EFFECT OF HIGH HYDROSTATIC-PRESSURE ON PHASE-COMPOSITION AND MICROSTRUCTURE IN AU-28 AT PERCENT GE ALLOY GAAS CONTACTS/

Effects of external hydrostatic pressure up to 7 kbar on the Au-Ge bin ary phase diagram and on the arsenic sublimation are evaluated by ther modynamic calculations. Experimental observations in the eutectic Au-2 8 at. % Ge/GaAs contacts which were annealed at vacuum and in a 7 kbar argon gas, respectively, are taken as illustrative examples for the c omparison with the calculated results. It is concluded that pressures up to 7 kbar shift only slightly the phase boundaries in the Au-Ge pha se diagram that were obtained in standard conditions (1 atm) and a pur e argon gas with a pressure of 7 kbar acts as a good capsulation to pr event species As from sublimation. The measurements indicate that the film/GaAs interface and the film surface in the contacts annealed at 7 kbar are rich in Ge and are morphologically smooth. (C) 1994 American Institute of Physics.