Journal of Crystal Growth, Vol.260, No.1-2, 148-158, 2004
Improvement in crystalline quality of Cd1-xZnxTe(x=4%) crystals grown in graphite crucible
In this paper, we report improvement in the crystalline quality of CdZnTe (Zn = 4%) crystals, with respect to etch pit density and full-width half-maximum (FWHM) of the X-ray rocking curve, grown in graphite crucible as compared to crystals grown in carbon-coated quartz ampoule. Uniform dislocation density distribution of the order of 2-3 x 10(4) cm(-2) with no cellular structure and improvement in FWHM value (18-30 arcsec) with reduced splitting of peaks in X-ray rocking curves have been observed in the complete cadmium zinc telluride (CZT) wafers (30 mm x 50 mm). We have used a larger X-ray beam (10 mm x I mm) to study the crystalline quality of the complete CZT ingot. The effect of variation of beam size on X-ray rocking curve and its FWHM value indicates that the use of large beam size gives the true assessment of the spatial crystalline perfection of the grown CZT crystals. Although improvement in terms of crystalline perfection has been achieved in CZT material, the fall in optical transmission in the longer wave length spectral region and measured electrical properties in the annealed CZT samples point towards the incorporation of impurities in CZT during growth from the graphite crucible. Our results clearly indicate that overall improvement in the quality of CZT crystal is achievable with the use of ultra-high-purity graphite as the crucible. (C) 2003 Elsevier B.V. All rights reserved.