Evidence of isovalent impurities in GaAs grown by molecular-beam epitaxy

High-pressure, low-temperature photoluminescence spectra of Si-doped GaAs grown by molecular-beam epitaxy show well-defined features corresponding to nitrogen-bound exciton recombination, together with other isoelectronic center-bound excitonlike lines. Though N, when isolated, only influence weakly the GaAs electronic properties, we briefly discuss the consequences of its association with other impurities. It is suggested that complexes involving isovalent impurities may be responsible for part of the defect bound exciton luminescence, observed by several authors in molecular-beam-epitaxy–grown GaAs. The source of isovalent impurities is tentatively attributed to the high-temperature boron nitride crucibles.