P. Sellitto et al., EVIDENCE OF SILICON INTERDIFFUSION IN SELECTIVELY DOPED GAAS-ALAS SUPERLATTICES BY HALL MEASUREMENTS, Journal of applied physics, 74(12), 1993, pp. 7166-7172
Hall and photo-Hall measurements have been performed on GaAs-AlAs shor
t-period superlattices selectively doped with silicon. The dopant was
introduced selectively in either the GaAs or AlAs layers or at the int
erface. A superlattice doped uniformly in both layers was investigated
for comparison. The electrical properties were controlled by DX deep
donors lying in the gap of the superlattice. Hall data are interpreted
with a model taking into account the existence of two DX deep donors
and a shallow donor both related to the silicon impurity. It is found
that the silicon donor state in AlAs lies 60 meV below the silicon don
or state in GaAs. The ionization energies of the DX states in GaAs and
AlAs are computed to account for the experimental results. Interpreta
tion of Hall data in selectively doped samples needs to assume segrega
tion of silicon atoms during epitaxy.