# Single Electron-Hole Pair Sensitive Silicon Detector with Surface Event Rejection

## TL;DR

This paper presents a silicon detector capable of single electron-hole pair resolution at cryogenic temperatures, with surface event discrimination, improving detection accuracy for rare event searches.

## Contribution

The study introduces a silicon detector with high surface coverage that achieves single electron-hole pair sensitivity and effective surface event rejection at millikelvin temperatures.

## Key findings

- Achieved 3 eV baseline energy resolution.
- Demonstrated charge resolution of 0.06 electron-hole pairs.
- Identified charge leakage along side walls as cause of dark events.

## Abstract

We demonstrate single electron-hole pair resolution in a single-sided, contact-free 1 cm$^2$ by 1 mm thick Si crystal operated at 48 mK, with a baseline energy resolution of 3 eV. This crystal can be operated at voltages in excess of $\pm50$ V, resulting in a measured charge resolution of 0.06 electron-hole pairs. The high aluminum coverage ($\sim$70%) of this device allows for the discrimination of surface events and separation of events occurring near the center of the detector from those near the edge. We use this discrimination ability to show that non-quantized dark events seen in previous detectors of a similar design are likely dominated by charge leakage along the side wall of the device.