Metallurgical and electrical properties of &bgr;‐phase PdAl Schottky metallizations onn‐GaAs after rapid thermal annealing for 20 s in the temperature range 500–1000 °C have been investigated using x‐ray diffraction, transmission electron microscopy, Auger depth profiling, film resistivity, and current–voltage measurement. The Al‐rich contacts were stable up to 900 °C whereas the Pd‐rich contacts were less stable. The thermal stability of &bgr;‐PdAl exhibited a sharp variation near the stoichiometric composition. The thermal stability of Pd‐rich contacts decreased with increasing Pd composition, and the interfacial reaction after high‐temperature annealing resulted in the formation of PdGa compound. The interface between Al‐rich PdAl film and GaAs substrate remained quite sharp even after 900 °C anneal. The variation of interfacial stability at high temperatures between &bgr;‐PdAl film and GaAs substrate is correlated to the compositional dependence of Al and Pd activities in PdAl within the &bgr;‐phase region. The Schottky barrier heights of Al‐rich PdAl contacts increased with annealing temperature. The barrier height enhancement in the annealed Al‐rich contacts can be attributed to the thin AlxGa1−xAs layer formed at the interface. ©1995 American Institute of Physics.