Composition–temperature–partial pressures data for Cd 0.8Zn 0.2Te by optical absorption measurements

Abstract

Known weights of Cd, Zn and Te were reacted in silica optical cells of known volume, and the partial pressures of Te 2 and Cd between 485 and 1160 °C were determined by measuring the optical density of the vapor in the ultra-violet to visible range. The composition of the condensed phase or phases was calculated from the original weights and the amount of material in the vapor phase. The corresponding composition–temperature–partial pressures, x Te – T – P Te 2 , data, including five Te-rich solidus points, were established. The solubility range for the Te-rich Cd 0.8Zn 0.2Te(s) is similar to that of CdTe(s) with x Te = 0.50005 at 809 °C and an estimated maximum solubility of x Te = 0.50012 at about 1000 °C. The partial pressures of Cd and Te 2 measured over the Cd 0.8Zn 0.2Te melt at 1140 °C were about 1.55 and 0.02 atm, respectively, and the corresponding Zn partial pressure was estimated to be 0.05 atm. It was recommended that a Cd reservoir maintained at 800–820 °C should be used during directional solidification of Cd 0.8Zn 0.2Te to prevent the preferential loss of Cd to the vapor phase.