# The impact of neutral impurity concentration on charge drift mobility in n-type germanium

## TL;DR

This study investigates how neutral impurity concentration affects charge drift mobility in high purity n-type germanium at 77K, highlighting the significance of neutral impurity scattering in electron mobility.

## Contribution

It provides a theoretical and experimental analysis of neutral impurity effects on charge mobility, including the derivation of neutral impurity distribution in crystals.

## Key findings

- Neutral impurity scattering significantly impacts charge mobility.
- Neutral impurity concentration varies radially in crystals.
- Mobility depends on neutral impurity levels.

## Abstract

The impact of neutral impurity scattering of electrons on the charge drift mobility in high purity n-type germanium crystals at 77 Kelvin is investigated. We calculated the contributions from ionized impurity scattering, lattice scattering, and neutral impurity scattering to the total charge drift mobility using theoretical models. The experimental data such as charge carrier concentration, mobility and resistivity are measured by Hall Effect system at 77 Kelvin. The neutral impurity concentration is derived from the Matthiessen's rule using the measured Hall mobility and ionized impurity concentration. The radial distribution of the neutral impurity concentration in the self-grown crystals is determined. Consequently, we demonstrated that neutral impurity scattering is a significant contribution to the charge drift mobility, which has a dependence on the concentration of neutral impurities in high purity n-type germanium crystal.