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Deposition of gold, palladium, and gold-palladium alloys is obtained with the help of acidic electroless baths of low metal content. The baths are prepared by suitably mixing separate solutions containing the reductant (hydroxylamine hydrochloride) or one of the desired cations respectively, with suitable additives. The stability of the baths with time is good and their replenishment easy to realize. Provided that a suitable choice of mixture of the three solutions is made, they allow the fabrication of multilayered heterostructures which could be fruitfully used for ohmic contact preparation onto n-GaAs without any initial activation step. The deposition mechanism of gold and palladium and the effect of adding palladium to gold is discussed.

Mixed Pd-Sn colloidal systems are used to activate nonconductor surfaces for electroless metal deposition. The ways to prepare the colloidal solution (temperature, pH, reaction time) and the aging process have an effect on the size and the structure of the adsorbed Pd-Sn nuclei. The studies are supported by high resolution transmission electron microscopy observations, and selective area electron diffraction, energy dispersive x-ray spectroscopy, and Rutherford backscattering spectroscopy analyses.

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