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.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)