Preparation of high purity glasses based on germanium and gallium tellurides using chemical transport

Abstract

Thermodynamic modeling of Ga2Te3-Ga2O3-GaI3 and GeTe-GeO2-GeI4 systems are carried out by the method of minimizing thermodynamic potentials in the temperature range 200–900°C. The efficiency of chemical transport method for vacuum loading of gallium(III) telluride and its purification from oxygen impurities is shown theoretically and experimentally. The method for preparation of high purity glasses based on germanium and gallium tellurides is developed. The technique includes the synthesis of glassy Ga10Ge15Te75 alloy, its thermal decomposition with the release of tellurium and germanium(II) telluride, and the subsequent loading of nonvolatile gallium tellurides by chemical transport using gallium(III) iodide as a transporting agent. The advantages of the developed technique in comparison with those known in the literature are discussed. The sample of ultrapure Ga-Ge-Te glass with an oxygen impurity content chemically bound to germanium at a level of 1 ppb(wt) is prepared.