Thermophysical properties of telluride, mercury telluride, and mercury cadmium telluride melts

The objectives of this project were to develop a new, reliable method to accurately determine the thermophysical properties of molten semiconductors and to use this method to determine the thermophysical properties of II-VI semiconductor melts. The ternary Hg-Cd-Te melts are of interest due to the wide application of the single crystals in this system in the semiconductor industry. In order to fully understand the melt structures of Hg-Cd-Te melts related to their thermophysical properties, the thermophysical properties of the major single element component Te and the binary compound HgTe melts were determined as well. Three important thermophysical properties, namely density, electrical conductivity and viscosity, were studied in this project.; First, mercury was used to verify the newly developed transient torque method for simultaneously determining both the electrical conductivity and the viscosity of mercury. The measured electrical conductivity and viscosity of mercury were in good agreement with previously published data. Second, the transient torque method was used to determine the electrical conductivity and the viscosity of Te, HgTe, and II-VI semiconductor melts from the melting point or the liquidus temperature to higher temperatures. A pycnometric method in a transparent furnace was utilized to measure the density of the II-VI semiconductor melts from the melting point or the liquidus temperature to higher temperatures.; The results for the density, electrical conductivity and viscosity of Te, HgTe, and Hg1-xCdxTe melts showed good agreement with published data obtained using several methods. The thermophysical properties data determined in this study provide useful data for the database of the thermophysical properties of II-VI semiconductor melts at high temperatures. An observed maximum in the density of II-VI semiconductor melts at high temperatures, the calculated free activation energy of the viscous flow of II-VI semiconductor melts from kinematic viscosity data, and the empirical relationship between the kinematic viscosity and the density of Te, HgTe, and Hg1-x CdxTe melts could be used as indicators of the structural transitions in these melts. Observed anomalous changes in the thermophysical properties of the II-VI melts may also be used as indications of structural transitions in the melt.