Hisashi Koaizawa

Inverted Aluminum-Induced Layer Exchange Method for Thin Film Polycrystalline Silicon Solar Cells on Insulating Substrates

In order to achieve high efficiency thin film polycrystalline silicon (poly-Si) solar cells on insulating substrate, we have developed a novel crystallization method of amorphous silicon (a-Si), an inverted aluminum-induced layer exchange (inverted-ALILE) method, where a metallic aluminum layer remains between the crystallized p+-layer and a glass substrate to function a back contact in contrast to the conventional ALILE method. Crystallization process of a-Si during inverted-ALILE was observed in-situ by optical microscope. The crystallized film was analyzed using Raman measurement, X-ray photoelectron spectroscopy (XPS) and electron back scatter diffraction (EBSD). Those analyses indicated poly-Si thin film with large grain size and preferential orientation of (100). The prepared poly-Si layer was applied to thin film solar cell and we confirmed a significant improvement in series resistance as compared to a conventional ALILE method.

Polycrystalline silicon thin-film transistors on quartz fiber

We demonstrate the fabrication of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) on a thin quartz fiber for the first time. The poly-Si used in the active layer of the TFTs was prepared by excimer laser annealing of an amorphous Si thin film deposited on the fiber. Top-gated TFTs were fabricated on the fiber, and a field effect mobility of 10cm2∕Vs was obtained. The proposed TFTs on a thin quartz fiber, named fiber TFTs, have potential application in microelectronic devices using TFTs fabricated on one-dimensional substrates.

Development of flexible fiber-type poly-Si solar cell

In order to obtain low-cost, high-performance and flexible silicon solar cell, a novel poly-Si solar cell using glass fiber substrate has been developed. Two ways for preparing poly-Si film on glass fiber for very high deposition rate were studied; one is atmospheric thermal CVD and the other is microwave PECVD. The film prepared by atmospheric thermal CVD showed good crystallinity and high hole mobility of 200cm 2/Vs at a carrier concentration of 6e15cm-3, despite its high deposition rate. The solar cell was examined on SiO2 substrate, and cell efficiency by atmospheric thermal CVD was 1.35%. Novel microwave PECVD system specialized for glass fiber substrate was also developed, and poly-Si film could be deposited on the glass fiber substrate at a deposition rate of 1 mum/s

64.5L: Late-News Paper: Large Area Flexible Display of Fiber OLED

For the production of large area display, we have proposed a concept of “one-dimensional substrate” instead of the large sized glass plate. Each of TFT and OLED has fabricated on a glass fiber which consists of a column in the display. It has also pointed out that the production scheme called Reel-to-Reel (RtR) has been required, which is completely different from the conventional process. In this paper, we describe an alternative of the original, which uses ribbon fiber and confined RtR processes only to OLED. The TFT fiber should be replaced by Si chips. This would enable more rapid progress for the development of the one-dimensional technologies. In addition the technologies will be applied to lighting.

Fabrication of poly-Si films by continuous local thermal chemical vapor deposition on flexible quartz glass substrate

The continuous deposition of polycrystalline silicon film on quartz fiber by local thermal chemical deposition was investigated. High-speed deposition owing to high temperature and locality was examined using fixed and moving substrates. We confirmed the high-speed deposition of polycrystalline silicon and achieved a maximum speed of over 1μm∕s. Furthermore, we succeeded in a continuous deposition of polycrystalline thin silicon with a thickness of 50–100nm on a quartz fiber with low roughness and low impurity content. Thin film transistor with a mobility more than 3.7cm2∕Vs was achieved by using this film.