Role of temperature oscillation in growth of large-grain CdZnTe single crystal by traveling heater method

TL;DR

This study introduces a novel temperature oscillation technique during the traveling heater method to suppress nucleation, enabling growth of large, high-quality CdZnTe single crystals suitable for detector applications.

Contribution

The paper demonstrates a new approach using temperature oscillations to control nucleation and grow large, high-quality CdZnTe single crystals with improved properties.

Findings

Successful growth of 20 mm diameter, 60 mm length crystals

Crystals exhibited high resistivity (~10^9 Ohm-cm) and small Te inclusions

Achieved detector-grade crystals with 4.5% energy resolution at 662 keV

Abstract

Self-nucleation in CdZnTe crystal growth remains a significant challenge, despite numerous attempts to achieve large-grain single crystals by restricting multi-nucleation during growth process using the traveling heater method. In this study, we present a novel approach to achieve large-grain CdZnTe single crystals by introducing temperature oscillations above the crystallization temperature during the growth process. This method effectively suppresses secondary nucleation and promotes the preferential selection of a single grain during early stage of growth as well as along the growth axis, by reducing multi-nucleation. By adjusting the amplitude and the number of temperature oscillations, we have successfully grown CdZnTe single crystals with dimensions of 20 mm in diameter and 60 mm in length. The resulting crystals exhibited excellent compositional homogeneity, with a nearly constant resistivity of ~ 10^9 Ohm-cm and Te inclusions smaller than 15 microns along the growth axis. Additionally, the crystal elements were of detector grade achieving an energy resolution of 4.5% for gamma radiation at 662 keV from a 137Cs source in a quasi-hemispherical geometry. This study highlights the critical role of temperature oscillations in controlling secondary nucleation and promoting the formation of large-grain single crystals.