One Alternative Process to Vapor Pressure Control for the Bulk Crystal Growth of GaAs

In this work, aiming at improvement of growth processes for the bulk GaAs single crystals, efforts have been made first in investigate thermodynamic properties of the Ga and As system and second to suggest that bulk GaAs crystals could be grown in principle with the single temperature zone only by determining the excess arsenic charge as a function of growth conditions. During crystal growth, this will be evaporized inside the growth chamber to induce the required inner pressure, instead of aesenic vapor pressure in the double temperature zone method, so as to be in equilibrium with the method, growth experiments have been prepared and carried out for dopes and undoped GaAs crystals with the newly built Bridgman system which was designed according to this principle. To compare the results to those of the double temperature zone method, the same numbers of GaAs crystals have been grown with both processes and all of them were characterized in single crystallinity, lattice defects and electrical properties. Especially, the relationship between growth conditions and crystal quality was discussed from the viewpoint of growth peculiarities with this method.