Polycrystalline silicon

About: Polycrystalline silicon is a research topic. Over the lifetime, 19554 publications have been published within this topic receiving 198222 citations. The topic is also known as: polysilicon & poly-Si.

Crystallization Process of Polycrystalline Silicon by KrF Excimer Laser Annealing

Abstract: We have investigated the crystallization of a-Si films by means of pulsed KrF excimer laser annealing as a function of irradiation energy density (E L), using transmission electron microscopy (TEM), Raman scattering spectroscopy and secondary ion mass spectrometry (SIMS). The grain size increased gradually at 0.2–0.4 J/cm2, while a drastic enlargement of grains occurred with lateral growth at 0.6–0.8 J/cm2. The stress in the films decreased with a decrease in the thickness of the fine grain (FG) layer until the FG layer finally disappeared. We proposed a model in which a drastic enlargement of grains at high E L is controlled by the nucleation rate, the solidification velocity, and the nucleus density of initial growth. It was found that poly-Si films with large grains ( 0.5–0.9 µm), high purity of C ( ~3×1016 cm-3) and low stress were obtained in the high E L regime ( 0.6–0.8 J/cm2).

Method of fabricating thin film transistors for a liquid crystal display

Abstract: A method of fabricating a thin film transistor (TFT) for a liquid crystal display (LCD) device having a drive circuit and a pixel array formed on the same substrate. The method includes forming a polycrystalline silicon layer by growing silicon grains from an amorphous silicon layer using the technique of sequential lateral solidification so that the silicon grains are oriented in a first direction, forming an active layer by patterning the polycrystalline layer, the active layer defining channel directions of the TFTs which are inclined at a predetermined angle with respect to the first direction, and forming the TFTs on the active layer. The method enhances the uniformity of the physical characteristics of the TFTs formed on the substrate.

Optical properties of phosphorus‐doped polycrystalline silicon layers

Abstract: The index of refraction and the absorption coefficient of low‐pressure chemical vapor deposited polycrystalline silicon (poly Si) implanted with various doses of phosphorus were obtained by means of transmittance and reflectance measurements. The refractive index of poly Si is relatively insensitive to doping in the visible region of the spectrum and agrees quite well with published values for single‐crystal Si. The absorption coefficient of these films decreases with doping in the visible. Nevertheless, the absorption coefficient corresponding to the highest‐doped film (N≊3×1020/cm3) is almost twice the published values for lightly doped single‐crystal Si. In the infrared, the index of refraction decreases systematically and the absorption coefficient increases systematically with doping. This dependence of the optical parameters on doping is attributed to the presence of free carriers. A free‐carrier dispersion/absorption model is applied to the measured refractive index in the region 1.2–1.8 μm and to the reflectance measurements in the region 2.5–7.5 μm. The model gives carrier concentrations for the two types of measurements which differ by 50%. Possible explanations for this difference are discussed. The carrier concentrations and mobilities obtained from optical and Hall‐effect measurements are compared.

High liquidus viscosity glasses for flat panel displays

Abstract: This invention is related to glasses for use as substrates in flat panel display devices; more specifically, for use as substrates in LCDs which utilize polycrystalline silicon thin film transistors. The compositions for the inventive glasses are essentially free from alkali metal oxides and consist essentially, in mole percent, of SiO₂ 64-70 Y₂O₃ 0-5 Al₂O₃ 9.5-14 MgO 0-5 B₂O₃ 5-10 CaO 3-13 TiO₂ 0-5 SrO 0-5.5 Ta₂O₅ 0-5 BaO 2-7 Nb₂O₅ 0-5 MgO+CaO+SrO+BaO 10-20 .