Gregory L. Hansell

Novel Thin-Film α-Si Approach to Drive Active Matrices Displays

High information content liquid crystal displays (minimum 250 × 250 picture elements) operated in the fast update (TV) mode require the incorporation of an electronic switch into each picture element. α-Si:H(F)1 is a suitable material for the implementation of both two (diode) and three (TFT) terminal devices for matrix addressed LCDs. A simple analysis of α-Si TFTs shows that the low mobility of α-Si is an optimal match to the Ioff requirements. while competing technologies (CdSe, poly-Si) encounter difficulties. However. using 10μ channel lengths, the mobility of α-Si was considered insufficient to drive active matrix displays. We report an innovative α-Si TFT which achieves short channel length and high mobility. The DC and the transient response characteristics will be presented. Ring oscillators were designed using this characteristic. Computer simulations suggest that an eleven stage ring oscillator utilizing α-Si TFTs can operate at 2.2 MHz. These advances will allow us to overcome the limitations ...