An alkali-free glass named AN690 was developed for the glass substrates of low temperature poly-Si TFT-LCDs. Low thermal deformation and shrinkage were the main criteria for AN690's glass composition design. Properties of AN690 are presented and compared with Asahi's commercial glasses t~or simple matrix (AS) and a-Si TFT (AN63S) LCD's applications. The comparison of the thermal properties indicates that AN690 exhibits a high thermal stability. The reason for such a behavior is attributed to a high strain point (700℃) which is 100℃ higher than low temperature poly-Si TFT-LCD's processing temperature. Hence AN690 is a good substrate for low temperature poly-Si TFT-LCDs.

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The phase transformation of amorphous silicon by excimer laser annealing is investigated by ellipsometry, Raman spectra and SEM. The surface roughness is the measure of the crystal growth, and the increase of the roughness and the phase transition to polycrystalline-Si are detected by the Raman intensity. There is a good relation between the field effect mobility and the Raman intensity, but the grain size is out of proportion to the mobility. When the laser intensity exceeds the certain value, the a-Si film shows the ablation effect and It is seen that the incubation period is necessary to start the crystal growth. The incubated films become the poly-Si with high mobility and some large grain size.

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Inverted staggered poly-Si TFTs are fabricated by XeCl eximer laser annealing of plasma enhanced chemical vapor deposition a-Si:H films. The semiconductor layer of poly-Si TFTs is a multilayer of poly-Si and a-Si:H films. The channel direct contact structure improves the electrical characteristics resulting in mobility of 20 cm^2/V・s. The maximum process temperature, carried out below 300℃, is compatible with conventional a-Si:H TFT process. The 2.3-inch a-Si:H TFT LCD with a switch matrix of poly-Si TFTs has good performance and reduces the number of signal driver ICs by half.

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Bottom-gate poly-Si TFTs have heen successfully fabricated on a hard glass substrate using XeCl excimer laser annealing and non-mass-separated ion doping techniques. We used an a-Si:H film doposited by plasma enhanced chemical vapor deposition (PECVD) on SiN_× as a precursor film. The bottun-gate structure might allow us to use as many conventional a-Si TFT fabrication prccess as possible to realize poly-Si TFTs. By using excimer laser aunealing and ion doping , we have obtained excellent TFTs ,the field effect mobility of 200 cm^2/V・s. Also we have demonstrated the threshold voltage control method using a chaunel doping technique.

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A polysilicon thin film transistor scanning circuit immune to both open and short defects without circuit repair, has been developed for large-area active matrix liquid crystal displays. The scanner consists of regular and spare delay circuits, error-correcting circuits, transfer switches, exchange switches, and output buffers. The error correction does not impair circuit operation speed. Expected yield of a 1035-stage scanning circuit is increased twice to six-times.

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Characteristics were investigated for short channel a-Si TFTs. Since their parasitic resistance has been reduced by selective excimer-laser crystallization of the source and drain Si regions, the mobility decreased only slowly with the gate length from about 0.63cm^2/Vs for the 15μm-long TFT to about 0.42 cm^2/Vs for the 0.5μm-long TFT. Both the sub-threshold voltage swing and threshold voltage depended slightly on the gate length.

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Portraits of a laser-light reconstruction type have been produced based on holographic stereograms (HSs). Original image data of 256 × 256 pixels are taken by rotating a CCD camera around a human subject. To synthesize the portrait HS. 100-frame image data are recorded on a holographic film using a liquid crystal television panel as a spatial light modulator. In image reconstruction, virtual images which have a good parallax effect are observed by means of laser-light illumination. In order to eliminate flicker of the reconstructed image. the rotation angle of the CCD camera around the human subject must be set optimally.

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The fabrication and charactarization of an improved channel waveguide switch are reported. Nematic liquid crystals have large optical anisotropy and electrically controlled molecular alignment. Therefore we have made a channel waveguide using a two types of nematic liquid crystal cladding layer ; with and without a pair of eletrodes. The propagating modes in the waveguide was switched to the cladding by applying a voltage to the liquid crystal layer. Experimental results have demonstrasted contrast as high as 1430:1.

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By adding a uniaxial retardation film and using a chloric LC mixture, we improved the performance of polymer-dispersed LCDs with crossed Nicols (PDN-LCDs). We obtained a wide viewing angle (contrast ratio > 5) of more than 60° for the whole azimuth direction. In the horizontal and vertical viewing azimuth, contarast ratio was over 30 even at an inclination viewing angle of 60°.

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A high brightness LCD rear projector for HDTV has been developed. To achieve higher brightness, LCD panel of 50 % aperture ratio and F-number 5.6 high aperture projection lens have been developed. Moreover, new transmission type polarizing screen with moire pattern suppression effect, which is composed of polarizing sheet, fresnel lens and lenticular lens, has been also developed. By using these techniques, 450 cd/m^2 high brightness and more than 250 contrast ratio have been realized.

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A reflection-mode spatial light modulator consisting of a polymer-dispersed liquid crystal,a Bi_<12>SiO_<20> crystal, a dielectric mirror, an a-SiGeC:H light absorber, and antireflection films,has been developed for a large screen projection display. The device has good features, such as high extinction ratio (over 125:1) and high amplification factor(over 10^4). High luminous flux over 1500 lumens has been projected on a screen by using a Schlieren system incorporating the SLM and an 1kW Xe lamp for a readout light source.

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