SCHOTTKY-BARRIER TUNING AT AL GAAS(100) JUNCTIONS/

Using an ab initio pseudopotential approach, we have investigated the electronic structure of ideal Al/GaAs(100) and Al/Ga1-xAlxAs(100) junc tions, and the change of the corresponding Schottky barrier height ver sus the alloy composition x and in the presence of ultrathin group-IV atom interlayers. We find large changes in the Schottky barrier height which agree well with the experimental data. In order to interpret th e observed trends we have analyzed the charge density response to chem ical substitutions near the junction. This allowed us to extend to met al/semiconductor interfaces a microscopic linear-response theory appro ach previously employed to interpret band-offset trends at semiconduct or heterojunctions. (C) 1996 American Vacuum Society.