Study On Amorphous Ingazno Thin Film Transistors Integrated Gate Driving Circuits For Liquid Crystal Displays

With the development of information display technology,a-Si technology as a main driving TFT backplane technology is increasingly hardly to meet the product specifications of high-end LCD panel requirements such as high resolution,narrow border and low power.While Oxide semiconductors is very suitable for replacing a-Si production line as a TFT channel material for its high mobility,good uniformity,high transmittance and simple fabrication process.In this paper,we tried to apply a-IGZO TFT process to produce GIA circuit,it is found that reliability of conventional integrated gate driver decreased with amorphous InGaZnO thin film transistors(a-IGZO TFTs)employed,which is assumed to result from the threshold voltage shift in both positive and negative temperature bias.Through simulation analysis,we determine that the main reason is the threshold voltage drift of driving TFT.We put forward an improved integrated gate drive circuit.Base on traditional GIA circuit,we keep other TFT components size and driving timing is the same,except for adding T8?T9,delete C2,and change the connect way of T4 &T5 and the device size of T4?T5 and T6.The simulation analysis proves that the gate voltage of the driving TFT is more stably controlled,a large redundancy of threshold voltage drift(from less than +/-3V increase to +/-9V)is obtained,which overcomes the circuit failure caused by threshold voltage drift of a-IGZO TFT,stabilizes the integrated gate driving circuit and prolongs the life of LCD panel.At last,we optimized the layout base on new GIA circuit.