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Transmission electron microscope studies of Sn/Au thin-film couples reveal complexities associated with the Kirkendall effect in thin films. The use of an offset film fabrication technique permitted the identification of two room-temperature interdiffusion mechanisms in Sn/Au: grain-boundary diffusion of Sn into Au, which causes film thinning, and bulk diffusion of Au into Sn, which results in the formation of microscopic Kirkendall voids. The ranges of importance of the two mechanisms were explored by varying the Sn and Au film thicknesses and the grain size. It is pointed out that interdiffusion studies in thin films required careful attention to relative film thicknesses, film geometry, and grain sizes in order to determine the fast-diffusing species and the operative diffusion mechanisms.

A new contact to p-InP is reported with beryllium as the acceptor. The contact consists of a thin layer of 3 wt.% Be in Au alloy and a Au overlay sequentially deposited by e-gun evaporation. Alloying at 420 °C yields Ohmic contacts with low specific contact resistance rc⩽8×10−5 Ω cm2 for InP with NA−ND ≲1×1018 cm−3. To minimize the tendency of InP for thermal dissociation, the alloying temperature can be reduced to 375 °C by adding a thin Pd layer at the semiconductor metallization interface. This is achieved at the expense of a slight increase in resistance.

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