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

第12次 아시아ㆍ太平洋 矯政局長會議 參加記

Piezoelectric materials play a crucial role in a large number of devices and applications modern society would not like to miss. Mobile phones and ultrasonic imaging are just the most prominent ones. Since two decades, miniaturization of mechanical devices in silicon technology is a major research direction in engineering known under name of MEMS, which stands for micro-electro-mechanical systems. Piezoelectricity fits very well into this concept and was expected right from the beginning to play its role in MEMS. The breakthrough was made with RF filters in mobile phones working on the principle of standing thickness waves in AlN films. What counts here is acoustic quality and stability. The force champion among piezoelectric thin film materials, Pb(Zr,Ti)O3 gave more problems in processing, and requires more patience to meet requirements and needs for a mass applications. It seems, however, that the breakthrough is imminent. This article attempts to give an overview of the field, highlighting recent achievements, introduce operation principles, and describe some applications.

Recent Progress in Materials Issues for Piezoelectric MEMS

Solar-blind ultraviolet (UV) photodetectors (PDs) have attracted tremendous attention in the environmental, industrial, military, and biological fields. As a representative III-nitride material, AlGaN alloys have broad development prospects in the field of solar-blind detection due to their superior properties, such as tunable wide bandgaps for intrinsic UV detection. In recent decades, a variety of AlGaN-based PDs have been developed to achieve high-precision solar-blind UV detection. As integrated optoelectronic technology advances, AlGaN-based focal plane arrays (FPAs) are manufactured and exhibit outstanding solar-blind imaging capability. Considering the rapid development of AlGaN detection techniques, this paper comprehensively reviews the progress on AlGaN-based solar-blind UV PDs and FPAs. First, the basic physical properties of AlGaN are presented. The epitaxy and p-type doping problems of AlGaN alloys are then discussed. Diverse PDs, including photoconductors and Schottky, metal–semiconductor–metal (MSM), p-i-n, and avalanche photodiodes (APDs), are demonstrated, and the physical mechanisms are analyzed to improve device performance. Additionally, this paper summarizes imaging technologies used with AlGaN FPAs in recent years. Benefiting from the development of AlGaN materials and optoelectronic devices, solar-blind UV detection technology is greeted with significant revolutions. Summarizing recent advances in the processing and properties of AlGaN-based solar-blind UV photodetectors and focal plane arrays as well as AlGaN growth and doping techniques.

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Progress on AlGaN-based solar-blind ultraviolet photodetectors and focal plane arrays.

An overview is given on nucleation phenomena of Pb(Zr,Ti)O3 (PZT) thin films on Pt(111)-based substrates. Emphasis is given on in situ growth methods, particularly in situ reactive sputtering from three metallic targets. Growth of PZT thin films is discussed from the point of view of the PbOx–TiO2 phase diagram, PbO vapor pressure, and classical nucleation theory. The role of thin TiO2 affinity layers and spots is explained in the frame of this theory. Activation energies for desorption and chemisorption are adapted to comply with the fact that nucleation rates on TiO2 are much larger than the ones on bare Pt(111). The model reproduces well the PbO surface flux from bare Pt(111) to the affinity spots in the case of PbTiO3 nucleation and the reversed tendency in the case of PZT 40∕60 nucleation, explaining experimental observations. The critical size of nuclei was calculated to contain 8–10unit cells for PbTiO3∕Pt nucleation and 14–17 for PZT/Pt nucleation.

Texture control and seeded nucleation of nanosize structures of ferroelectric thin films

Perovskite lead scandium tantalate (PST){emdash}PbSc{sub 1/2}Ta{sub 1/2}O{sub 3}{emdash}thin films have been prepared from lead-rich targets by rf magnetron sputtering onto a variety of substrates (e.g., MgO-on-sapphire and platinized silicon). Detailed microstructural chemical analysis of the films using transmission electron microscopy and energy dispersive x-ray spectroscopy techniques showed that they contained large amounts of excess lead, ranging from 7 to over 70 at.{percent} and that this was located within the crystallite grains making up the films rather than solely at grain boundaries. Measurement of the lattice parameters of the films using x-ray diffraction and using the underlying materials as internal standards have shown that the lattice parameters of the films are consistently larger than those for bulk PST. Comparison of the film lattice parameters with composition and with the lattice parameter/composition trend of a large number of lead containing perovskites strongly suggests that the excess lead is present on the B sites of the structure as Pb{sup 4+}. The consequences for this on the structural and electrical properties of these films and PST films deposited by other workers are discussed. {copyright} {ital 1997 American Institute of Physics.}

