Vapor Phase Equilibria for the Systems: GaAs-GaI[sub x]-As[sub y] and Ga-GaI[sub x]

Analysis of pressure measurements has led to the determination of the vapor species resulting from the reaction of with I . The reaction determined from the analysis is in the range 560°–850°C. The equilibrium constant is given by the equation, . The enthalpy calculated for the reaction is 54.1 kcal/mole of . A similar analysis for the system resulted in the determination of the reaction in the range 420°–650°C. The equilibrium constant for this reaction is given by . The enthalpy for the reaction is 25.2 kcal/mole of Ga. By combining the two equilibria in the region of overlapping temperatures, the arsenic pressures in equilibrium with along the three‐phase line are obtained. In the range 560°–640°C the predominant reaction is . The enthalpy calculated for this reaction is 44.4 kcal/mole of . The dissociation pressures are in good agreement with extrapolations from two previous measurements made at higher temperatures.