Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 12: Postersitzung (Struktur und Dynamik reiner Oberfl
ächen, Grenzfl
äche fest-flüssig, Nanostrukturen, Teilchen und Cluster, Halbleiteroberfl
ächen und Grenzfl
ächen, Zeitaufgelöste Spektroskopie, Rastersondentechniken, Methodisches)

O 12.61: Poster

Montag, 24. März 2003, 18:00–21:00, P1

Synchrotron Photoemission Spectroscopy Study of GaAs (100) Surface Etched with Aqueous Ammonia Solution — •Mikhail Lebedev, David Ensling, Ralf Hunger, Thomas Meyer, and Wolfram Jaegermann — TU-Darmstadt, Surface Physics Department, Petersenstr. 23, 64287, Darmstadt

The native-oxide-covered GaAs(100) surface etched with aqueous ammonia solution and annealed in vacuum was studied by means of synchrotron-radiation photoemission spectroscopy. The etching with aqueous ammonia solution resulted in complete removal of arsenic and gallium oxides from the surface and the surface became covered by elemental arsenic as well as by arsenic and gallium hydroxides. The surface oxygen content reduced by a factor of 8 after etching, whereas the surface carbon content was somewhat increased. The surface Fermi level position was 0.95 and 0.5 eV above the valence band maximum for n- and p-type semiconductor, respectively. Annealing of this surface at 450 C resulted in considerable (by a factor of 50) decrease in surface carbon content and decrease in surface oxygen content (by a factor of 2), which was accompanied by disappearance of elemental arsenic and arsenic hydroxide components from As 3d core level spectrum. The surface Fermi level position changed and became 0.8 and 0.3 eV above the valence band maximum for n- and p-type, respectively. The valence band spectra exhibited clear features typical for As-decapped GaAs(100) surfaces.