (TFTs). Here, we varied the ammonia (NH_3) to silane (SiH_4) gas ratio (R chemical bounds NH_3/SiH_4) of the top nitride layer from 5 to 25 for a fixed composition of the (ntrogen-rich) gate nitride. When stressed with a prolonged gate bias, the observed shift in both threshold votage (V_T) and leakage current was largest in samples where the gas ratio was smal (R chemical bounds 5). THis behavior can be attributed ti injection of energetic carriers frm the a-Si:H and their subsequent trapping in the top a SiN_x:H layer which can be minimized by use of nitrogenrich top- nitride (R chemical bounds 25).