Dresden 2006 – scientific programme
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DS: Dünne Schichten
DS 13: Internal Symposium “Nanoengineered thin films”
DS 13.5: Invited Talk
Wednesday, March 29, 2006, 17:15–18:00, GER 37
Self-assembled Al0.53In0.47N nano-grass with intrinsically curved crystal structure — •Jens Birch1, Timo Seppänen1, György Z. Radnoczi2, Bela Pécz2, and Lars Hultman1 — 1IFM, Linköping University, SE-58216 Linköping, Sweden — 2Res. Inst. for Tech. Phys. and Mat. Sci. of the Hungarian Academy of Sciences, H-1525 Budapest, P. O. Box 59, Hungary
Al1−xInxN is a very attractive semiconductor as the direct band-gap, ranging from 0.9 eV for InN to 6.2 eV for AlN, opens possibilities to engineer opto-electronic devices operating from near infra-red to deep ultra-violet. However, a miscibility gap in Al1−xInxN between 0.1 < x < 0.9 implies a necessity of low-temperature growth under kinetically limited adatom conditions. In this work epilayers of semiconducting Al1−xInxN were grown by reactive magnetron sputter epitaxy (MSE) with directional fluxes of Al and In onto static (111)-oriented single crystal ZrN seed layers under ultra-high-vacuum conditions at a temperature of 300 ∘C. High resolution electron microscopy of Al0.53In0.47N reveals densely packed ≈10 nm wide single crystal whiskers growing with curvature of approximately 0.09∘/nm, giving about 26.5∘ for the entire length (300 nm) of the column, as confirmed by X-ray diffraction. It is shown that a generically new materials structure is formed which is characterized by extreme crystal lattice curvature caused by a lateral 2-dimensional lattice parameter gradient due to a gradual intra-domain lateral compositional variation. We present a model for this unique, self-assembled, nanograss-like curved crystal structure and its implications are discussed.