Enhancement of Radiative Recombination in Silicon via Phonon Localization and Selection‐Rule Breaking

Cloutier, Sylvain G.; Hsu, Chih-Hsun; Kossyrev, Pavel A.; Xu, Jimmy

doi:10.1002/adma.200600001

Cited by 46 publications

(34 citation statements)

References 22 publications

(38 reference statements)

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“…Si nanowires fabricated by MACE generally possess high crystalline quality, although the surface roughness of these nanowires is higher compared to VLS-grown nanowires. Compared to dry etching (e.g., RIE), chemical-based etching is considered a gentler process which tends to introduce fewer surface defects in the remaining material [16]. Recently, Oh et al reported an 18.2% cell efficiency for a MACE textured front junction device [17].…”

Section: Introductionmentioning

confidence: 99%

Passivation of all-angle black surfaces for silicon solar cells

Rahman

Bonilla

Nawabjan

et al. 2017

Solar Energy Materials and Solar Cells

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Abstract-Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles supports the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30 cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells.

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Section: Introductionmentioning

confidence: 99%

Passivation of all-angle black surfaces for silicon solar cells

Rahman

Bonilla

Nawabjan

et al. 2017

Solar Energy Materials and Solar Cells

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“…TEM images showing evidence of compressive strain in the pore walls are presented in ref. 28. The linewidth broadening in the C-enriched nanopatterned SOI versus the reference nanopatterned SOI is likely due to the presence of a variety of strain environments caused by C i s, C s s and other residual damage present after amorphization, C implantation, and SPE regrowth.…”

Section: Discussion : G Center Luminescence Model In Nanopatterned Simentioning

confidence: 99%

Stimulated emission and emission efficiency enhancement in nanopatterned silicon

Rotem

Shainline

2007

SPIE Proceedings

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ABSTRACT1.278µm laser emission has been observed in a SOI structure which has been nanopatterned to contain an array of nanopores. The optical transition is identified to be associated with phononless recombination mediated by the bistable, carbon-related G center. The present work is focused on increasing the luminescence intensity from nanopatterned Si by increasing the number of G centers present in the material. The G center density is increased by increasing the concentration of substitutional atoms in the lattice prior to nanopatterning. To this end, solid-phase epitaxial regrowth of carbon-rich silicon is utilized in order to take advantage of the increased solid solubility of carbon in silicon at the interface between crystalline and amorphous solid silicon.

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“…phonon lasers [34]. Other applications may include optical cooling [35], THz energy conversion via acoustoluminescence mechanism [36] and increasing efficiency of light emission in silicon [37]. Hypersonic phononic crystals could also have a large impact in thermal management.…”

Section: Symmetry and Phononic Band Gapsmentioning

confidence: 99%

Hypersonic phononic crystals

Gorishnyy¹,

Ullal²,

Maldovan³

et al. 2006

The Journal of the Acoustical Society of America

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Manipulation of the distribution of phonons ini a solid is important for both basic science and applications ranging from heat management to reduction of noise in electronic circuits and creating materials with superior acoustic and acousto-optical properties. This thesis explores hypersonic phononic crystals as means to achieve control over high frequency acoustic phonons. An integrated approach to fabrication, measurement and analysis of hypersonic phononic crystals with band gaps in the GHz range is presented.First, the phonon dispersion relation for one dimensional polymeric phononic crystals fabricated by coextrusion of a large number of poly(methylmethacrylate)/poly(carbonate) and poly(methylmethacrylate)/poly(ethylene terephthalate) bilayer pairs is investigated as a function of a lattice constant and composition using Brillouin light scattering and numerical simulations. This set of relatively simple multilayer structures represents an excellent platform to gain a basic understanding of phononic band gap phenomena. In addition, their in-plane phonon dispersion is used to extract information about the elastic constants and glass transition temperatures of individual nanolayers in a periodic multilayer arrangement. Next, two dimensional epoxy/air phononic crystals fabricated in a photoresist using interference lithography are studied. These structures are 2D single crystalline, enabling direction-resolved measurements of their phonon dispersion relation. with performance characteristics that can be adjusted dynamically during operation. The investigations described in this thesis demonstrate both theoretically and experimentally that 1D, 2D and 3D periodic submicron structures have complex phonon dispersion relations at GHz frequencies. As a result, these crystals can be used to manipulate the flow of random thermal phonons as well as externally generated acoustic waves resulting in novel acoustic and thermal properties.

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Enhancement of Radiative Recombination in Silicon via Phonon Localization and Selection‐Rule Breaking

Cited by 46 publications

References 22 publications

Passivation of all-angle black surfaces for silicon solar cells

Passivation of all-angle black surfaces for silicon solar cells

Stimulated emission and emission efficiency enhancement in nanopatterned silicon

Hypersonic phononic crystals

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