Lateral conduction in structured amorphous silicon p+-i-n+ photodiodes

Two-dimensional amorphous silicon image sensor arrays are used for medical imaging and document scanning. Our high-resolution arrays use a continuous p(+)-i-n(+) photodiode sensor layer with patterned n(+)-doped contacts. We report measurements of the lateral conduction phenomena that can arise with this sensor layer design, particularly when different illumination conditions give a non-zero voltage between adjacent pixels. The lateral conduction is affected by the sensor bias and by the potential of buried metal contacts. We also investigate the photocurrent collection properties by shining a focused laser beam in the gap between sensors. Collection at the contacts is evaluated, together with losses at the center of the gap. The effect of sensor bias on the collection is evaluated as well. (C) 2000 Elsevier Science B.V. ALI rights reserved.