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The chemical and electrical characteristics were measured of loo-keV Si+ -implanted GaAs at doses of(6-10) X 10 12 cm-2 after rapid thermal annealing (RTA) for times of 5-40 s at temperatures between 850 and 975°C. Optimal conditions were 5 s at 930°C in either Ar or Ar-H2 atmospheres. Purity of the gas ambient was critical at the higher temperatures. Surface degradation was minimal for face-to-face annealing, as compared to exposed Si0 2 encapsulated surfaces. Essentially identical electrical characteristics were obtained by the preferred RTA conditions as compared to 30-min conventional furnace annealing under optimum conditions at 850°C using the controlled atmosphere technique. The markedly different RTA annealing times with comparable electrical characteristics are attributed to the differences in the host lattice damage recovery resulting from heat transfer and the actual duration to reach the desired anneal temperature.

Velocities of propagation of high-frequency ultrasonic waves and the adiabatic elastic moduli for single-crystal gallium arsenide are reported. Data at 25°C were obtained in the range of 20–180 mc/sec. The elastic moduli based on a density of 5.307 g/cm3 in units of 1012 dynes/cm2 are c11 = 1.188±0.14%; c12 = 0.538±0.36%; c44 = 0.5940±0.14%.

No abstract

The redistribution of Cr in semi-insulating GaAs upon annealing at 860 °C can be greatly reduced by eliminating the use of a SiO2 encapsulant. The annealing schedule utilized a controlled atmosphere technique which insured the thermodynamic stability of the GaAs surfaces and had no tendency to getter Cr. The sample annealed with a SiO2 encapsulant showed a secondary-ion-mass-spectroscopy-measured minimum Cr concentration which was lower by a factor of 20–25 than the original, whereas the comparison of an annealed sample without the SiO2 cap had a minimum Cr concentration which was smaller by a factor of 2. The conversion near the surfaces of semi-insulating Cr-doped GaAs to moderately high-conductivity n type upon annealing can be minimized by using the above technique without an encapsulant.