145 research outputs found
Policing the Global Economy: The Threat to Private Enterprise
International organizations are becoming increasingly involved in the regulation of private enterprise. Advocates of this type of regulation seem to have overlooked the shortcomings of existing regulation of business. Ultimately, it is the consumer who bears the burden that government imposes on business.https://openscholarship.wustl.edu/mlw_papers/1060/thumbnail.jp
Experimental quantification of useful and parasitic absorption of light in plasmon-enhanced thin silicon films for solar cells application
A combination of photocurrent and photothermal spectroscopic techniques is applied to experimentally quantify the useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (ÎĽc-Si:H) films incorporating optimized metal nanoparticle arrays, located at the rear surface, for improved light trapping via resonant plasmonic scattering. The photothermal technique accounts for the total absorptance and the photocurrent signal accounts only for the photons absorbed in the ÎĽc-Si:H layer (useful absorptance); therefore, the method allows for independent quantification of the useful and parasitic absorptance of the plasmonic (or any other) light trapping structure. We demonstrate that with a 0.9 ÎĽm thick absorber layer the optical losses related to the plasmonic light trapping in the whole structure are insignificant below 730 nm, above which they increase rapidly with increasing illumination wavelength. An average useful absorption of 43% and an average parasitic absorption of 19% over 400-1100 nm wavelength range is measured for ÎĽc-Si:H films deposited on optimized self-assembled Ag nanoparticles coupled with a flat mirror (plasmonic back reflector). For this sample, we demonstrate a significant broadband enhancement of the useful absorption resulting in the achievement of 91% of the maximum theoretical Lambertian limit of absorption
Optical absorption and light scattering in microcrystalline silicon thin films and solar cells
Optical and Electrical Properties of Undoped Microcrystalline Silicon Deposited by the VHF-GD with Different Dilutions of Silane in Hydrogen
Impact of AFM-induced nano-pits in a-Si:H films on silicon crystal growth
Conductive tips in atomic force microscopy (AFM) can be used to localize field-enhanced metal-induced solid-phase crystallization (FE-MISPC) of amorphous silicon (a-Si:H) at room temperature down to nanoscale dimensions. In this article, the authors show that such local modifications can be used to selectively induce further localized growth of silicon nanocrystals. First, a-Si:H films by plasma-enhanced chemical vapor deposition on nickel/glass substrates are prepared. After the FE-MISPC process, yielding both conductive and non-conductive nano-pits in the films, the second silicon layer at the boundary condition of amorphous and microcrystalline growth is deposited. Comparing AFM morphology and current-sensing AFM data on the first and second layers, it is observed that the second deposition changes the morphology and increases the local conductivity of FE-MISPC-induced pits by up to an order of magnitude irrespective of their prior conductivity. This is attributed to the silicon nanocrystals (<100 nm) that tend to nucleate and grow inside the pits. This is also supported by micro-Raman spectroscopy
Assessment of immune functions and MRI disease activity in relapsing-remitting multiple sclerosis patients switching from natalizumab to fingolimod (ToFingo-Successor)
Influence of substrate on the microstructure of microcrystalline silicon layers and cells
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