Distribution Coefficient of Germanium in Gallium Arsenide Crystals Grown from Gallium Solutions

Abstract

Gallium arsenide crystals doped with germanium were grown from gallium solutions at 900°–875°C. The Ge concentration in the liquid was varied from 0.004 to 56 at.%, and the Ge concentration in the GaAs crystals determined using radiotracer and other techniques. The Ge concentration in the solid varied linearly with increasing Ge concentration in the liquid up to 5 at.% and kGe = (Ges)/(Gel)=0.0083±0.001. Above 5-at.% Ge in the growth solution, kGe increased. At low doping levels Ge acts predominantly as a simple acceptor substituting on arsenic sites. At high doping levels, in the extrinsic range, the Ge concentration in the solid is considerably greater than the free carrier concentration. The form in which the excess Ge exists is not known.