Raman Studies Of Heavily Implanted, Dye-laser-annealed GaAs

Raman scattering is used to study the annealing behavior produced by 10 nsec, 565 nm dye laser pulses in high dose ion-implanted GaAs. Samples were prepared with Sn and Cd implantations of 2, 5, and 10 x 1015 cm2. The Raman spectra indicate that the threshold for epitaxial growth lies between 0.2 - 0.3 J cm2. Best carrier activation (∼ 2%), however, is achieved at ∼1.6 J cm2 for the Sn-implanted sample (n-type). For Cd implantation the electrical activation appears to be very high ({greater-than or approximate} 50%) for low pulse energies({less-than or approximate} 0.3 J cm2) but decreases for higher pulse energies. © 1985

Fabrication and Physics of CdTe Devices by Sputtering: Final Report, 1 March 2005 - 30 November 2008

Work to understand CdS/CdTe solar cell device physics; increase magnetron sputtering rate (while keeping high device quality); reduce thickness of CdTe layers (while keeping voltage and fill factor)

Sputtered II-VI Alloys and Structures forTandem PV: Final Subcontract Report, 9 December 2003 - 30 July 2007

This report elaborates on Phase 3 and provides summaries of the first two Phases. Phase 3 research work was divided into five task areas covering different aspects of the II-VI tandem cell

An Apparatus to Control and Monitor the Para-D2 Concentration in a Solid Deuterium, Superthermal Source of Ultra-cold Neutrons

Controlling and measuring the concentration of para-D2 is an essential step toward realizing solid deuterium as an intense ultra-cold neutron (UCN) source. To this end, we implemented an experimental technique to convert para- to ortho-deuterium molecules by flowing D2 gas through a cryogenic cell filled with paramagnetic hydrous ferric oxide granules. This process efficiently reduced the para-D2 concentration from 33.3% to 1.5%. Rotational Raman spectroscopy was applied to measure the residual para-D2 contamination to better than 2 parts in 10^3, and the hydrogen contamination to 1 part in 10^3. We also contrast our optical technique to conventional thermal conductivity measurements of the para-D2 concentration, reporting some of the relevant strengths and weaknesses of our implementation of each technique.Comment: accepted for publication in NIM

The Gauteng conservation plan : planning for biodiversity in a rapidly urbanising province

BACKGROUND : Gauteng, the smallest of South Africa’s nine provinces, is rich in biodiversity; yet it is also the most densely populated province and thus faces significant development pressures. OBJECTIVE : A project was therefore initiated in 2001 to identify areas of biodiversity importance in the province, using the systematic spatial biodiversity planning approach that has been adopted in South Africa. This article reports on the final version of the provincial conservation plan as completed in 2011. METHOD : Vegetation types and quaternary catchments constituted the coarse filter biodiversity features, while rare and threatened taxa constituted the fine filter features. Ecological processes were captured by a range of landscape features, while planning for climate change primarily involved the design of a corridor network. Planning was undertaken within the ArcView linked C-plan decision support system, where a cost surface preferentially directed the selection of available sites towards low-cost areas. RESULTS : Forty-four per cent of the province is required to achieve targets. Only 8% of features are close to having their targets met or are adequately conserved in the current protected area network of 23 protected areas covering 2.4% of the province, while 73% of features are absent or poorly represented. CONCLUSION : The existing protected area network is inadequate for the conservation of biodiversity in Gauteng. The Gauteng Conservation Plan identifies a set of areas that are required to achieve conservation targets. It is important that identified areas currently not in the protected area network are protected either formally or through legislated land use management processes.http://www.abcjournal.orgam2018Zoology and Entomolog

High-Efficiency Thin-Film Cadmium Telluride Photovoltaic Cells; Final Subcontract Report, Final Technical Report, 21 January 1994-31 March 1998

This report describes work performed during the past year by The University of Toledo photovoltaics group. Researchers continued to develop rf sputtering for CdS/CdTe thin-film solar cells and to optimize the post-deposition process steps to match the characteristics of the sputtering process. During the fourth phase of the present contract, we focused on determining factors that limit the efficiency in our ''all-sputtered'' thin-film CdTe solar cells on soda-lime glass. These issues include controlling CdS/CdTe interdiffusion, understanding the properties of the CdS{sub x}Te{sub 1-x} alloy, optimizing process conditions for CdCl{sub 2} treatments, manipulating the influence of ion bombardment during rf sputtering, and understanding the role of copper in quenching photoluminescence and carrier lifetimes in CdTe. To better understand the important CdS/CdTe interdiffusion process, we have continued our collaboration with the University at Buffalo and Brookhaven National Synchrotron Light Source in measurements using grazing-incidence X-rays. Interdiffusion results in the formation of the ternary alloy material CdS{sub x}Te{sub 1-x} at or near the heterojunction, where its properties are critical to the operation of the solar cell. We have placed significant effort on characterizing this alloy, an effort begun in the last phase. A complete set of films spanning the alloy range, prepared by pulsed-laser deposition, has now been characterized by wavelength dispersive X-ray spectroscopy and optical absorption at NREL; by Raman scattering, X-ray diffraction, and electrical measurements in our lab; and by spectroscopic ellipsometry at Brooklyn College. We continued to participate in cooperative activity with the CdTe National Team. We prepared a series of depositions on borosilicate glass substrates having doped SnO{sub 2} layers coated with TiO{sub 2} (prepared by the University of South Florida and Harvard) and similar substrates having a resistive SnO{sub 2} layer on the doped tin oxide (fabricated by Golden Photon). The Golden Photon high-resistivity SnO{sub 2} structure yielded excellent cell performance