Pulsed supersonic molecular beam growth of AlN

Non-skimmed pulsed supersonic free jets of trimethylaluminum (TMA) and ammonia are used to grow thin films of AlN. The translational kinetic energy of the precursors used for growth trials is 130 meV for TMA and 160 and 500 meV for ammonia. Effects of varying each pulse rate, substrate temperature, and deposition time on film composition and growth rate are studied. The resulting films were nearly always oriented with the non-polar (10⋅0) plane parallel to the silicon substrate (001) plane or to the sapphire substrate basal plane. The measured lattice parameter ratio c/a is 1.594. Film growth only occurred in a narrow range of pulse rates. Films can be grown over the temperature range of 900–1200 K. An average growth rate of 0.115 μm/h is measured. AlN films could also be grown when the substrates were not directly in the beam path. The role of precursor flux on film growth is discussed. Additional post-deposition analysis includes Fourier transform infrared spectroscopy, reflectance spectroscopy, scanning electron microscopy, and Auger electron spectroscopy.