Modeling the diffusion of grown-in Be in molecular beam epitaxy GaAs

The diffusion of Be in GaAs is studied in samples which are molecular beam epitaxy GaAs with grown-in Be. The Be diffusion profiles of samples annealed under various conditions are obtained using secondary ion mass spectrometry. SUPREM-IV.GS, a simulator for GaAs and Si processing technology, is used to compare the experimental results with our models and to extract parameters. The Be diffusion profiles show a kink feature and a time-dependent Be diffusivity which are successfully simulated. The intrinsic Be diffusivity, the Ga interstitial diffusivity, and the equilibrium concentration of Ga interstitials, all as a function of temperature, are obtained from this study: D+1Be=0.17 exp(−3.39 eV/kBT) cm2 s−1, DI=6.4×10−5 exp(−1.28 eV/kBT) cm2 s−1, and CI*int=4.7×1028 exp(−3.25 eV/kBT) cm−3. The role of nonequilibrium Ga point defects in the anomalous Be diffusion behavior is addressed.