Crystal growth and detector performance of large size high-purity Ge crystals

TL;DR

This paper reports on the growth of large high-purity germanium crystals using the Czochralski method, analyzing their impurity distribution and dislocation density, and evaluates a detector's spectral performance showing excellent energy resolution.

Contribution

It introduces a successful method for growing large high-purity Ge crystals with low dislocation density and demonstrates their effectiveness as radiation detectors.

Findings

Dislocation density meets detector requirements

Impurity distributions are characterized

Detector achieves excellent energy resolution

Abstract

High-purity germanium crystals approximately 12 cm in diameter were grown in a hydrogen atmosphere using the Czochralski method. The dislocation density of the crystals was determined to be in the range of 2000 - 4200 cm-2, which meets a requirement for use as a radiation detector. The axial and radial distributions of impurities in the crystals were measured and are discussed. A planar detector was also fabricated from one of the crystals and then evaluated for electrical and spectral performance. Measurements of gamma-ray spectra from Cs-137 and Am-241 sources demonstrate that the detector has excellent energy resolution.