scholarly journals Observation of strongly enhanced photoluminescence from inverted cone-shaped silicon nanostructures

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Sebastian W. Schmitt ◽  
George Sarau ◽  
Silke Christiansen
Keyword(s):  
Silicon Nanowires ◽  
Near Infrared ◽  
Numerical Aperture ◽  
Mode Analysis ◽  
Whispering Gallery ◽  
Enhanced Photoluminescence ◽  
Wafer Substrate ◽  
Reverse Taper ◽  
Quality Factor Q ◽  
Nir Luminescence

Abstract Silicon nanowires (SiNWs) attached to a wafer substrate are converted to inversely tapered silicon nanocones (SiNCs). After excitation with visible light, individual SiNCs show a 200-fold enhanced integral band-to-band luminescence as compared to a straight SiNW reference. Furthermore, the reverse taper is responsible for multifold emission peaks in addition to the relatively broad near-infrared (NIR) luminescence spectrum. A thorough numerical mode analysis reveals that unlike a SiNW the inverted SiNC sustains a multitude of leaky whispering gallery modes. The modes are unique to this geometry and they are characterized by a relatively high quality factor (Q ~ 1300) and a low mode volume (0.2 < (λ/neff)3 < 4). In addition they show a vertical out coupling of the optically excited NIR luminescence with a numerical aperture as low as 0.22. Estimated Purcell factors Fp ∝ Q/V m of these modes can explain the enhanced luminescence in individual emission peaks as compared to the SiNW reference. Investigating the relation between the SiNC geometry and the mode formation leads to simple design rules that permit to control the number and wavelength of the hosted modes and therefore the luminescent emission peaks.

Plasmon-assisted interaction of Si with light, for cancer hyperthermia and electromagnetic energy harvest

2020 ◽  
Vol 92 (2) ◽  
pp. 20101
Author(s):  
Behnam Kheyraddini Mousavi ◽  
Morteza Rezaei Talarposhti ◽  
Farshid Karbassian ◽  
Arash Kheyraddini Mousavi
Keyword(s):  
Silicon Nanowires ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Transition ◽  
Electromagnetic Energy ◽  
Energy Harvest ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Absorption Mechanism ◽  
Near Ir

Metal-assisted chemical etching (MACE) is applied for fabrication of silicon nanowires (SiNWs). We have shown the effect of amorphous sheath of SiNWs by treating the nanowires with SF6 and the resulting reduction of absorption bandwidth, i.e. making SiNWs semi-transparent in near-infrared (IR). For the first time, by treating the fabricated SiNWs with copper containing HF∕H2O2∕H2O solution, we have generated crystalline nanowires with broader light absorption spectrum, up to λ = 1 μm. Both the absorption and photo-luminescence (PL) of the SiNWs are observed from visible to IR wavelengths. It is found that the SiNWs have PL at visible and near Infrared wavelengths, which may infer presence of mechanisms such as forbidden gap transitions other can involvement of plasmonic resonances. Non-radiative recombination of excitons is one of the reasons behind absorption of SiNWs. Also, on the dielectric metal interface, the absorption mechanism can be due to plasmonic dissipation or plasmon-assisted generation of excitons in the indirect band-gap material. Comparison between nanowires with and without metallic nanoparticles has revealed the effect of nanoparticles on absorption enhancement. The broader near IR absorption, paves the way for applications like hyperthermia of cancer while the optical transition in near IR also facilitates harvesting electromagnetic energy at a broad spectrum from visible to IR.

An electrically driven whispering gallery polariton microlaser

Nanoscale ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 5448-5459
Author(s):  
Mingming Jiang ◽  
Peng Wan ◽  
Kai Tang ◽  
Maosheng Liu ◽  
Caixia Kan
Keyword(s):  
Infrared Spectrum ◽  
Near Infrared ◽  
Whispering Gallery ◽  
Near Infrared Spectrum

An electrically driven whispering gallery polariton microlaser composed of a ZnO:Ga microwire and a p-GaAs template was fabricated. Its working characteristics of polariton lasing in the near-infrared spectrum were demonstrated.

Multi-Site Cr3+ Occupation Related Broadband NIR Luminescence in Cr3+-doped Li3Mg2NbO6

CrystEngComm ◽  
2021 ◽  
Author(s):  
Fen Xiao ◽  
Chengning Xie ◽  
Shikun Xie ◽  
Rongxi Yi ◽  
Huiling Yuan ◽  
...  
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Luminescent Materials ◽  
Optical Source ◽  
Nir Emission ◽  
Nir Luminescence

Broadband near infrared (NIR) luminescent materials have attracted great attention recently for the advance smart optical source of NIR spectroscopy. In this work, a broadband NIR emission from 650 nm...

