Diffusion of be and mn during damage recovery of ion implanted GaAs

In this paper, implants of Be, Cd, Si and Se into semi-insulating GaAs as well as the fast diffusion of substrate impurities such as Mn were investigated to establish the profile parameters needed for device applications. Chemical and electrical depth profiles derived from secondary ion mass spectrometry and capacitance-voltage measurements indicate that both Be and Mn diffuse by the donor interstitial-acceptor substitutional mechanism. These conclusions are derived from chemical profiles of Mn in samples implanted with high and low mass donors, Si and Se and light and heavy mass acceptors, Be and Cd. Purity and impurity concentrations in the Be implanted GaAs had marked effects on its post-anneal distribution. A primary factor which influences these profiles is the extent of the host atom damage and the stoichiometric disturbances introduced during the ion implantation process. During the electrical activation of implants by capless controlled atmosphere annealing using AsH₃ in H₂, rapidly diffusing impurities such as Mn can be used to trace the changes in depth of the host atom points defects. The associated diffusions under highly non-equilibrium states are discussed. Our model incorporates the effects of relative damage due to the implant, the effect of Fermi energy on impurity migration and the effect of the arsine overpressure and anneal temperature on the diffusion profiles.