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Temperature-dependent resistivity of a 10 ML LuAs film and a 600 nm LuAs film normalized by their room-temperature resistivity. Resistivity variation of <20% from 77 K to 297 K is observed in the thin film, and ∼2× in the thick film. The negative temperature coefficient observed is consistent with semimetallic transport.
Transmission spectra for a 0.6 μm film of LuAs and a 0.5 μm film of ErAs. The LuAs film exhibited superior transmission over the technologically important near-IR 1.3–1.55 μm range, despite being 20% thicker. Absorption peaks were red-shifted to longer wavelengths by ∼150 nm in LuAs, as compared with ErAs.
Reflectivity spectra for a 0.6 μm film of LuAs and a 0.5 μm film of ErAs. A red-shift of ∼250 nm is evident in the Drude edge of the LuAs film, with respect to the ErAs film.
Cross-sectional transmission electron microscopy (XTEM) images along (110) zone-axis of a LuAs/GaAs multilayer stack. (a) The complete multilayer structure, (b) planar defect formation following the 3.0 ML deposition of LuAs, (c) 1.0 ML deposition of LuAs nanoparticles.
Plan-view transmission electron microscopy image of a LuAs/GaAs multilayer stack, 1.8 ML LuAs/50 nm GaAs 5× repetition. Imaged sample 20–70 nm in thickness, potentially showing 1–2 nanoparticle layers.
Absorption spectra for LuAs superlattice structures (and similarly grown ErAs superlattice structures), each 1 μm total epi-layer thickness, with equal volumetric RE-As concentration. The absorption peak shifted to longer wavelengths for larger depositions, while maintaining a relatively narrow linewidth at longer wavelengths.
Sample structures for LuAs and ErAs superlattice absorption studies.
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