Electric Field Enhancement of Dark Current Generation in Detectors

ABSTRACTThe performance of detectors and sensors is degraded by dark current generation, which is due to defects and impurities in the materials. Electric fields enhance the generation from the resulting deep levels. When the electric field is in the mid-105 V/cm range, the present work finds enhancements of the order of 100 or more for iron and gold in silicon. The activation energy of the generation rate as a function of temperature is seen to decrease when the electric field increases. Many detectors have pixels that form a charge packet before the detectors are read out. Since the presence of charge decreases the electric field, the electric field enhancement varies with time. This is modeled for iron in silicon with an illustrative charge versus electric field relation. The resulting activation energy is found to be barely affected.