Combined in-depth scanning Auger microscopy and Raman scattering characterisation of CuInS2 polycrystalline films

ArticleinVacuum 63(1):315-321 · July 2001with4 Reads
DOI: 10.1016/S0042-207X(01)00207-X
In this work, the combination of in-depth scanning Auger microscopy with Raman microprobe spectroscopy is applied for the detailed microstructural characterisation of CuInS2 (CIS) thin films. CIS films are used for the fabrication of high efficiency solar cell devices. These films are obtained by sequential sputtering of Cu and In layers on a Mo-coated glass substrate, followed by a sulphurisation step at 500°C in a rapid thermal processing furnace. In order to study this process, samples obtained at intermediate steps are investigated. The obtained data show the formation of the CIS phase already at the first stages of the sulphurisation process, although with a highly disordered structure. Moreover, segregation of CuS towards the surface is observed before sulphurisation is completed. This fact is accompanied by a significant increase of the structural quality of the CIS film, which allows for the fabrication of high efficiency solar cell devices. The performed analysis corroborates the strong complementarity between the used techniques for the detailed microstructural analysis of complex multilayer systems.
    • "1). Elemental analysis was performed by focusing the nanoprobe on a specific target site on the sample which was bombarded with electrons resulting in the release of Auger electrons giving a specific energy profile [66]. These profiles were specific for every element and due to all elements having a unique set of electronbinding energies, the unknown elements in the sample could be identified [67]. "
    [Show abstract] [Hide abstract] ABSTRACT: Control of bacterial diseases has, for many years, been dependent on the use of antibiotics. Due to the high levels of efficacy of antibiotics in the past other disease control options have, to a large extent, been neglected. Mankind is now facing an increasing problem with antibiotic resistance. In an effort to retain some antibiotics for human use, there are moves afoot to limit or even ban the use of antibiotics in animal production. The use of antibiotics as growth promoters have been banned in the European Union and the USA. The potential ban on the use of antibiotics to treat diseases in production animals creates a dilemma for man-suffer significant problem with bacterial infection or suffer from a severe shortage of food! There are other options for the control of bacterial diseases. These include vaccine development, bacteriophage therapy, and improved biosecurity. Vaccine development against bacterial pathogens, particularly opportunistic pathogens, is often very challenging, as in many cases the molecular basis of the virulence is not always clearly understood. This is particularly true for Escherichia coli. Biosecurity (disinfection) has been a highly neglected area in disease control. With the ever-increasing problems with antibiotic resistance-the focus should return to improvements in biosecurity. As with antibiotics, bacteria also have mechanisms for resistance to disinfectants. To ensure that we do not replace one set of problems (increasing antibiotic resistance) with another (increasing resistance to disinfectants) we need to fully understand the modes of action of disinfectants and how the bacteria develop resistance to these disinfectants. Molecular studies have been undertaken to relate the presence of QAC resistance genes in bacteria to their levels of sensitivity to different generations of QAC-based products. The mode of action of QAC on bacteria has been studied using NanoSAM technology, where it was revealed that the QAC causes disruption of the bacterial cell wall and leaking of the cytoplasm out of the cells. Our main focus is on the control of bacterial and viral diseases in the poultry industry in a post-antibiotic era, but the principles remain similar for disease control in any veterinary field as well as in human medicine.
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    [Show abstract] [Hide abstract] ABSTRACT: Enlargement of bacterial cells during bacteriophage replication has been observed in the past with T-even, Lambda and N4 bacteriophages by the use of transmission electron microscopy (TEM) and light microscopy techniques and hypotheses explaining the enlargement of bacteriophage-infected cells have been postulated in literature. In this study, enlarged Escherichia coli cells were observed using scanning electron microscopy (SEM) after 45 min of a P4-like bacteriophage infection. These bacteria were also studied using scanning auger microscopy (SAM) in combination with an Argon-ion gun by which the bacteria were etched. Neither SEM nor SAM have been used during the analysis of bacteriophage infected enlarged host cells, making this study unique. The use of SAM on bacteriophage-related investigations is also novel. Small phage-like particles were observed inside the etched enlarged and etched normal bacteriophage-exposed host cells. The presence of bacteriophage-like particles inside both types of cells confirmed that the enlarged cells, which were scarce in this sample, were not artifacts of some kind such as contamination by other microorganisms. The enlargement of bacteriophage infected host cells coincides with previous studies reported in literature, but never before with P4-like bacteriophages.
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    • "SAM is a powerful tool used in the semi-quantitative elemental analysis on extremely small samples and is usually used for the near-surface analysis of conductor and semiconductors while the sample is visualised by Scanning Electron Microscopy (SEM) (Calvo-Barrio et al., 2001; Hochella et al., 1986). SAM has also been used to perform in-depth studies where the Argon (Ar + ) ion gun has been used for targeted etching on materials such as semi-conductors (Calvo-Barrio et al., 2001). The Ar + gun was used to etch through the sample in nanometer thick segments while the SAM and SEM modes were applied to analyse and visualise the elemental composition and 3D ultrastucture of the surface of the cells respectively. "
    [Show abstract] [Hide abstract] ABSTRACT: Didecyldimethylammonium chloride (DDAC) is a Quaternary Ammonium Compound (QAC) disinfectant often used in the poultry industry to disinfect hard surfaces. DDAC is a membrane active agent and causes the leakage of important intracellular material. Understanding the mode of action and possible resistance is important; in particular, the pending post antibiotic era that the poultry industry is facing. Staphylococcus aureus strain ATCC2357 treaded with DDAC revealed protruberances or bleb formations on their cell walls when observed with scanning electron microscopy. The DDAC treated cells were further investigated using NanoSAM. This technology showed morphological changes as well as structural detail on control cells caused by the disinfectant that scanning electron microscopy could not. NanoSAM also showed a decrease in the elemental intensities during the etching of the cells treated with QAC. This proved that QAC leads to the leakage of cellular material.
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