Nanowire Heating by Optical Electromagnetic Irradiation

Roder, Paden B.; Pauzauskie, Peter J.; Davis, E. James

doi:10.1021/la303250e

Cited by 29 publications

(36 citation statements)

References 60 publications

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“…Recently, a 2-D silicon PC was shown to increase absorption efficiency of photovoltaic cells by 31% when compared with a c-Si film with a distributed Bragg reflector [20]. Additionally, analytical theory has shown that morphology-dependent res- onances can enhance internal fields in silicon nanowires [21]. Experimental results have demonstrated increased absorption in nanowire-patterned silicon as compared with planar silicon across the visible and near-infrared regions of the electromagnetic spectrum [22].…”

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confidence: 99%

Recovery of hexagonal Si-IV nanowires from extreme GPa pressure

Smith

Zhou

Roder

et al. 2016

Journal of Applied Physics

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We use Raman spectroscopy in tandem with transmission electron microscopy and DFT simulations to show that extreme (GPa) pressure converts the phase of silicon nanowires from cubic (Si-I) to hexagonal (Si-IV) while preserving the nanowire's cylindrical morphology. In situ Raman scattering of the TO mode demonstrates the high-pressure Si-I to Si-II phase transition near 9 GPa. Raman signal of the TO phonon shows a decrease in intensity in the range 9 to 14 GPa. Then, at 17 GPa, it is no longer detectable, indicating a second phase change (Si-II to Si-V) in the 14 to 17 GPa range. Recovery of exotic phases in individual silicon nanowires from diamond anvil cell experiments reaching 17 GPa is also shown. Raman measurements indicate Si-IV as the dominant phase in pressurized nanowires after decompression. Transmission electron microscopy and electron diffraction confirm crystalline Si-IV domains in individual nanowires. Computational electromagnetic simulations suggest that heating from the Raman laser probe is negligible and that near-hydrostatic pressure is the primary driving force for the formation of hexagonal silicon nanowires.Silicon is the second most abundant element in the Earth's crust [1] and the foundation of the modern electronics industry. It is used for integrated circuits in information technology and as an energy conversion material in photovoltaics. Unfortunately, one of the biggest drawbacks for silicon's use in solar energy conversion is its indirect band gap. Theoretical [2,3] and experimental [4][5][6] efforts are looking at the properties of exotic phases of silicon and their potential as improved photovoltaic (PV) absorbers.The phase diagram of silicon [7] reveals several polytypes at elevated pressures. At a pressure of ∼11 GPa, Si-I begins to transition to Si-II which has a body-centered tetragonal crystal structure and metallic electronic structure [8]. As pressure increases past approximately 15 GPa, Si-V begins to emerge with a primitive hexagonal phase [9][10][11]. But neither Si-II nor Si-V are stable at atmospheric pressure and, therefore, have not been observed experimentally outside of high pressures. Si-III (body-centered cubic) and Si-IV (diamond hexagonal), however, are stable at atmospheric pressure and have been synthetisized [4,12,13] as well as recovered from high-pressure phase transitions [14,15]. While Si-III is a semimetal [14] and could have applications in electronics, Si-IV is a semiconductor with a reported indirect band gap near 0.8-0.9 eV and direct transition at 1.5 eV [13]. The direct transition for Si-IV makes * peterpz@uw.edu FIG. 1. Schematic of the diamond anvil cell (DAC) and components for Raman scattering measurements. A holographic laser bandpass (HLB) filter is used to pass the 532 nm Raman probe into a 50x objective which focused the beam into DAC. Nanowire Raman scattering and ruby photoluminescence were collected with the same objective and sent to a spectrometer or CCD for imaging. A 532 nm notch filter (NF) was used to eliminate strong Rayleigh scat...

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Recovery of hexagonal Si-IV nanowires from extreme GPa pressure

Smith

Zhou

Roder

et al. 2016

Journal of Applied Physics

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“… The normalized electric field distribution,

(E \cdot E^{*}) / E_{0}^{2}

, for an infinitely long 500 nm diameter silicon cylinder in water irradiated with λ 0 =980 nm (a) using the analytical results of Bohren and Huffman and (b) using MEEP. Figure reproduced with permission from reference copyright the American Chemical Society.…”

Section: Photothermal Heating Theorymentioning

confidence: 99%

Photothermal Heating and Cooling of Nanostructures

Crane

Zhou

Davis

et al. 2018

Chemistry An Asian Journal

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A vast range of insulating, semiconducting, and metallic nanomaterials have been studied over the past several decades with the aim of understanding how continuous-wave or pulsed laser radiation can influence their chemical functionality and local environment. Many fascinating observations have been made during laser irradiation including, but not limited to, the superheating of solvents, mass-transport-mediated morphology evolution, photodynamic therapy, morphology dependent resonances, and a range of phase transformations. In addition to laser heating, recent experiments have demonstrated the laser cooling of nanoscale materials through the emission of upconverted, anti-Stokes photons by trivalent rare-earth ions. This Focus Review outlines the analytical modeling of photothermal heat transport with an emphasis on the experimental validation of anti-Stokes laser cooling. This general methodology can be applied to a wide range of photothermal applications, including nanomedicine, photocatalysis, and the synthesis of new materials. The review concludes with an overview of recent advances and future directions for anti-Stokes cooling.

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“…Generally, the source term Q ( r , t ) is dependent on the complex internal electric fields generated by irradiation as well as the electrical conductivity at optical frequencies and is given by 88 :

Q (boldr, t) = \frac{1}{2} σ \overset{E}{true} (boldr, t) \cdot {bold \tilde{E}}^{*} (boldr, t)

where E ( r , t ) and E *( r , t ) are the generated electric field within the NP and its complex conjugate, respectively 88 . The electrical conductivity at optical frequencies is given by 89 :

σ = \frac{4 π n k}{λ_{i} μ c}

where λ i is the incident wavelength, μ is the nanoparticles relative magnetic permeability, c is the speed of light, and n and k are the real and imaginary parts of the index of refraction of the nanoparticle, respectively 88 .…”

Section: Introductionmentioning

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Nanoscale materials for hyperthermal theranostics

et al. 2015

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Recently, the use of nanoscale materials has attracted considerable attention with the aim of designing personalized therapeutic approaches that can enhance both spatial and temporal control over drug release, permeability, and uptake. Potential benefits to patients include the reduction of overall drug dosages, enabling the parallel delivery of different pharmaceuticals, and the possibility of enabling additional functionalities such as hyperthermia or deep-tissue imaging (LIF, PET, etc.) that complement and extend the efficacy of traditional chemotherapy and surgery. This mini-review is focused on an emerging class of nanometer-scale materials that can be used both to heat malignant tissue to reduce angiogenesis and DNA-repair while simultaneously offering complementary imaging capabilities based on radioemission, optical fluorescence, magnetic resonance, and photoacoustic methods.

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Nanowire Heating by Optical Electromagnetic Irradiation

Cited by 29 publications

References 60 publications

Recovery of hexagonal Si-IV nanowires from extreme GPa pressure

Recovery of hexagonal Si-IV nanowires from extreme GPa pressure

Photothermal Heating and Cooling of Nanostructures

Nanoscale materials for hyperthermal theranostics

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