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High-spin states in 99Rh are populated through a fusion evaporation reaction 16O+89Y. A comprehensive level scheme with four bands is made on the basis of coincidence studies and DCO ratios. Placements of several transitions are revised and, together with five new transitions detected in the experiment, two new bands are proposed. Two other bands populated in the previous work are confirmed. The configurations of the three quasiparticle band-head states of the new bands are suggested as ( pi (g92/)3) and ( pi (g92/)* nu (h112/)2).

It has been proposed that interdiffusion of Pt, Au, and GaAs constitutes one major source of instability in GaAs microwave devices with Pt/Au metallization. In order to determine the extent of interdiffusion of these materials, preparations of Pt/GaAs and Au/Pt/GaAs were heat treated over the range 250–500 °C, and chemical depth profiles were obtained by measuring the surface composition with Auger electron spectroscopy while ion milling. Platinum films were 125–9000 Å thick. When Pt/GaAs was heated in vacuum, the Pt-GaAs interaction initiated with a rapid migration of Ga into Pt and simultaneous formation of an As-rich layer at the Pt/GaAs interface. Gallium eventually traveled the entire thickness of even the 9000-Å Pt film while arsenic stopped abruptly at a distance ∼2/3 of the way into the Pt. Little or no Au was detected (<1 at.%) in the Pt or GaAs after extensive Pt/GaAs reaction in Au/Pt/GaAs. The reacted Pt film displayed a multilayered structure with each layer containing different amounts of Ga, As, and O. Pt/GaAs heated in air behaved similarly with two added features: a surface layer containing mostly Ga and O formed over the Pt, and oxygen diffused through the (reacted) Pt to form an oxygen-rich layer at the Pt/GaAs interface. Interdiffusion (during air anneal) was found to be reduced when the GaAs was oxidized prior to Pt deposition.