RHEED-BASED MEASUREMENTS OF ATOMIC SEGREGATION AT GAAS/ALAS INTERFACES

We have developed a simple method, based on the observation of transitions between surface reconstructions, allowing a direct in-situ measurement of Ga/Al atomic exchange, an effect known to occur when AlAs is grown on top of GaAs. We use it to demonstrate that this segregation, which results in interface broadening and weak lateral modulation in 2D or 1D quantum structures, depends strongly, at a fixed substrate temperature, on the choice of the growth conditions.