Characteristics of molecular beam epitaxy grown GaAs simultaneously doped with Si and Be

Simultaneous doping (codoping) of n- and p-type impurities in GaAs is investigated using Si and Be as n- and p-type dopants. In highly Si-doped GaAs layers, the electrical activation ratio of Si-donors is much less than unity because of the formation of compensating centers such as antisite Si (Si-As), Si-clusters and Ga vacancies (V-Ga) Although no enhancement is observed in the electrical activation, it is round that most of these compensating centers disappear as a result of codoping. The integrated photoluminescence intensity in the codoped GaAs layers is much higher than that in the solely Si-doped samples, indicating that simultaneous Si and Be doping decreases the concentration of nonradiative recombination centers created by high Si doping, without lowering the electron concentration.