Characterization of Short-Wavelength-Selective a-Si:H MSM Photoconductors for Large-Area Digital-Imaging Applications
Photoconductor-type photodetectors are attractive as sensors due to their compatibility with thin-film-transistor (TFT) fabrication processes. Since they exhibit photogain, photoconductor detectors have better or comparable responsivity and quantum efficiency (QE) compared to p-i-n photodiodes. In this paper, the operation of metal-semiconductor-metal photoconductor-based photodetectors using aluminum electrodes and thin hydrogenated amorphous-silicon (a-Si) films is investigated. The experimental results of photocurrent measurements, as well as the responsivity and QE for different a-Si film thicknesses, bias voltages, and electrode gaps, are presented. Integration with TFT fabrication and its application in large-area digital imaging are discussed.
Light controlled oscillators; pixel architecture for large area linear digital imaging using amorphous silicon
The theory of operation and experimental results of a light controlled thin film transistor (TFT) oscillator circuits in amorphous silicon (a-Si) technology are presented. The circuit consists of a three-stage ring oscillator made of a top-gate TFT as driver and a photoconductor detector as the load for each stage, all fabricated in-house using a four mask top-gate process. Measurements indicate linear operation of the circuit up to 160 kHz output frequency with a sensitivity of 13.8 kHz/muW optical power at a biasing voltage of 25 V.
Amorphous silicon technology
The growth methods discussed in this volume include both regular and remote plasma enhanced chemical vapor deposition (PECVD), catalytic CVD (CTLCVD), atmospheric pressure CVD (APCVD), very high frequency plasma CVD (VHCVD) and magnetron sputtering. Some of the papers discuss the use of disilane to increase growth rates. The general questions of the kinetics of film growth is an important topic of discussion in this volume. Several mechanisms for monitoring film growth and lasma diagnostics are also topics of discussion.