Optimizing the temperature gradient for CdZnTe crystal growth using the vertical Bridgman–Stockbarger method

Abstract

CdZnTe (CZT) is considered an ideal material for the growth of HgCdTe (MCT) epitaxial layers and nuclear detection devices. The crystal quality of CZT is the key factor in the MCT-based infrared plane array and the performance of nuclear devices. Herein, we report the growth of CZT by optimizing the temperature gradient vertical Bridgman–Stockbarger method. The crystalline character of the obtained CZT has been examined using optical microscopy, IR transmission microscopy, high-resolution X-ray diffraction, X-ray tomography (XRT), Fourier-transform infrared spectroscopy and glow discharge mass spectrometry. The etch pit dislocation density of the CZT sliced wafers (111)-B was less than 4.0 × 103 cm−2, the triangular shape inclusions in the CZT volume of the double-grinding wafers have a sparse distribution, and the size can be controlled to be less than 5 μm, the typical full-width at half-maximum of the Bragg diffraction peak was 17.4″. The XRT image of polished CZT wafers (111)-B showed a uniform structure without strain and defects. About 100 % of the CZT wafers showed transmittance >50 % at 20 µm and the detected impurities in the crystal were low, Li 4.9 ppb and Na 2.9 ppb, indicating the formation of high-quality CZT crystals. This work provides a scheme to improve the crystal quality of CZT for high-performance device applications.