DEVICE ANALYSIS FOR A-SI-H THIN-FILM TRANSISTORS WITH ORGANIC PASSIVATION LAYER

Two dimensional device analysis has been performed to explain the expe rimental drain current-gate voltage (I-D-V-GS) characteristics of hydr ogenated amorphous silicon thin-him transistors with various passivati on layers. The shift of the I-D-V-GS curve in the negative direction a nd the increase of S-factor (the inverse of subthreshold slope in loga rithmic I-D-V-GS curve) can be explained well by introducing positive fixed charges and defect states in the back interface region. It was f ound that the positive fixed charge and the defect density of a-Si:H T FT with an organic passivation layer are higher than those of conventi onal a-Si:H TFT with a silicon-nitride (SiNx) passivation layer. The s imulation shows that the front and back interfaces interact and this e xplains why the passivation affects the device performance such as V-t h and S-factor in a-Si:H TFT's.