New impurity-induced defect in heavily zinc-doped GaAs grown by liquid phase epitaxy

The electrical and photoluminescence properties of heavily doped GaAs:Zn(100) layers grown by liquid phase epitaxy from gallium and bismuth solutions at various temperatures have been studied. It is shown that a new line at 1.35 eV appears in low-temperature photoluminescence spectra of the layers doped at a level over 10(19) cm(-3). It is found that this line is associated with a novel defect. The concentration of defects increases with the doping level proportionally to the concentration of free holes to the power 5.35 +/- 0.1. The exponent is independent of the growth solution used (gallium or bismuth) and growth temperature. It has been found that the defect is a neutral complex consisting of native point defects of GaAs-an antisite defect of gallium in an arsenic site and two arsenic vacancies.