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-Be(+1)=0.17 exp(-3.39 eV/k(B)T) cm(2) s(-1), D-1=6.4X10(-5) exp(-1.28 ev/k(B)T) cm(2) s(-1), and C-l(*int)=4.7X10(28) exp(-3.25 eV/k(B)T) cm(-3). The role of nonequilibrium Ga point defects in the anomalous Be diffusion behavior is addressed. (C) 1995 American Institute of Physics.