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

Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success...

/pdf/high-k-gate-dielectrics-current-status-and-materials-zjvba0c4u8.pdf

High-κ gate dielectrics: Current status and materials properties considerations

Phase-change materials are some of the most promising materials for data-storage applications. They are already used in rewriteable optical data storage and offer great potential as an emerging non-volatile electronic memory. This review looks at the unique property combination that characterizes phase-change materials. The crystalline state often shows an octahedral-like atomic arrangement, frequently accompanied by pronounced lattice distortions and huge vacancy concentrations. This can be attributed to the chemical bonding in phase-change alloys, which is promoted by p-orbitals. From this insight, phase-change alloys with desired properties can be designed. This is demonstrated for the optical properties of phase-change alloys, in particular the contrast between the amorphous and crystalline states. The origin of the fast crystallization kinetics is also discussed.

Phase-change materials for rewriteable data storage

At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of ≅ 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of ≅ 10 nanometers.

/pdf/superconducting-interfaces-between-insulating-oxides-21qkm7ai8t.pdf

Superconducting Interfaces Between Insulating Oxides

Raman spectroscopy is a standard characterization technique for any carbon system. Here we review the Raman spectra of amorphous, nanostructured, diamond-like carbon and nanodiamond. We show how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen. The measured spectra change with varying excitation energy. By visible and ultraviolet excitation measurements, the G peak dispersion can be derived and correlated with key parameters, such as density, sp(3) content, elastic constants and chemical composition. We then discuss the assignment of the peaks at 1150 and 1480 cm(-1) often observed in nanodiamond. We review the resonant Raman, isotope substitution and annealing experiments, which lead to the assignment of these peaks to trans-polyacetylene.

Raman spectroscopy of amorphous, nanostructured, diamond-like carbon, and nanodiamond

There are many applications for nanocrystalline thin films in optical devices that require isotropic optical properties. A novel way to obtain these isotropic properties for the index of refraction and/or optical absorption constant, etc., and at the same time to minimize microscopic strain is presented in this article. This approach is based on strain reduction mechanisms that occur in the intermediate phases, IPs, of non-crystalline glasses and thin films. In these compositional regimes, either site percolation, or volume percolation, each above an applicable critical value, provides a quantitative understanding of the microscopic bonding arrangements associated with strain-reducing chemical bonding self-organizations. A similar framework, presented for the first time in this article, develops a microscopic understanding of macroscopic strain reduction in several different phase-separated composites. This understanding has emerged from focussed research on qualitatively different hetero-structure device structure constituents, e.g.; (i) high-k replacement dielectrics for SiO z in field effect transistors gate stacks for ad - vanced semiconductor devices, and (ii) active and passive thin films for optically switched memory cells. In each instance strain reduction and its intrinsic relationship to low densities of defects and defect precursors has provided a driving force in the identification of a narrow range of compositions that satisfy technological needs.

Controlled chemical phase separation in binary and ternary composites: A pathway to isotropic optical and electrical behavior for device applications

H/D-, N-H/D- and Si-H/D-bond density changes were investigated in stacks consisting of a Cz-Si substrate, a thin layer of SiO2, amorphous deuterated silicon nitride as well as amorphous hydrogenated silicon nitride in order to see if the post deposition anneal of a-SixNyHz layers on crystalline silicon wafers can actually lead to a migration of H atoms into the Si-bulk, which is an important question in regard to emitter passivation of Si-solar cells. The stacks were grown with remote plasma enhanced chemical vapor deposition (RPECVD). A low temperature (≈200°C) process of down stream injected ammonia (NH3) and silane (SiH4) activated by an upstream injected He-plasma, prod]ced through RF-radiation (13.65MHz) was used. Thermal treatment was executed by ex situ rapid thermal anneal in Ar ambient. For the measurements of H and D bond densities, FTIR was employed while SIMS determined atomic densities of H, D and O in the c-Si/nitride interface region. The experiments showed that H transport in silicon nitride is determined by several mechanisms including diffusion and dissociation processes and that silicon nitride deposited with high ammonia to silane ratios can prod]ce molecular species like ammonia and H2. The study of the reaction dynamics showed that the prod]ction of molecular hydrogen is the most dominant process as long as Si-H-bonds are present in the system. After their exhaustion, an ammonia prod]cing reaction prevails that leads with increasing temperatures to lower densities in the nitride films.

Diffusion of hydrogen and deuterium in stack systems of SixNyHz/ SixNyDz and crystalline Si

Mesarjian et al. were the first to recognize the effects of suboxide interfacial transition regions at Si-SiO2 interfaces on tunneling oscillations in the Fowler-Nordheim regime. This paper extends these ideas to the direct tunneling regime and focuses on differences in interfacial transition regions between Si-SO2 interfaces with, and without monolayer level interface nitridation. Tunneling currents in both the direct and Fowler-Nordheim tunneling regimes are reduced by monolayer level interface nitridation for PMOS and NMOS devices with the same oxide-equivalent thickness. This paper develops a modified barrier layer model based on analysis of XPS results that accounts for these reductions in current in the direct tunneling regime.

The Effects of Interfacial Suboxide Transition Regions on Direct Tunneling in Oxide and Stacked Oxide-Nitride Gate Dielectrics

Extended X-ray absorption fine structure (EXAFS) studies of as-deposited Ge2Sb2Te5 films yield Ge K edge spectra essentially the same as previously reported; however, these earlier studies assumed only Te nearest neighbors, but the comprehensive analysis of this paper indicates significant concentrations of both Ge–Ge and Ge–Te bonds. Average bond coordination and number of valence bonding constraints/atom have been determined from an extension of bond-constraint theory that includes broken bond-bending constraints for Ge–Ge bonds, and optical memory alloys on the Sb2Te3–GeTe tie-line ∼3.05 ± 0.05 bonding constraints/atom, consistent with formation of an intermediate phase. The fraction of threefold or over-coordinated Te increases from 7.1 to 25% along this tie-line, and the amorphous to crystalline optical transmissivity transition occurs over a narrow temperature range, <10 °C. Over-coordination and Te leads to formation of positively charged defects, which must be balanced by under-coordinated of negatively charged Sb or Ge defect bonding arrangements.

Local Bonding Arrangements in Amorphous Ge2Sb2Te5: The Importance of GE and TE Bonding

Based on spectroscopic studies, and guided by ab initio theory, the electron and hole traps in HfO2 and other transition metal elemental oxides e.g., TiO2, are assigned to O‐atom divacancies, clustered at internal grain boundaries. Engineering solutions for defect reduction are identified: i) deposition of ultra‐thin, < 2 nm HfO2 and phase separated Hf silicate dielectrics, in which grain boundary formation is suppressed by effectively eliminating inter‐primitive unit cell π‐bonding interactions, and ii) non‐crystalline Zr/Hf Si oxynitrides without nanocrystalline grain boundaries.

/pdf/spectroscopic-studies-of-electronically-active-defects-in-5134llxktz.pdf

Gerald Lucovsky

Papers

Controlled chemical phase separation in binary and ternary composites: A pathway to isotropic optical and electrical behavior for device applications

Diffusion of hydrogen and deuterium in stack systems of SixNyHz/ SixNyDz and crystalline Si

The Effects of Interfacial Suboxide Transition Regions on Direct Tunneling in Oxide and Stacked Oxide-Nitride Gate Dielectrics

Local Bonding Arrangements in Amorphous Ge2Sb2Te5: The Importance of GE and TE Bonding

Spectroscopic Studies of Electronically Active Defects in Transition Metal Oxides for Advanced Si Devices