Chromium redistribution during thermal annealing of semi-insulating GaAs as a function of encapsulant and implant fluence

Chromium depth distributions have been measured in semi-insulating GaAs substrates that were thermally annealed (840 °C, 20 min) under both capless and SiO2-encapsulated conditions, with and without the presence of sulfur implants of several fluences. It is clearly shown that the chromium redistribution is not strongly influenced by the encapsulant but depends on the background chromium level and the implantation-induced damage. For sulfur implant fluences below ∼1013 cm−2, the chromium redistribution is similar to that in an annealed, unimplanted substrate.