Reverse bias currents in amorphous silicon nip sensors

Measurements are presented of the reverse bias currents in hydrogenated amorphous silicon nip diode sensors with sizes characteristic of those used in two dimensional sensor arrays. Several plates of sensors from different depositions were examined. The sensor currents have a common low-voltage characteristic due to 'central' leakage currents which scale with the sensor's area. At larger voltages sensors from different depositions exhibit a highly variable excess current which scales with peripheral length. We describe transient charge measurements for distinguishing currents originating from electron/hole generation currents and from injection at the n/i and i/p interfaces. It is concluded that the central currents are dominated by generation, and the peripheral currents by injection.