INSITU DEPOSITION OF AU ON PLASMA-PREPARED GAAS SUBSTRATES

In situ deposition of single crystal epitaxial and textured polycrystalline gold films on plasma-cleaned or plasma-etched GaAs substrates is accomplished in an ultrahigh vacuum integrated processing facility. Au/GaAs samples are characterized using reflection high energy electron diffraction, Auger electron spectroscopy, and ion channeling. Au crystallinity in films deposited at 100-degrees-C is shown to strongly depend on the GaAs surface cleanliness after plasma processing. Heating the substrate to 250-degrees-C after plasma processing subsequently yields epitaxial Au films; omitting the heating procedure results in polycrystalline Au films. The substrate thermal treatment removes residual physisorbed gas molecules and reaction products from the GaAs surface. Epitaxial Au films contain significantly less Ga and As on the free surface of Au than polycrystalline films, and no interaction between epitaxial Au and GaAs is observed.