skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

Abstract

Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure siliconmore » case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics.« less

Authors:
 [1]; ; ;  [2];  [3]
  1. Department of Physics, State University of New York at Albany, Albany, New York 12222 (United States)
  2. College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, New York 12203 (United States)
  3. Department of Physics, University of North Dakota, Grand Forks, North Dakota 58203 (United States)
Publication Date:
OSTI Identifier:
22399330
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; EXCITATION; HYDROGEN IONS; LAYERS; MONOCRYSTALS; NANOPARTICLES; NANOSTRUCTURES; OPTOELECTRONIC DEVICES; PHOTOVOLTAIC EFFECT; PLASMONS; RED SHIFT; REFRACTIVE INDEX; RESONANCE; SILICON; SILVER; SURFACES; THIN FILMS; VISIBLE RADIATION

Citation Formats

Akhter, Perveen, Huang, Mengbing, E-mail: mhuang@albany.edu, Spratt, William, Kadakia, Nirag, and Amir, Faisal. Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications. United States: N. p., 2015. Web. doi:10.1063/1.4916253.
Akhter, Perveen, Huang, Mengbing, E-mail: mhuang@albany.edu, Spratt, William, Kadakia, Nirag, & Amir, Faisal. Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications. United States. doi:10.1063/1.4916253.
Akhter, Perveen, Huang, Mengbing, E-mail: mhuang@albany.edu, Spratt, William, Kadakia, Nirag, and Amir, Faisal. Sat . "Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications". United States. doi:10.1063/1.4916253.
@article{osti_22399330,
title = {Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications},
author = {Akhter, Perveen and Huang, Mengbing, E-mail: mhuang@albany.edu and Spratt, William and Kadakia, Nirag and Amir, Faisal},
abstractNote = {Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics.},
doi = {10.1063/1.4916253},
journal = {Journal of Applied Physics},
number = 12,
volume = 117,
place = {United States},
year = {Sat Mar 28 00:00:00 EDT 2015},
month = {Sat Mar 28 00:00:00 EDT 2015}
}
  • Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal structures of silicon carbide (SiC) are presented from 1200-35000 cm{sup -1} ({lambda} {approx} 8-0.28 {mu}m) and used to improve the accuracy of optical functions (n and k) from the infrared (IR) to the ultraviolet (UV). Comparison with previous {lambda} {approx} 6-20 {mu}m thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for k in the IR region. We extract n and k needed for radiative transfer models using a new 'difference method', which utilizes transmission spectra measured frommore » two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral regions, 3C ({beta}-SiC) and the E-vector perpendicular c-vector polarization of 6H (a type of {alpha}-SiC) have almost identical optical functions that can be substituted for each other in modeling astronomical environments. Optical functions for E-vector || c-vector of 6H SiC have peaks shifted to lower frequency, permitting identification of this structure below {lambda} {approx} 4 {mu}m. The onset of strong UV absorption for pure SiC occurs near 0.2 {mu}m, but the presence of impurities redshifts the rise to 0.33 {mu}m. Optical functions are similarly impacted. Such large differences in spectral characteristics due to structural and chemical effects should be observable and provide a means to distinguish chemical variation of SiC dust in space.« less
  • In this article, we explore the possibility of modifying the silicon nanocrystal areal density in SiO{sub x} single layers, while keeping constant their size. For this purpose, a set of SiO{sub x} monolayers with controlled thickness between two thick SiO{sub 2} layers has been fabricated, for four different compositions (x = 1, 1.25, 1.5, or 1.75). The structural properties of the SiO{sub x} single layers have been analyzed by transmission electron microscopy (TEM) in planar view geometry. Energy-filtered TEM images revealed an almost constant Si-cluster size and a slight increase in the cluster areal density as the silicon content increases in themore » layers, while high resolution TEM images show that the size of the Si crystalline precipitates largely decreases as the SiO{sub x} stoichiometry approaches that of SiO{sub 2}. The crystalline fraction was evaluated by combining the results from both techniques, finding a crystallinity reduction from 75% to 40%, for x = 1 and 1.75, respectively. Complementary photoluminescence measurements corroborate the precipitation of Si-nanocrystals with excellent emission properties for layers with the largest amount of excess silicon. The integrated emission from the nanoaggregates perfectly scales with their crystalline state, with no detectable emission for crystalline fractions below 40%. The combination of the structural and luminescence observations suggests that small Si precipitates are submitted to a higher compressive local stress applied by the SiO{sub 2} matrix that could inhibit the phase separation and, in turn, promotes the creation of nonradiative paths.« less
  • We demonstrate that the broad surface plasmon resonance (SPR) of a single layer of near-coalescence silver nanoparticles (NPs), embedded in a dielectric matrix can be tailored by irradiation with a single nanosecond laser pulse into a distribution featuring a sharp resonance at 435 nm. Scanning electron microscopy studies reveal the underlying mechanism to be a transformation into a distribution of well-separated spherical particles. Additional exposure to multiple femtosecond laser pulses at 400 nm or 800 nm wavelength induces polarization anisotropy of the SPR, with a peak shift that increases with laser wavelength. The spectral changes are measured in-situ, employing reflection and transmission micro-spectroscopymore » with a lateral resolution of 4 μm. Spectral maps as a continuous function of local fluence can be readily produced from a single spot. The results open exciting perspectives for dynamically tuning and switching the optical response of NP systems, paving the way for next-generation applications.« less
  • The development of small sized laser operating above room temperature is important in the realization of optical integrated circuits. Recently, micro-lasers consisting of photonic crystals (PhCs) and whispering gallery mode cavities have been demonstrated. Optically pumped laser devices could be easily designed using photonic crystal-slab waveguides (PhC-WGs) with an air-bridge type structure. In this study, we observe lasing at 1.3μm from two-photon pumped InAs-quantum-dots embedded GaAs PhC-WGs above room temperature. This type of compact laser shows promise as a new light source in ultra-compact photonics integrated circuits.