Thin Al intralayers induce changes in the valence-band discontinuities for the Ge/ZnSe(110) and the Ge/CdS(101¯0) heterojunctions, but not for the Si/GaP(110) heterojunction. We studied the dependence of the changes on the intralayer thickness, and their correlation to the local chemical reactions. The changes saturate for intralayers thicknesses ∼(1/2 monolayer. For these thin intralayers, the Al is highly reacted with the anion of the compound semiconductor. The results indicate that the band lineup at heterojunction interfaces is affected by a Schottky-like term, as recently suggested by several theories. However, they also show that such a term does not imply the formation of a metallic Al phase.

• Received 18 April 1988

DOI:https://doi.org/10.1103/PhysRevB.38.10949