Smooth, monocrystalline (100) surfaces of the alloys In1−xGaxAs and GaSb1−y Asy were prepared by molecular beam epitaxy. Both As-stabilized c(2 × 8) and metal-stabilized c(8 × 2) surface reconstructions were observed for In1−xGaxAs over the entire alloy range. GaSb1−yAsy exhibited a c(2 × 6) or (2 × 3) structure for y ≲ 0.2, and, after a transition region, the anion-stabilized c(2 × 8) or the Ga-stabilized c(8 × 2) structures for y ≳ 0.5. Electron energy loss spectroscopy revealed the simultaneous presence of two empty, dangling-bond derived surface states in both alloy systems. For In1−xGaxAs the In-derived empty surface state lies ≈0.4–0.5 eV below that of Ga and moves from above the conduction band edge into the band gap for x ≳ 0.6. The overlap between the Ga-and In-derived empty surface states causes the quenching of the Ga(3d) surface exciton. For GaSb1−yAsy the Sb dangling bonds generate an empty, localized surface state which lies 0.2–0.3 eV above the empty, Ga-derived surface state. Both levels lie above the conduction band edge throughout the alloy range.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.