Vapor pressures of the adducts formed during AlGaN organometallic vapor-phase epitaxy
We have measured the vapor pressure of the adducts of trimethylgallium (TMGa) and trimethylaluminum (TMAl) with ammonia near room temperature. The vapor pressures of the mixtures of the adducts were also measured and found to obey Raoult’s law. Both the gallium and aluminum adduct have a relatively low vapor pressure (410 mtorr and 74 mtorr, respectively, at 19°C), which places limits on the design and operation of AlGaN organometallic vapor-phase epitaxy (OMVPE) reactors. Adduct condensation may also be the explanation for numerous observations of powders and crystals inside OMVPE reactors.