Modeling of Be diffusion in gaas layers grown by MBE

Beryllium diffusion is modeled in order to simulate the Be depth profiles obtained by SIMS measurements on p/p(+) and p/p(+)/p GaAs structures which underwent rapid thermal annealing (RTA) experiments at 850 degreesC for 30 s. The simulation procedure, which has been previously used to simulate Be and Zn diffusion in GaAs and in other related compounds. is critically discussed. It is shown that usual assumptions do not allow to simulate measured Be profiles in p/p(+)/p structures and that a qualitative agreement between measured and simulated Be profiles can be achieved in both p/p(+) and p/p(+)/p structures by considering proper initial conditions.