M. Mallmann, R. Niklaus, T. Rackl, M. Benz, T. G. Chau, D. Johrendt, J. Minár, W. Schnick Solid Solutions of Grimm–Sommerfeld Analogous Nitride Semiconductors II‐IV‐N2 (II=Mg, Mn, Zn; IV=Si, Ge): Ammonothermal Synthesis and DFT Calculations Journal Article Chem. Eur. J., 25 , pp. 1-10, 2019, ISSN: 1521-3765. Abstract | Links @article{Mallmann2019,
title = {Solid Solutions of Grimm\textendashSommerfeld Analogous Nitride Semiconductors II‐IV‐N2 (II=Mg, Mn, Zn; IV=Si, Ge): Ammonothermal Synthesis and DFT Calculations },
author = {M. Mallmann and R. Niklaus and T. Rackl and M. Benz and T. G. Chau and D. Johrendt and J. Min\'{a}r and W. Schnick},
doi = {https://doi.org/10.1002/chem.201903897},
issn = {1521-3765},
year = {2019},
date = {2019-09-17},
journal = {Chem. Eur. J.},
volume = {25},
pages = {1-10},
abstract = {Grimm\textendashSommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa1−xIIbx)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Grimm–Sommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa1−xIIbx)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach. |
K Hübner, M Pilo-Pais, F Selbach, T Liedl, P Tinnefeld, F D Stefani, G P Acuna Directing Single-Molecule Emission with DNA Origami-Assembled Optical Antennas Journal Article Nano Letters, 19 (9), pp. 6629-6634, 2019, ISSN: 1530-6984. Abstract | Links @article{,
title = {Directing Single-Molecule Emission with DNA Origami-Assembled Optical Antennas},
author = {K H\"{u}bner and M Pilo-Pais and F Selbach and T Liedl and P Tinnefeld and F D Stefani and G P Acuna},
url = {https://doi.org/10.1021/acs.nanolett.9b02886},
doi = {10.1021/acs.nanolett.9b02886},
issn = {1530-6984},
year = {2019},
date = {2019-09-11},
journal = {Nano Letters},
volume = {19},
number = {9},
pages = {6629-6634},
abstract = {Abstract Conventional surface enhanced Raman scattering (SERS) substrates are well known for their supreme electromagnetic enhancements and ultrahigh sensitivity in detecting molecules at low concentrations. However, large-area quasi-uniform SERS substrates are difficult to achieve by standard top-down nanofabrication techniques, resulting in fluctuant SERS responses and unwanted fluorescence interferences, which severely limit their performances in practical applications. To tackle these challenges, a large-scale quasi-uniform hybrid graphene fragmented-gold substrate with stable and reproducible SERS readouts as well as large enhancement factors over an ultrawideband spectrum is developed. The hybrid substrate is fabricated via cold-etching through a controllable break up of a thin gold film followed by a graphene transfer. The stimulated localized surface plasmons interact strongly with the graphene layer, leading to spectrally and spatially modified graphene-mediated surface enhanced Raman scattering (GSERS) responses. The perfect monolayer graphene of the GSERS substrate prevents adsorbates from the atmosphere and direct contact between bonded molecules and gold, thus reducing the catalytic activity of gold and producing clean, stable, and reproducible molecular Raman signals. The easy-fabricated hybrid GSERS substrate not only provides a powerful platform to collect robust molecular Raman spectra but also shows great potentials for future mass production of high-performance nanophotonic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Conventional surface enhanced Raman scattering (SERS) substrates are well known for their supreme electromagnetic enhancements and ultrahigh sensitivity in detecting molecules at low concentrations. However, large-area quasi-uniform SERS substrates are difficult to achieve by standard top-down nanofabrication techniques, resulting in fluctuant SERS responses and unwanted fluorescence interferences, which severely limit their performances in practical applications. To tackle these challenges, a large-scale quasi-uniform hybrid graphene fragmented-gold substrate with stable and reproducible SERS readouts as well as large enhancement factors over an ultrawideband spectrum is developed. The hybrid substrate is fabricated via cold-etching through a controllable break up of a thin gold film followed by a graphene transfer. The stimulated localized surface plasmons interact strongly with the graphene layer, leading to spectrally and spatially modified graphene-mediated surface enhanced Raman scattering (GSERS) responses. The perfect monolayer graphene of the GSERS substrate prevents adsorbates from the atmosphere and direct contact between bonded molecules and gold, thus reducing the catalytic activity of gold and producing clean, stable, and reproducible molecular Raman signals. The easy-fabricated hybrid GSERS substrate not only provides a powerful platform to collect robust molecular Raman spectra but also shows great potentials for future mass production of high-performance nanophotonic devices. |
G Grinblat, I Abdelwahab, M P Nielsen, P Dichtl, K Leng, R F Oulton, K P Loh, S A Maier Ultrafast All-Optical Modulation in 2D Hybrid Perovskites Journal Article ACS Nano, 13 (8), pp. 9504-9510, 2019, ISSN: 1936-0851. Links @article{,
title = {Ultrafast All-Optical Modulation in 2D Hybrid Perovskites},
author = {G Grinblat and I Abdelwahab and M P Nielsen and P Dichtl and K Leng and R F Oulton and K P Loh and S A Maier},
url = {https://doi.org/10.1021/acsnano.9b04483},
doi = {10.1021/acsnano.9b04483},
issn = {1936-0851},
year = {2019},
date = {2019-08-27},
journal = {ACS Nano},
volume = {13},
number = {8},
pages = {9504-9510},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
