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O: Fachverband Oberflächenphysik
O 11: Plasmonics and Nanooptics II: Light-Matter Interaction
O 11.2: Vortrag
Montag, 20. März 2017, 15:15–15:30, TRE Ma
AlN/GaN multilayer interface phonons studied with mid-IR second-harmonic phonon spectroscopy — •Christopher J. Winta1, Nikolai Paßler1, Ilya Razdolski1, D. Scott Katzer2, Ioannis Chatzakis3, Neeraj Nepal2, David J. Meyer2, Chase T. Ellis2, Joseph G. Tischler2, Alexander J. Giles2, Sandy Gewinner1, Wieland Schöllkopf1, Martin Wolf1, Joshua D. Caldwell2, and Alexander Paarmann1 — 1Fritz-Haber-Institut der MPG, Faradayweg 4–6, 14195 Berlin — 2U.S. Naval Research Laboratory, Washington, D.C. 20375 — 3NRC Postdoctoral Fellow (residing at NRL, Washington D.C. 20375)
Combining multiple atomic-scale layers of polar crystals allows for active modification of phonon lifetimes, frequencies and hence engineering of Reststrahlen band spectral positions. Specifically, new interface optical phonon modes emerge in these so-called crystalline hybrids (XHs). The atomic-scale layer thicknesses allow for tuning of these modes, opening up a new class of engineered materials [1].
In our experiments, we study the nonlinear response of an AlN/GaN 27-layer superlattice material on a SiC substrate with varying layer thicknesses ranging from ∼2 to 4 nm independently for both constituents by means of mid-IR second-harmonic phonon spectroscopy [2]. The higher spectral resolution of SHG as compared to reflectivity allows us to uniquely assign peaks to specific modes. In consequence, we are able to identify interface phonons by their layer thickness dependent behavior. [1] Caldwell et al., Nat. Nanotechnol. 11, 9–15 (2016); [2] Paarmann et al., Phys. Rev. B 94, 134312 (2016)