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.
Fabrication and Characterization of Nickel Amorphous Silicon Metal-Semiconductor-Metal Photoconductors
Fabrication and electrical characterization of metal-semiconductor-metal (MSM) photodetectors using nickel and amorphous silicon is reported. Fabricated detectors exhibit dark currents in the order of 10-12 A, a dynamic range higher than 106, and responsivity of 0.12 A/W. Detector current changes linearly with applied bias voltage in the range of 0 to 30 V, and incident optical power density between 0 and 107 mW/cm2. It was found that with channel length of less than 25 mum, external quantum efficiency of more than 30% is achievable. Such detectors are particularly suitable for imaging applications with very large area pixels.
Modeling of chemical reactors—XXIX mixing-cell model for packed bed reactors. Steady state considerations. Problems of multiplicity
Abstract The axial heat and mass transfer in tubular catalytic reactors may be described by mixing-cell model and diffusion model as well. The diffusion description yields for a strong exothermic reaction and adiabatic conditions three steady state profiles, on the other hand the mixing-cell model gives rise to more than three steady states. A simple numerical and graphical analysis for mixing-cell model is presented.