Laser-Induced Breakdown Spectroscopy (LIBS) of silicon was performed using a nanosecond pulsed frequency doubled Nd:YAG (532 nm) laser. The temporal evolution of the laser ablation plumes was characterized under a range of low pressures. Electron densities were determined from the Stark broadening of the Si (I) 288.16 nm emission line and were found to be in the range 2.79 × 10 16 cm-3 to 5.59 × 10 19 cm-3. Excitation temperatures of 9000-21000 K were calculated using the Si (I) 288.16 nm emission line to continuum ratio. The morphology of the laser plume, observed with respect to time, was seen to be strongly dependent on the ambient pressure. The density and temperature of the plasma was also found to vary critically with plasma morphology. Three ambient pressure regimes were identified where the plasma evolution was observed to differ markedly. Requirements for the existence of local thermal equilibrium conditions in the laser-induced plasmas are discussed with respect to these results.

Response Surface Methodology (RSM) was employed to optimise LIBS analysis of single crystal silicon at atmospheric pressure and under vacuum conditions (pressure ~10 -6 mbar). Multivariate analysis software (StatGraphics 5.1) was used to design and analyse several multi-level, full factorial RSM experiments. A Quality Factor (QF) was conceived as the response parameter for the experiments, representing the quality of the LIBS spectrum captured for a given hardware configuration. The QF enabled the hardware configuration to be adjusted so that a best compromise between resolution, signal intensity and signal noise could be achieved. The effect on the QF of 1 simultaneously adjusting spectrometer gain, gate delay, gate width, lens position and spectrometer slit width was investigated, and the conditions yielding the best QF determined.

Abstract:Laser-Induced Breakdown Spectroscopy (LIBS) was applied to the analysis of bioceramic samples. The relationship between sample hardness and LIBS plasma properties was investigated, with comparison to conventional Vickers hardness measurements. The plasma excitation temperature T e was determined using the lineto-continuum ratio for the Si (I) 288.16 nm emission line; we have demonstrated a linear relationship between sample surface hardness and plasma temperature. Results indicate that hardness determination based on measurements of T e offers greater reproducibility than Vickers hardness measurements, under the conditions considered here. The validity of spectroscopic diagnostics based on LTE was confirmed.

Laser-Induced Breakdown Spectroscopy of silicon was performed using a nanosecond pulsed frequency doubled Nd:YAG (532 nm) laser. The temporal evolution of the laser ablation plumes in air at atmospheric pressure and at an ambient pressure of

This paper reports the production of high quality copper indium diselenide thin films using pulsed DC magnetron sputtering from a powder target. As grown thin films consisted of pinhole free, densely packed grains. X ray diffraction showed that films were highly orientated in the (112) and/or (204)/(220) direction with no secondary phases present. The most surprising and exciting outcome of this study was that the as-grown films were of near stoichiometric composition, almost independent of the composition of the starting material.No additional steps or substrate heating were necessary to incorporate selenium and create single phase CuInSe 2 . Electrical properties obtained by hot point probe and four point probe gave values of low resistivity and showed that the films were all p type. The physical and structural properties of these films were analyzed using x-ray diffraction, scanning electron microscopy and atomic force microscopy. Resistivity measurements were carried out using the four point probe and hot probe methods. The single step deposition process can cut down the cost of the complex multi step processes involved in the traditional vacuum based deposition techniques. KeywordsCuInSe 2 thin films, pulsed DC magnetron sputtering, stoichiometric CuInSe 2 films, photovoltaic, solar cells, single step CuInSe 2 films.