Quasi-quantitative estimation of solidus curve on As-rich side of Ga-As system

Abstract

A quantitative investigation of the solidus curve on the As-rich side of the Ga-As system was done by estimating the amount of excess As in crystals grown from As-rich melts. Excess As atoms in a GaAs crystal are usually subjected to two forms: precipitation and dissolution. To obtain the solidus curve, it was assumed that the EL2 concentration gives the composition of the crystal when almost all the dissolved excess As form EL2. The maximum EL2 concentration was produced in crystals by a new thermal treatment that dissolves As precipitates and is assumed to change almost all the dissolved As into EL2. The maximum EL2 concentration showed a strong linear correlation with the melt composition. A solidus curve has been drawn that has a parabolic shape similar to the liquids curve. The congruent point is shifted from stoichiometry toward the As-rich side by an amount equivalent to an EL2 concentration of 10 16 cm -3.