DEWETTING AND STRUCTURAL QUALITY OF CdTe:Zn:V GROWN IN SPACE

The experiment STS95-Spacehab-AGHF1 has been devoted to the study of the dewetting phenomenon applied to the growth of CdTe:Zn:V. Two samples have been introduced in quartz ampoules and solidified directionally. However, one sample has been grown at a very high rate, due to untimely furnace shut-off. After the analysis of the experimental data, the growth rate and thermal gradient have been estimated. Metrology of the samples, surface roughness and microscopic analysis show that both space samples presented similar partial dewetting, with the conclusion that the growth rate is not involved in the phenomenon. The ground reference sample has shown a closer contact and moulding to the crucible wall. A special design of one ampoule prevented the establishment of any pressure difference between the hot and cold parts of one space sample, then demonstrating that such differences are not necessarily involved when dewetting occurs. The structural analysis is still under progress. The sample grown at high rate shows twins from the very beginning. The ground reference sample is polycrystalline from the beginning of the solidification. The space sample grown under nominal conditions is a single crystal on the first 11 mm, demonstrating that dewetting, even partial, is beneficial to the crystal structural quality.