Mg*/O* Ion Implantation in GaAs/GaAlAs Heterostructures

Mg⁺ and O⁺ ion implantations have been performed in GaAs/GaAlAs heterostructures for bipolar transistor applications in order to form an isolation layer in the collector region (with 0) and to contact the base layer (with Mg). Rapid thermal annealing with peak temperature up to 900°C has been employed to activate Mg. We show that the conditions to obtain compensation by oxygen are strongly dependant on the starting material. Moreover for low oxygen doses we have noted an evolution of the compensation with time. Finally we discuss the interaction between Mg and Be (dopant of the base).