Hall effect characterization of silicon activation and segregation in planar doped GaAs–AlAs superlattices

We have analyzed Hall data in GaAs–AlAs superlattices grown by molecular beam epitaxy. All samples had a very short period (3.7 nm) and were planar doped with silicon at a sheet density of 3.3×1010 cm−2 per plane. Silicon was introduced selectively either in the GaAs layers, in the AlAs layers, or at the interface. The silicon electrical activation did not depend on the doping plane location. Conversely, the thermal activation energy of the Hall carrier concentration was found to depend strongly on the doping plane location. From our experimental results, we estimate the silicon segregation length to be lower than 1.5 nm at a growth temperature of 550 °C.