Czochralski growth of tellurium single crystals

Abstract

It has been found that tellurium single crystals, with typical dimensions of 2 cm diameter and 10 cm length, can be grown routinely by the Czochralski method with essentially a 100% yield under appropriate conditions. One of the most important of these is the avoidance of thermal shock at the start of the growth, which can be achieved by having a high background temperature with a slow approach of the seed to the melt surface prior to dipping. Using this procedure, single crystals boules have been grown in the c-direction at pulling rates from 0.8–3.4 cm/h, without obvious deterioration of the crystal quality, as evidenced by visual inspection and Laue X-ray diffraction. It was found that the ratio of the three larger faces of a c-grown crystal (hexagonal cross-section) to that of the three smaller ones was increased with increase of pull rate. High background temperature was also found to be beneficial during the main part of the growth process. Growth with the pull direction at right angles to the c-direction was also carried out, yielding flat-shaped crystals, in which again, the ratio of the long and short axes was found to increase with pull rate.