Development of hydrogenated amorphous silicon sensors for diagnostic X-ray imaging

Signal measurements with diagnostic-quality X-rays have been performed on photosensitive diodes fabricated from hydrogenated amorphous silicon. Such diodes exhibit high light collection and conversion efficiency and excellent radiation damage resistance and thus are candidates for X-ray imaging. Results of an examination of the linearity of the output signal with respect to X-ray exposure rate and of the signal size normalized to exposure rate are reported for various X-ray energies and phosphor screens. The leakage current was small in magnitude relative to the signal current, and the signal current displayed linearity over a large range of exposure rates. Such photodiodes are being incorporated in two-dimensional arrays of addressable sensors for real-time medical imaging.<
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