Development of Planar P-type Point Contact Germanium Detectors for Low-Mass Dark Matter Searches

TL;DR

This paper reports the development and analysis of planar P-type point contact germanium detectors designed to detect low-energy signals for low-mass dark matter searches, emphasizing high electric field generation for internal charge amplification.

Contribution

It introduces a new planar point contact germanium detector design and demonstrates its capability to achieve the high electric fields needed for low-energy ionization detection.

Findings

Successfully developed a planar P-type point contact germanium detector.

Calculated electric field distribution confirms feasibility of internal charge amplification.

Demonstrated the detector's potential for low-mass dark matter detection.

Abstract

The detection of low-energy deposition in the range of sub-eV through ionization using germanium (Ge) with a bandgap of $\sim$0.7 eV requires internal amplification of charge signal. This can be achieved through high electric field which accelerates charge carriers to generate more charge carriers. The minimum electric field required to generate internal charge amplification is derived for different temperatures. A point contact Ge detector provides extremely high electric field in proximity to the point contact. We show the development of a planar point contact detector and its performance. The field distribution is calculated for this planar point contact detector. We demonstrate the required electric field can be achieved with a point contact detector.