Cr profiles in semi-insulating GaAs after annealing with and without SiO2 encapsulants in a H2-As4 atmosphere

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.