Single layers of AlGaAs and quantum wells of GaAs/AlGaAs have been grown from the adduct trimethylamine alane (NMe 3·AlH 3), trimethylgallium (TMG) and arsine (AsH 3) using atmospheric pressure MOVPE. The growth is characterised by rapid darkening of the reactor due to a homogeneous side reaction. Low temperature photoluminescence data from the alloy Al 0.33Ga 0.67As shows that there is no reduction in the residual carbon contamination compared to a similar layer deposited from trimethylaluminium, TMG and AsH 3. The trend in electrical properties indicates an increasing acceptor concentration arising from the high purity TMG source. We have proposed that methyl groups from TMG are the precursors to the observed carbon contamination in NMe 3·AlH 3 grown AlGaAs.