ORIENTATION INDEPENDENCE OF HETEROJUNCTION-BAND OFFSETS AT GAAS-ALAS HETEROINTERFACES CHARACTERIZED BY X-RAY PHOTOEMISSION SPECTROSCOPY

We systematically studied the orientation and the growth sequence dependence of the valence-band offset ΔEv at the lattice-matched common anion GaAs-AlAs interfaces. High quality GaAs-AlAs heterojunctions were carefully grown on GaAs substrates with three major orientations, namely, (100), (110), and (111)B. The core level energy distance ΔECL between Ga 3d and Al 2p levels was measured by in situ x-ray photoemission spectroscopy. ΔECL is found to be independent of the substrate orientation and the growth sequence, which clearly indicates the face independence of ΔEv. This result suggests that the band lineup at lattice-matched isovalent semiconductor heterojunctions is determined </m1;&6p>by the bulk properties of the constituent materials. ΔEv is determined to be 0.44 ± 0.05 eV.