Analysis of dynamic characteristics in a-Si TFT structures (for active-matrix LCD)

Active-matrix LCDs (liquid crystal displays) addressed by a-Si (amorphous silicon) TFTs (thin-film transistors) are being developed for graphic displays such as computer terminals. Three types of TFTs, a back-channel-etched TFT, a trilayered TFT, and a self-aligned TFT, have been developed. The authors describe the dynamic characteristics of these TFTs, especially level shift in pixel voltage. First, the dependence of the level shift voltage both on drain voltage and on gate pulse delay is demonstrated. The difference of the level shift caused by the TFT structure is then clarified. Then these results are compared to those of SPICE simulation.>