Tetsuo Iwaki

Probing the Crystallinity of Evaporated Silicon Films by Raman Scattering

Changes in the Raman spectra of evaporated a-Si films resulting from thermal annealing are reported in terms of the peak frequency and linewidth of a TO-like mode and the volume fraction of crystallinity ρ, where ρ is determined from the integrated intensities of resolved modes corresponding to a crystalline component and an amorphous-like component. The peak frequency and the linewidth show abrupt changes as the annealing temperature Ta rises, while ρ varies slowly with Ta, indicating a continuous crystallization with a constant rate, from Ta <400^°C. Moreover, the activation energy of the crystallization can be calculated by fitting ρ to the Avrami formula and is found to be the activation energy for viscous flow (0.35 eV). The crystalline TO mode of the highly-crystallized film is also compared to the results of the theoretical calculation reported by Richter et al.

An Architecture Of A High Speed Reed-Solomon Decoder

The authors propose an architecture for an error correction circuit suitable for high-rate data decoding of the Reed-Solomon code. It features a multiple-error correction capability of 4 errors or 8 erasures. The operational steps for multiple-error decoding are reduced by a 4-stage pipeline and a superscalar processor of a Galois field. The experimental circuits 16 Mbyte/s rate of data decoding is sufficient for compressed video signals of high-definition as well as those of standard-definition TVs. >

Turbo Decoding with Run Length Limited Code for Optical Storage

A new turbo decoding method with a run length limited (RLL) code for optical storage is proposed. The system entails a trellis code that joins the RLL code, the non-return-to-zero inverse (NRZI) conversion, and the partial response (PR) channel as the inner code. The inner a posteriori probability (APP) decoder is able to utilize the extrinsic information fed back from the output of the outer decoder. A turbo-coded (1, 7)RLL-constrained PR2 channel was simulated. The full, partial, and serial turbo decoding systems with the inner APP decoder achieved coding gains of 4.7 dB, 4.3 dB, and 3.3 dB, respectively, over the uncoded (1, 7)RLL-constrained PR2 channel at a bit error rate (BER) of 10-5. The full and partial turbos were also improved by 1.2 dB and 0.8 dB, respectively, over the partial turbo with the RLL soft-input soft-output (SISO) decoder at a BER of 10-5.

Raman Study of Silicon Small Particles

The particle-size dependence of Raman spectra of gas-evaporated silicon small particles, whose size distribution is well described by a log-normal distribution function, is reported in connection with their electron diffraction patterns. Although a diamond structure is confirmed by the Debye-Scherrer rings for the samples with an average particle size from 70 to 220 A, the Raman spectra are rather complex; the spectra are resolved into a new surface mode and three known modes (LA, TO and allowed-TO ones) in a range of 250 to 600 cm -1 . A disadvantage of the present theoretical studies relating to the finite-size effects of microcrystalline silicon is pointed out.

Small, prototype deck mechanism for a 1/4-in-tape digital camcorder

The authors have developed a small digital camcorder deck mechanism with a tape loading and transport mechanism suitable for very thin, metal-evaporated, 1/4-in tape. The stability of the deck mechanism is excellent; track linearity is >

Micromachined Silicon Submount for Optical Communication Devices

In this paper, we report the development of a new surface mount structure for optical communication devices using micro-electro-mechanical system (MEMS) technologies. We have designed and fabricated a silicon submount by wet anisotropic micromachining techniques. We have surveyed the main design parameters of this submount as an example against optical and thermal effects by computer simulations and experiments. We have mounted a light-emitting diode (LED) for plastic optical fiber (POF)-based optical communication systems on the silicon submount and evaluated the optical and thermal properties of this submount, indicating that the radiation half width at full maximum (HWFM) angle of the LED decreased from 60 to 40°. Additionally, we have observed a 60% reduction in the thermal resistance of the LED while keeping its thermal reliability.

Raman Study of Thermal- and Laser- Annealed Silicon Small Particle

Experiments are reported on the effect of thermal- and c.w.-laser-annealing on the Raman spectra of the silicon small particles prepared by gas-evaporation technique. The results are preliminarily interpreted in connection with the simple model calculation given by Richter et al. and the previous experiments for silicon films. It is suggested that in thermal annealing the Raman intensity near 520 cm-1 depends on the increase of grain size of silicon particles.

Solid State Imaging Techniques. Improvement of Image of Bayer Arrangement CCD using Image-shift.

We have developed a high-resolution color still camera by applying an image-shift of one pixel pitch displacement in the horizontal direction to a color still camera using a Bayer arrangement CCD. This two-positional imaging enables a simplified image-shift mechanism and high-speed imaging. We improved the resolution and suppressed chromatic moire by using a new chromatic moire suppression process that makes use of the correlation between RGB channels. We also eliminated the difference in light quantity between two images using a simple 1-dimensional lowpass filter in the horizontal direction. As a result, we have developed a digital still camera loaded with an image-shift mechanism that can be put to practical use. Our camera has higher resolution than a conventional camera using a Bayer arrangement CCD.

A Small Prototype Deck Mechanism for 1/4 Inch Digital Camcorder

Authors have developed a small digital camcorder deckmechunism for 1/4 inch widths tape. In this paper, the tape loading and transport mechanism suitable for very thin ME tape, the technology to suppress the noise caused by high speed drum rotation, and the wide band electromagnetic system are described.