Sources of donor impurities in undoped GaAs grown using arsine and trimethylgallium

Magnetophotoluminescence spectroscopy (MPL) has been used to ascertain the source of donor impurities in high-purity GaAs grown by atmospheric pressure metalorganic vapor deposition using arsine and trimethylgallium. A linear correlation between absolute MPL intensity and net carrier concentration for high-purity n-type epilayers over the concentration range 1×1014–2×1015 cm−3 provided an unambiguous method for identifying the source of donor impurities by comparing epilayers grown with different source batches. Batch-to-batch variations in the quality of films grown with eight different arsine cylinders were traced directly to the presence of varying amounts of a Ge-containing contaminant in the arsine.