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.
An a-SiGe:H,F based thin film MSM high-speed photodetector
In this work we propose and show the initial results of the use of a-SiGe:H as the base material for the development of very fast photodetectors for operating at wavelengths up to 1.55 mum. The device is a thin film device on which a MSM structures was built to form the photodetector. The device was already tested under IR illumination of 940 and 106 nm of wavelength in photovoltaic mode by means of pulsed laser with a 10 nsec duration pulse. The dark current has been measured and is 2.4times10-8 A at a bias of 3 V. Because the compatibility of the fabrication process with the silicon technology, low dark current and low bias needed for operation, this device is proposed to be integrated with the CMOS circuitry to form the front end of a communication system totally build on silicon or as device for the future inter or intra chip communications
High-sensitivity planar Si-based MSM photodetector with very thin amorphous silicon-alloy quantum-well-like barrier layers
A high-sensitivity, low dark-current planar Si-based metal-semiconductor-metal photodetector (PD) has been successfully fabricated. Under a very weak 0.83-/spl mu/m incident light power (0.5 /spl mu/W) and a 4-V bias voltage, the device photocurrent-to-dark-current ratio (I/sub p//I/sub d/) could reach 10/sup 3/. Also, the average full-width at half-maximum and fall time of the device temporal response were 68.18 and 294.7 ps, respectively, as measured with a periodic 0.83-/spl mu/m 60-ps light pulse at a 10-V bias voltage. In contrast to the previously reported various Si-based PDs, this device exhibited significant improvements in sensitivity and temporal response due to the employed quantum-well-like amorphous silicon-alloy barrier layers.