Modeling the charge collection efficiency in the Li-diffused inactive layer of P-type high purity germanium detector

A model of the Li-diffused inactive layer in P-type high purity germanium detectors is built to describe the transportation of charge carriers and calculate the charge collection efficiency therein. The model is applied to calculate charge collection efficiency of a P-type point-contact germanium detector used in rare event physics experiments and validated in another P-type semi-planar germanium detector. The calculated charge collection efficiency curves are well consistent with measurements for both detectors. Effects of the Li doping processes on the charge collection efficiency are discussed based on the model. This model can be easily extended to other P-type germanium detectors, for instance, the P-type broad-energy Ge detector, and the P-type inverted-coaxial point-contact detector. •A model of the Li-diffused inactive layer in the P-type high purity germanium detector is built to calculate the charge collection efficiency.•The charge collection efficiencies of two P-type high purity germanium detectors are calculated. The results are in good agreement with measurements.•The effects of the lithium doping process on the charge collection efficiency in the inactive layer are discussed based on our model.