Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: Group-III-Nitrides: Optical Properties I

HL 12.2: Vortrag

Montag, 22. März 2010, 14:15–14:30, H15

Spinodal and binodal decomposition of a thin InGaN layer grown on GaN — •Christian Tessarek, Timo Aschenbrenner, Stephan Figge, and Detlef Hommel — Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen

Unstrained InGaN is known to have a large miscibility gap due to spinodal decomposition [1]. Considering strain of an InGaN layer grown on GaN, the spinodal and binodal phase diagram changes significantly [2]: the ciritcal temperature, i.e. the maximum of the spinodal and binodal graph, is reduced and moved to higher x of In_xGa_1−xN.

Strong phase separation of a thin uncapped InGaN layer grown on GaN occurs into both high and low In content phases when the growth parameters are set into the unstable region of this strain considering spinodal phase diagram. The different InGaN phases were determined by x-ray diffraction and photoluminescence measurements. Furthermore, surface analysis of the decomposed structures were performed via scanning electron and atomic force microscopy. The phase separation forms among others dot-like and/or meandering InGaN structures as predicted in [3]. These structures are used as active material in light emitting devices.

[1] Ho, Stringfellow, APL 69, 2701 (1996)

[2] Karpov, MRS Internet J. Nitride Semicon. Res. 3, 16-1 (1998)

[3] Okumura, Ishida, Kamikawa, Jpn. J. Appl. Phys. 39, 1044 (2000)