Silicon-Induced Local Interface Dipole in Al/GaAs(001) Schottky Diodes

Al/Si/GaAs(001) diode structures grown by molecular beam epitaxy were examined as a function of the thickness of the Si interface layer and the intensity of the As or Al flux employed during Si deposition. We found that Schottky barriers as low as 0.3-0.4 eV (in the presence of a sufficiently high As flux) or as high as 1.0-1.1 eV (in the presence of a sufficiently high Al flux) can be established on n-type GaAs at Si coverages in the submonolayer to monolayer range. We therefore associate the tunability of the barrier height with a Si-induced local interface dipole.