Stoichiometric disturbances in ion implanted GaAs and redistribution of Cr during annealing

Using the Boltzmann transport equation, calculations were obtained predicting the zones of stoichiometric imbalance produced in GaAs after ion implantation at energies of 50, 100, and 300 keV. The recoiling Ga and As atoms were shown to produce a zone of interstitials at depths exceeding Rp . Secondary-ion mass spectrometry profiling indicated that Cr was rapidly redistributed into these regions at temperatures ⩽500 °C. Transmission electron microscopic analyses obtained on horizontally sectioned and vertical cross section samples indicated that the interstitials coalesced into small clustered sites (50–100 Å) and were responsible for the development of Cr gettering at depths ≳Rp .