The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
John V. Badding - One of the best experts on this subject based on the ideXlab platform.
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high pressure chemical vapor deposition of hydrogenated Amorphous Silicon films and solar cells
Advanced Materials, 2016Co-Authors: Todd D Day, Justin R Sparks, Nichole Sullivan, John V. BaddingAbstract:Thin films of hydrogenated Amorphous Silicon can be produced at MPa pressures from silane without the use of plasma at temperatures as low as 345 °C. High pressure chemical vapor deposition may open a new way to low cost deposition of Amorphous Silicon solar cells and other thin film structures over very large areas in very compact, simple reactors.
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nonlinear transmission properties of hydrogenated Amorphous Silicon core optical fibers
Optics Express, 2010Co-Authors: Priyanth Mehta, Neil F Baril, Noel Healy, Pier J. A. Sazio, John V. Badding, Anna C. PeacockAbstract:The nonlinear properties of a low loss hydrogenated Amorphous Silicon core fiber have been characterized for transmission of high power pulses at 1540nm. Numerical modelling of the pulse propagation in the Amorphous core material was used to establish the two-photon absorption, free-carrier absorption and the nonlinear refractive index, which were found to be larger than the values typical for crystalline Silicon. Calculation of a nonlinear figure of merit demonstrates the potential for these hydrogenated Amorphous Silicon core fibers to be used in nonlinear Silicon photonics applications.
D A Papaconstantopoulos - One of the best experts on this subject based on the ideXlab platform.
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high thermal conductivity of a hydrogenated Amorphous Silicon film
Physical Review Letters, 2009Co-Authors: J L Feldman, David G Cahill, Richard S Crandall, Noam Bernstein, D M Photiadis, M J Mehl, D A PapaconstantopoulosAbstract:: We measured the thermal conductivity kappa of an 80 microm thick hydrogenated Amorphous Silicon film prepared by hot-wire chemical-vapor deposition with the 3omega (80-300 K) and the time-domain thermo-reflectance (300 K) methods. The kappa is higher than any of the previous temperature dependent measurements and shows a strong phonon mean free path dependence. We also applied a Kubo based theory using a tight-binding method on three 1000 atom continuous random network models. The theory gives higher kappa for more ordered models, but not high enough to explain our results, even after extrapolating to lower frequencies with a Boltzmann approach. Our results show that this material is more ordered than any Amorphous Silicon previously studied.
Christophe Ballif - One of the best experts on this subject based on the ideXlab platform.
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Amorphous Silicon oxide window layers for high efficiency Silicon heterojunction solar cells
Journal of Applied Physics, 2014Co-Authors: Johannes Peter Seif, Miha Filipic, Franc Smole, Antoine Descoeudres, Zachary C. Holman, Stefaan De Wolf, Marko Topič, Christophe BallifAbstract:In Amorphous/crystalline Silicon heterojunction solar cells, optical losses can be mitigated by replacing the Amorphous Silicon films by wider bandgap Amorphous Silicon oxide layers. In this article, we use stacks of intrinsic Amorphous Silicon and Amorphous Silicon oxide as front intrinsic buffer layers and show that this increases the short-circuit current density by up to 0.43 mA/cm2 due to less reflection and a higher transparency at short wavelengths. Additionally, high open-circuit voltages can be maintained, thanks to good interface passivation. However, we find that the gain in current is more than offset by losses in fill factor. Aided by device simulations, we link these losses to impeded carrier collection fundamentally caused by the increased valence band offset at the Amorphous/crystalline interface. Despite this, carrier extraction can be improved by raising the temperature; we find that cells with Amorphous Silicon oxide window layers show an even lower temperature coefficient than referenc...
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High-Efficiency Amorphous Silicon Solar Cell on a Periodic Nanocone Back Reflector
Advanced Energy Materials, 2012Co-Authors: Ching-mei Hsu, Celine Pahud, Franz-josef Haug, Zhichao Ruan, Corsin Battaglia, Christophe Ballif, Shanhui Fan, Yi CuiAbstract:An Amorphous Silicon solar cell on a periodic nanocone back reflector with a high 9.7% initial conversion efficiency is presented. The optimized back-reflector morphology provides powerful light trapping and enables excellent electrical cell performance. Up-scaling to industrial production of large-area modules should be possible using nanoimprint lithography.
Koeng Su Lim - One of the best experts on this subject based on the ideXlab platform.
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towards a high efficiency Amorphous Silicon solar cell using molybdenum oxide as a window layer instead of conventional p type Amorphous Silicon carbide
Applied Physics Letters, 2011Co-Authors: Sang Il Park, Seung Jae Baik, Liang Fang, Jinwan Jeon, Koeng Su LimAbstract:A thermally evaporated molybdenum oxide (MoO3) film was used as a window layer of a hydrogenated Amorphous Silicon (a-Si:H) solar cell instead of the conventional p-type hydrogenated Amorphous Silicon carbide (p-a-SiC:H) film. The short circuit current density (JSC) and fill factor were increased due to the wide optical band gap and high conductivity of the MoO3 film. As a result, the conversion efficiency of the fabricated MoO3 solar cell was increased to 6.21% compared to the typical a-Si:H solar cell (5.97%).
Yi Cui - One of the best experts on this subject based on the ideXlab platform.
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robustness of Amorphous Silicon during the initial lithiation delithiation cycle
Journal of Power Sources, 2014Co-Authors: Lucas A Berla, Yi Cui, Seok Woo Lee, Ill Ryu, W D NixAbstract:Abstract Recent research on the electrochemical lithiation of Amorphous Silicon nanoparticles shows that Amorphous Silicon is more fracture resistant than crystalline Silicon during lithiation. Nanoparticles of Amorphous Silicon can be lithiated and delithiated without any fracture at all. To fully exploit the potential of using Amorphous Silicon as electrodes for lithium ion batteries it is important to determine if larger, micron-sized, Amorphous Silicon structures can be lithiated and delithiated without fracture. Here we study the morphologies of initially Amorphous Silicon micropillars (∼2.3 μm tall) both before and after electrochemical lithiation and delithiation. No internal or external cohesive cracking is detected in lithiated pillars for any of the pillar sizes studied. Delithiated pillars exhibit some delamination at the interface between the pillar and the underlying nickel substrate. For larger diameter pillars, the initiated interfacial crack is driven upward into the delithiated pillar as the crack propagates radially inward. However, no cohesive fracture unrelated to interfacial cracking is seen in even the largest delithiated pillars. Finite element modeling provides support for the observation that the cohesive fracture resistance of Amorphous Silicon micropillars is representative of the fracture resistance of Amorphous Silicon microparticles of comparable dimensions.
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High-Efficiency Amorphous Silicon Solar Cell on a Periodic Nanocone Back Reflector
Advanced Energy Materials, 2012Co-Authors: Ching-mei Hsu, Celine Pahud, Franz-josef Haug, Zhichao Ruan, Corsin Battaglia, Christophe Ballif, Shanhui Fan, Yi CuiAbstract:An Amorphous Silicon solar cell on a periodic nanocone back reflector with a high 9.7% initial conversion efficiency is presented. The optimized back-reflector morphology provides powerful light trapping and enables excellent electrical cell performance. Up-scaling to industrial production of large-area modules should be possible using nanoimprint lithography.