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XPS characterization of dilute nitride indium gallium arsinide materials nanoporous silica for active sampling of aldehydes

Scudder, Samantha

Multi-junction solar cells have been of recent interest due to their ability to achieve efficiencies as high as 50%. When small amounts of nitrogen are incorporated into the lattice, material quality problems can arise with the formation of Ga-N and Ga-In-N defects. The creation of nonradiative centers, and a decrease in homogeneity results in lower efficiencies. Annealing these solar cells in a nitrogen-rich environment can facilitate the rearrangement to the favorable In-N configuration. X-ray photoelectron spectroscopy was used to characterize these binding configurations to determine if these defects were passivated after annealing and hydrogenation treatments. The nitrogen associated region was studied, illuminating details that have not been seen previously. A second project investigated methods to look at natural or anthropogenic sources of air pollution. Among various indoor air pollutants, low molecular weight aldehydes (formaldehyde and acetaldehyde) have become an important class of volatile organic compounds because of their classification as known or probable human carcinogens. A nanoporous silica sorbent, named OSU-6, was explored in this study for its use in aldehyde sampling with subsequent thermal desorption and gas chromatography/mass spectrometry analysis. A series of analyses were performed to determine the materials sorption capacity in a variety of sampling conditions.