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Al films were grown by chemical vapor deposition at 400, 550, and 700 °C on GaAs(100) substrates using the molecular precursor dimethylethylamine alane. The film morphology and composition were studied in situ by reflection high-energy electron diffraction and Auger electron spectroscopy, and ex situ by atomic force microscopy and scanning electron microscopy. Chlorine (at 400 °C) and C and N (at 550 and 700 °C) at or below the percent level were found to be the major contaminants of the deposited films. Systematic studies for deposition at 400 °C established that the film microstructure evolves via the growth and coalescence of three-dimensional faceted islands with (100)Al∥(100)GaAs or (110)Al∥(100)GaAs preferential orientation. Coalescence of such crystallites was observed only for equivalent coverages of Al above 150 nm. Comparison with the microstructure of Al films obtained by evaporation suggests that in the temperature range examined the evolution of film morphology during chemical vapor deposition from dimethylethylamine alane was mainly determined by surface diffusion of isolated adsorbed Al atoms.

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Two methods of analyzing particles were interfaced to a low pressure chemical vapor deposition reactor used to deposit Al films from the liquid precursor dimethylethylamine alane. A laser light scattering particle counter was used to monitor particles (≳200 nm) in real time and established that the appearance of particles corresponded to the flow of precursor into the reactor. A particle impaction system was used to collect particles (≳20 nm) for analysis using analytical transmission electron microscopy and electron diffraction. Typical sizes of the Al particles were in the range 20–1000 nm. Purposely introducing trace amounts of H2O, CO, and O2 into the reactor during the flow of the precursor caused an increase in the number of particles. Our results suggested that Al particle formation was induced by impurities in the gas phase (particularly H2O) although competing mechanisms could not be ruled out.