Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 61: GaN: Preparation and Characterization II (mainly structural)
HL 61.3: Vortrag
Mittwoch, 28. März 2012, 15:30–15:45, EW 202
InGaN(0001) surface reconstructions — •C. Friedrich1, A. Biermann1, N. Esser1,2, M. Kneissl1, and P. Vogt1 — 1TU Berlin, Inst. f. Festkörperphysik EW6-1, Hardenbergstr. 36, 10623 Berlin, Germany — 2Leibniz-Inst. für Analytische Wissenschaften - ISAS e.V., Albert-Einstein Str. 9, 12489 Berlin, Germany
Surfaces of the InGaN alloy system are hardly understood in terms of their atomic structure. In order to reveal the principal mechanisms for the formation of surface reconstructions the preparation of such surfaces for measurements in ultra high vacuum (UHV) is crucial. The preparation and surface structure of high quality group-III-polar (0001) InGaN layers grown by metal-organic vapor phase epitaxy have been investigated. We show that different InGaN surface reconstructions such as (1×1), (1+1/6), (2×2) and (√3×√3)R30∘ can be obtained by annealing at various temperatures under ultra high vacuum and nitrogen-rich conditions as observed by low energy electron diffraction. Depending on the annealing temperature and nitrogen supply these surfaces exhibit significant differences in stoichiometry and morphology as determined by Auger electron spectroscopy and atomic force microscopy measurements. We show that the (2×2) and (√3×√3)R30∘ are explained by indium-adatoms and a related In depletion in the first group-III layer underneath whereas the (1+1/6) exhibits a discommensurate overlayer of group-III-atoms. Strain-relaxation is suggested to explain this structure formation.