Fermi level effect on compositional disordering of AlAs/GaAs superlattice

The Fermi level effect on impurity-induced compositional disordering of the AIAs/GaAs superlattice has been investigated by studying the disordering at the surface. It is shown that the Si-induced disordering is suppressed at the surface and the thickness of the suppressed layer depends on the Si concentration; that is, the superllatice with the larger Si concentration has the thinner suppressed layer. These results indicate that the surface suppression effect originates from the surface depletion layer where the Fermi level is pinned near the midgap, and that the intermixing is explained by the Fermi level effect.