RESUMEN
The wet-chemical synthesis of 3D confined antimony nanoparticles (Sb-NP) at low and high temperatures is described. Using reaction conditions that are mild in temperature and strong in reducing power allows the synthesis of amorphous Sb-NP stabilized with organic ligands. Exchanging the organic ligand 1-octanethiol by iodide enabled to investigate the unusual strong stability of this metastable material through simultaneous thermal analysis combining differential scanning calorimetry and thermogravimetric analysis. Additionally, in situ high temperature powder x-ray diffraction (p-XRD) shows a significant increase in stabilization of the amorphous phase in comparison to thin layered, 1D confined Sb or bulk material. Further, it is shown with scattering-type scanning near-field optical microscopy (s-SNOM) experiments that the optical response of the different phases in Sb-NP make the distinctness of each phase possible. It is proposed that the Sb-NP introduced here can serve as a 3D-confined optically addressable nanomaterial of miniaturized phase change memory devices.
RESUMEN
Tailoring light-matter interaction is essential to realize nanophotonic components. It can be achieved with surface phonon polaritons (SPhPs), an excitation of photons coupled with phonons of polar crystals, which also occur in 2d materials such as hexagonal boron nitride or anisotropic crystals. Ultra-confined resonances are observed by restricting the SPhPs to cavities. Phase-change materials (PCMs) enable non-volatile programming of these cavities based on a change in the refractive index. Recently, the plasmonic PCM In3SbTe2 (IST) was introduced which can be reversibly switched from an amorphous dielectric state to a crystalline metallic one in the entire infrared to realize numerous nanoantenna geometries. However, reconfiguring SPhP resonators to modify the confined polaritons modes remains elusive. Here, we demonstrate direct programming of confined SPhP resonators by phase-switching IST on top of a polar silicon carbide crystal and investigate the strongly confined resonance modes with scanning near-field optical microscopy. Reconfiguring the size of the resonators themselves result in enhanced mode confinements up to a value of λ / 35 . Finally, unconventional cavity shapes with complex field patterns are explored as well. This study is a first step towards rapid prototyping of reconfigurable SPhP resonators that can be easily transferred to hyperbolic and anisotropic 2d materials.
RESUMEN
Extended defects in wide-bandgap semiconductors have been widely investigated using techniques providing either spectroscopic or microscopic information. Nano-Fourier transform infrared spectroscopy (nano-FTIR) is a nondestructive characterization method combining FTIR with nanoscale spatial resolution (â¼20 nm) and topographic information. Here, we demonstrate the capability of nano-FTIR for the characterization of extended defects in semiconductors by investigating an in-grown stacking fault (IGSF) present in a 4H-SiC epitaxial layer. We observe a local spectral shift of the mid-infrared near-field response, consistent with the identification of the defect stacking order as 3C-SiC (cubic) from comparative simulations based on the finite dipole model (FDM). This 3C-SiC IGSF contrasts with the more typical 8H-SiC IGSFs reported previously and is exemplary in showing that nanoscale spectroscopy with nano-FTIR can provide new insights into the properties of extended defects, the understanding of which is crucial for mitigating deleterious effects of such defects in alternative semiconductor materials and devices.