INTERFACIAL REACTIONS IN THE IR GAAS SYSTEM

Interfacial reactions between iridium and gallium arsenide in both the thin-film and bulk forms have been investigated in the temperature range 400 to 1000 °C using transmission electron microscopy, energy dispersive x-ray analysis, and electron probe microanalysis. The diffusion path for Ir/GaAs has been determined to be Ir/IrGa/IrAs2 /GaAs and is consistent with the phase diagram between the initial stages of reaction (thin-film) and long-term annealing (bulk). In the thin film case where the Ir supply is limited, the final configuration is Ir3 Ga5/ IrAs2 /GaAs. The diffusion path and reaction morphology has been rationalized using the phase diagram, kinetic observations, and growth mechanisms observed during the reactions.