Graphene Nanoparticles Decorated Silicon Nanowires with Tungsten Oxide Counter Electrode for Quasi-Solid State Hybrid Solar Cells

2021 ◽  
Author(s):  
Ankita Kolay ◽  
Manoranjan Ojha ◽  
Melepurath Deepa
Keyword(s):  
Ionic Liquid ◽  
Solar Cells ◽  
Solid State ◽  
Tungsten Oxide ◽  
Silicon Nanowires ◽  
Counter Electrode ◽  
Near Infrared ◽  
Hybrid Solar Cells ◽  
Functionalized Graphene ◽  
Graphene Nanoparticles

Anchoring ionic liquid functionalized graphene nanoparticles (IL-GNP) to silicon nanowires (SiNW) improves the solar spectral utilization from visible to near infrared (NIR). Due to the bandgap of IL-GNP in the...

scholarly journals Highly Efficient Silicon Nanowire Surface Passivation by Bismuth Nano-Coating for Multifunctional Bi@SiNWs Heterostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1434
Author(s):  
Mariem Naffeti ◽  
Pablo Aitor Postigo ◽  
Radhouane Chtourou ◽  
Mohamed Ali Zaïbi
Keyword(s):  
Silicon Nanowires ◽  
Near Infrared ◽  
Surface Passivation ◽  
Silicon Nanowire ◽  
Etching Technique ◽  
Highly Efficient ◽  
Broadband Emission ◽  
New Family ◽  
Nano Coating ◽  
Nanowire Surface

A key requirement for the development of highly efficient silicon nanowires (SiNWs) for use in various kinds of cutting-edge applications is the outstanding passivation of their surfaces. In this vein, we report on a superior passivation of a SiNWs surface by bismuth nano-coating (BiNC) for the first time. A metal-assisted chemical etching technique was used to produce the SiNW arrays, while the BiNCs were anchored on the NWs through thermal evaporation. The systematic studies by Scanning Electron Microscopy (SEM), energy dispersive X-ray spectra (EDX), and Fourier Transform Infra-Red (FTIR) spectroscopies highlight the successful decoration of SiNWs by BiNC. The photoluminescence (PL) emission properties of the samples were studied in the visible and near-infrared (NIR) spectral range. Interestingly, nine-fold visible PL enhancement and NIR broadband emission were recorded for the Bi-modified SiNWs. To our best knowledge, this is the first observation of NIR luminescence from Bi-coated SiNWs (Bi@SiNWs), and thus sheds light on a new family of Bi-doped materials operating in the NIR and covering the important telecommunication wavelengths. Excellent anti-reflectance abilities of ~10% and 8% are observed for pure SiNWs and Bi@SiNWs, respectively, as compared to the Si wafer (50–90%). A large decrease in the recombination activities is also obtained from Bi@SiNWs heterostructures. The reasons behind the superior improvement of the Bi@SiNWs performance are discussed in detail. The findings demonstrate the effectiveness of Bi as a novel surface passivation coating, where Bi@SiNWs heterostructures are very promising and multifunctional for photovoltaics, optoelectronics, and telecommunications.

Single crystal polarized spectra in the near-infrared region: a local-mode analysis of the spectra of CsMnCl3•2X2O (X = H, D)

1994 ◽  
Vol 72 (5) ◽  
pp. 1211-1217 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Near Infrared ◽  
Infrared Region ◽  
Chloride Ions ◽  
Mode Analysis ◽  
Local Mode ◽  
Local Modes ◽  
Near Infrared Spectra ◽  
Parameter Values ◽  
Local Mode Analysis

Polarized near-infrared spectra of single crystals of CsMnCl3•2X2O (X = H, D) were recorded at 10 K. Those bands which could be assigned to O—H or O—D stretch overtones were analyzed using local-mode theory specifically adapted for systems having less than C2v symmetry. Both O—H oscillators form nearly linear hydrogen bonds to neighboring chloride ions at different distances. As a result, the local-mode harmonic frequency and anharmonicity parameters show characteristic shifts from their gas-phase values. The parameter values cover an unusually narrow range in this crystal, considering the spread in hydrogen-bond distances. Assignment of stretch overtone bands to specific oscillators in the crystal was made by using the polarization behavior expected of local modes in the oriented gas model. Several of the overtone bands show combinations with lattice modes or low-energy hydrogen-bond modes in unusual detail.

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