DELTA-DOPING IN-DIFFUSION STUDIES

The delta-doping where the dopant is confined on the length-scale of the lattice constant provides perfectly ideal conditions to study the atomic transport processes. We have studied MBE-grown GaAs samples delta-doped with Si and Al layers. Long time diffusion anneals have been performed in the temperature range 550-800 degrees C. The distribution profiles are examined by SIMS-profiling. We obtain Si diffusion coefficients in good agreement with the other recent studies using different techniques (rapid thermal annealing, capacitance-voltage profiling, sandwiched diffusion source). This contrasts with the earlier measurements based on diffusion of implanted dopants which were much more widely spread. We conclude that the more accurate data allowed with the delta-doping show that the diffusion coefficient is an intrinsic parameter provided that the amount of dopant and the dislocation density are kept sufficiently small.