135 research outputs found
Elements of Good Training in Anatomic Pathology
The American College of Veterinary Pathologistsâ (ACVPâs) 2007â2012 strategic plan recognized the crisis confronting academic training programs and formed a task force to address these concerns. One area of concern identified by the ACVP Training Program Development Task Force was the lack of guidelines to make training more consistent across all programs and provide justification for maintaining or increasing faculty numbers and training resources. Training guidelines for clinical pathology have been outlined in three publications.1,2,4 The current document addresses the need for training guidelines in veterinary anatomic pathology
Grain Size and Texture of Cu2ZnSnS4 Thin Films Synthesized by Cosputtering Binary Sulfides and Annealing: Effects of Processing Conditions and Sodium
We investigate the synthesis of kesterite Cu2ZnSnS4 (CZTS) polycrystalline
thin films using cosputtering from binary sulfide targets followed by annealing
in sulfur vapor at 500 {\deg}C to 650 {\deg}C. The films are the kesterite CZTS
phase as indicated by x-ray diffraction, Raman scattering, and optical
absorption measurements. The films exhibit (112) fiber texture and preferred
low-angle and Sigma3 grain boundary populations which have been demonstrated to
reduce recombination in Cu(In,Ga)Se2 and CdTe films. The grain growth kinetics
are investigated as functions of temperature and the addition of Na.
Significantly, lateral grain sizes above 1 um are demonstrated for samples
grown on Na-free glass,demonstrating the feasibility for CZTS growth on
substrates other than soda lime glass
Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells
Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have
exhibited remarkable performance in solar cells, despite having non-negligible density of
defect states. A likely candidate is halide vacancies within the perovskite crystals, or the
presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which
could evolve during crystallization. Herein, we show that the addition of hypophosphorous
acid (HPA) in the precursor solution can significantly improve the film quality, both
electronically and topologically, and enhance the photoluminescence intensity, which leads to
more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can
reduce the oxidized I2 back into Iïżœ, and our results indicate that this facilitates an improved
stoichiometry in the perovskite crystal and a reduced density of metallic lead
Structural and chemical investigations of CBD- and PVD-CdS buffer layers and interface in Cu(In,Ga)Se2-based thin film solar cells.
It is known that high-efficiency thin film solar cells based on Cu(In,Ga)Se-2 (CIGS) can be obtained using US buffer layers grown by chemical bath deposition (CBD). The highest efficiencies achieved with US buffer layers produced by physical vapor deposition (PVD) are significantly lower. To find reasons for this difference, structural and chemical properties of CBD- and PVD-CdS buffer layers and their interfaces with CIGS were investigated by means of bright-field (BF-TEM), high-resolution (HR-TEM) and energy-filtered transmission electron microscopy (EF-TEM), and also by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). PVD-CdS grains were shown to be clearly larger than the CBD-CdS grains. Also, a large defect density was detected at the PVD-CdS/CIGS interface, which is attributed to the larger lattice mismatch than at the CBD-CdS/CIGS interface. Cu diffusion from CIGS into CdS was found for the CBD- and the PVD-CdS sample. The PVD-CdS/CIGS interface turned out to be quite abrupt, whereas the CBD-CdS/CIGS interface is rather diffuse. The differences in efficiencies of solar cells with CBD- and PVD-CdS buffer layers can partly be explained by referring to the higher defect density and the probable absence of an inversion of the near-interface region from p- to n-type at the PVD-CdS/CIGS interface
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