Signal readout in a-Si:H pixel detectors

A switch consisting of two a-Si:H p-i-n diodes was studied to read out signals from pixels for the imaging of X-ray or gamma ray distributions. A charge storage time of 20 ms and a readout time of 0.7 mu s were achieved. For the detection of single ionizing particles, polysilicon thin-film-transistor amplifiers can be integrated to amplify the small signals at the pixel level before readout. Prototype polysilicon TFT amplifiers were designed and fabricated. The measured gain-bandwidth product was approximately 300 MHz, and the input equivalent noise charge was approximately 1000 electrons for a 1- mu s shaping time.<
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