Sputtered lead scandium tantalate thin films: Pb4+ in B sites in the perovskite structure

Lanthanum nickelate layers have been deposited onto 100 mm diameter silicon/silicon dioxide and (0001) sapphire substrates by liquid-delivery metal-organic (MO) CVD using the precursors La(thd) 3 and Ni(thd) 2 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) dissolved in tetrahydrofuran and heptane. The LaNiO 3 (LNO) was deposited at 630°C in an oxidizing atmosphere, and the as-grown layers were highly crystalline and highly (110)-oriented on Si/SiO 2 . Electrical resistivity studies were performed and showed a dependence on the La/Ni ratio, the substrate used, and the post-deposition annealing conditions. A minimum electrical resistivity value of 300 μΩ cm was measured for LNO deposited on (0001) sapphire and rapidly annealed at 750°C. The resistivity values of the LNO layers deposited onto silicon/silicon dioxide were higher, with a minimum value of 1 mΩ cm. The rapid annealing at 750 °C resulted in cracking of some of the LNO layers deposited onto the silicon substrates. However, the layers that were nickel-rich withstood the annealing treatment better and showed little evidence of cracking.

The Metal–Organic Chemical Vapor Deposition of Lanthanum Nickelate Electrodes for Use in Ferroelectric Devices

An earlier paper [1] discussed the merits of adaptive coded apertures for use as lensless imaging systems in the thermal
infrared and visible It was shown how diffractive (rather than the more conventional geometric) coding could be used,
and that 2D intensity measurements from multiple mask patterns could be combined and decoded to yield enhanced
imagery Initial experimental results in the visible band were presented Unfortunately, radiosity calculations, also
presented in that paper, indicated that the signal to noise performance of systems using this approach was likely to be
compromised, especially in the infrared
This paper will discuss how such limitations can be overcome, and some of the tradeoffs involved Experimental results
showing tracking and imaging performance of these modified, diffractive, adaptive coded aperture systems in the visible
and infrared will be presented The subpixel imaging and tracking performance is compared to that of conventional
imaging systems and shown to be superior System size, weight and cost calculations indicate that the coded aperture
approach, employing novel photonic MOEMS micro-shutter architectures, has significant merits for a given level of
performance in the MWIR when compared to more conventional imaging approaches

Adaptive coded aperture imaging in the infrared: towards a practical implementation

Lead scandium tantalate (PST) thin films have been deposited on a platinized silicon substrate with and without a buffer layer of MgO at the temperature of 525°C It was found that PST films on the substrate without a buffer layer were strongly (1 1 1) oriented perovskite, whilst films on the substrate with a buffer layer showed the presence of second-phase pyrochlore, and the films were (1 1 1) and (1 1 0) oriented These structural differences were believed to result from the structural differences between the platinum layers immediately below the respective PST layers The “lines” which divide PST into “network” of islands were found to be no more than wider grain boundaries, rather than “cracks” as believed previously Micro-beam diffraction and energy dispersive X-ray analysis showed that grain boundaries were tantalum-rich and lead-deficient compared to perovskite grain centres Electrical properties, such as relative permittivity and dielectric loss, for the films were also measured

Sputtered lead scandium tantalate thin films : a microstructural study

Excimer laser annealing has been used to convert low temperature (non-ferroelectric) deposited lead zirconate titanate (PZT) to the perovskite phase without significantly heating underlying layers. A pulse-extension technique has been used to lengthen the laser pulse duration from 25 ns to 374 ns, lowering the surface temperature and improving the heat distribution in the PZT, as compared to the non-extended case, but still not significantly heating the substrate. Initial experiments are reported which have shown the technique to be capable of crystallising over half a 500 nm thick PZT film to perovskite although a melting effect limited the converted thickness. The thickness crystallised is however of the order of that used in FeRAM devices and modelled temperature profiles suggest that the technique provides a tractable solution for high temperature processing of ferroelectric thin films of thickness 200-300 nm on low thermal budget substrates.

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M. A. Todd

Papers

Sputtered lead scandium tantalate thin films: Pb4+ in B sites in the perovskite structure

The Metal–Organic Chemical Vapor Deposition of Lanthanum Nickelate Electrodes for Use in Ferroelectric Devices

Adaptive coded aperture imaging in the infrared: towards a practical implementation

Sputtered lead scandium tantalate thin films : a microstructural study

Pulse-Extended Excimer Laser Crystallisation of Pb(Zr,Ti)O 3 Thin Films for Integration on Low Thermal Budget Substrates