LIQUID-CRYSTAL FLAT PANEL DISPLAYS WITH ACTIVE MATRIX

A large, worldwide, effort has been undertaken to develop liquid crystal flat panel displays with active matrix which combine good optical properties (colors, contrast, view angle) with low power consumption and small size. The first part of this paper gives some details on the driving mode of these flat panels and the requirements on the electrical properties of the thin films transistors (TFT's) associated to each pixel. The second part describes technologies of these TFT's with two types of materials : hydrogenated amorphous silicon and polycristalline silicon. The typical electrical properties and the advantages of each type of these TFT's will be presented. Some aspects on the yield of manufacturing of these active matrix flat panel displays will also be discussed.