Dependence of atomic diffusion in GaAs upon experimental design

摘要

The rate of impurity diffusion in GaAs depends upon thenconcentration of point defects such as vacancies and interstitials. Thenconcentration of those point defects is strongly affected by the regionnof the phase diagram corresponding to the chosen experimental design.nDifferent regions of phase diagrams are used to illustrate why nominallynsimilar experiments can lead to dramatically different results. When thenequilibrium point defect concentrations can be approached in a timenwhich is short compared to the anneal time, the measured diffusivitiesntend to be reproducible. However, when the point defect concentrationsnapproach their equilibrium values over times which are long compared tonthe anneal time, the measured diffusivities tend to be irreproduciblenand time dependent. Examples of “anomalous” diffusion arendiscussed and shown to be associated with fundamental differences innexperimental design that tend to bring the point defect concentrationntoward equilibrium in different regions of the phase diagram