Barrier height variation in Al/GaAs Schottky diodes with a thin silicon interfacial layer

Al/n-GaAs and Al/Si/n-GaAs structures with thin silicon interfacial layers were grown in situ by molecular beam epitaxy and their electrical characteristics were measured. Effective barrier heights between 0.30 and 1.04 eV were determined through I-V and C-V measurements in the Al/Si/n-GaAs structures under varying conditions of deposition of the silicon layer, in contrast to a barrier height of 0.78 eV without the silicon layer. The conduction-band offset between Si and GaAs is estimated to be of the order of 0.3±0.05 eV. The results indicate that the Fermi level at the interface of GaAs on Si in the Al/Si/n-GaAs structure is unpinned from its midgap value.