Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Physical metallurgy of Ti–Ni-based shape memory alloys

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

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Photovoltaic Technology: The Case for Thin-Film Solar Cells

TCO and light trapping in silicon thin film solar cells

Intrinsic microcrystalline silicon: A new material for photovoltaics

The growth of microcrystalline silicon prepared by plasma-enhanced chemical vapour deposition depends on the deposition conditions and yields films with variable content of crystalline grains, amorphous network, grain boundaries and voids. The changes in the structural properties of a series of films grown under a variation of the dilution of the process gas silane in hydrogen, which induces a transition from highly crystalline to amorphous growth, were investigated. The evolution of the crystalline volume fraction was quantitatively analysed by Raman spectroscopy and X-ray diffraction. The results confirm the need for proper correction of the Raman data for optical absorption and Raman cross-section. Transmission electron microscopy was used to investigate the characteristics and the variation in the microstructure. Upon increasing the silane concentration the strong columnar growth with narrow grain boundaries degrades towards the growth of small irregularly shaped grains enclosed in an amorpho...

Structural properties of microcrystalline silicon in the transition from highly crystalline to amorphous growth

Hydrogenated microcrystalline silicon (μc-Si:H) thin-film solar cells were prepared at high rates by very high frequency plasma-enhanced chemical vapor deposition under high working pressure. The influence of deposition parameters on the deposition rate (RD) and the solar cell performance were comprehensively studied in this paper, as well as the structural, optical, and electrical properties of the resulting solar cells. Reactor-geometry adjustment was done to achieve a stable and homogeneous discharge under high pressure. Optimum solar cells are always found close to the transition from microcrystalline to amorphous growth, with a crystallinity of about 60%. At constant silane concentration, an increase in the discharge power did hardly increase the deposition rate, but did increase the crystallinity of the solar cells. This results in a shift of the μc-Si:H∕a-Si:H transition to higher silane concentration, and therefore leads to a higher RD for the optimum cells. On the other hand, an increase in the t...

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Microcrystalline silicon solar cells deposited at high rates

It is now generally recognized that the excitation frequency is an important parameter in radio‐frequency (rf) plasma‐assisted deposition. Very‐high‐frequency (VHF) silane plasmas (50–100 MHz) have been shown to produce high quality amorphous silicon films up to 20 A/s [H. Curtins, N. Wyrsch, M. Favre, and A. V. Shah, Plasma Chem. Plasma Processing 7, 267 (1987)], and therefore the aim of this work is to compare the VHF range with the 13.56 MHz industrial frequency in the same reactor. The principal diagnostics used are electrical measurements and a charge coupled device camera for spatially resolved plasma‐induced emission with Abel inversion of the plasma image. We present a comparative study of key discharge parameters such as deposition rates, plasma uniformity, ion impact energy, power transfer efficiency, and powder formation for the rf range 13–70 MHz.

/pdf/frequency-effects-in-silane-plasmas-for-plasma-enhanced-570xqzrtst.pdf

Frequency effects in silane plasmas for plasma enhanced chemical vapor deposition

The influence of the plasma excitation frequency on the growth conditions and the material properties of microcrystalline silicon prepared by plasma enhanced chemical vapor deposition at low deposition temperature is investigated. It is found that an increase of the plasma excitation frequency leads to a simultaneous increase of the growth rate, the grain size, and the Hall mobility of microcrystalline silicon. This is attributed to an effective selective etching of disordered material creating more space to develop crystalline grains, while also more species for faster growth of the crystallites are available.

/pdf/improvement-of-grain-size-and-deposition-rate-of-anhmbowfck.pdf

Friedhelm Finger

Papers

Intrinsic microcrystalline silicon: A new material for photovoltaics

Structural properties of microcrystalline silicon in the transition from highly crystalline to amorphous growth

Microcrystalline silicon solar cells deposited at high rates

Frequency effects in silane plasmas for plasma enhanced chemical vapor deposition

Improvement of grain size and deposition rate of microcrystalline silicon by use of very high frequency glow discharge