The atomic structure of (2 x 4) reconstructed Ga0.52In0.48P (001) surfaces was analyzed by using scanning tunnelling microscopy and soft X-ray photo-emission spectroscopy. The epitaxial samples were lattice-matched to GaAs(001) by using metal-organic vapour phase methods. The surfaces were passivated by a P/As double-layer cap immediately after growth, and were then transferred to an ultra-high vacuum for surface characterization. Uncontaminated well-ordered (2 x 4) reconstructions were reproducibly formed under ultra-high vacuum conditions by annealing (460C, 600s). Atomic resolution scanning tunnelling microscopic images were obtained which exhibited features that were typical of the mixed-dimer (2 x 4) structure; as seen on InP(001). This interpretation was supported by the appearance of 2 surface core-level components in the soft X-ray photo-emission spectroscopy spectra of In 4d and Ga 3d, plus one in the P 2p emission line; as expected for the mixed-dimer structure. Further annealing of the sample at higher temperatures degraded the surface without producing any further reconstruction. The (2 x 4) mixed-dimer structure thus represented the most III-rich (least P-rich) stable (001) surface.

Surface Structure of Ordered InGaP(001): the (2x4) Reconstruction. P.Vogt, K.Lüdge, M.Zorn, M.Pristovsek, W.Braun, W.Richter, N.Esser: Physical Review B, 2000, 62[19], 12601-4