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

Chemical Bonding Self-Organizations and Percolation Theory Applied to Minimization of Macroscopic Strain: Internal Interfaces in Non-Crystalline and Nano-Crystalline Thin Films

The primary driving force for the introduction of alternative gate dielectrics in advanced complementary metal oxide semiconductor (CMOS) devices is the dramatic increase in direct tunneling that occurs when the SiO2 physical thickness is reduced to less than 3 nm. For example the direct tunneling current at an oxide bias of 1 V is approximately 10−2 A/cm2 for an oxide physical thickness of 2.0 nm, and increases approximately one order of magnitude for each additional decrease of 0.2 nm thereby placing significant limitations on the performance and reliability of CMOS field effect transistor (FET) devices and integrated circuits (ICs). If the limitations for direct tunneling leakage current are taken to be 1–5 A/cm2 for high performance devices, and <10−2 A/cm2 for mobile and low power devices, tunneling leakage limits SiO2 physical thickness reductions to ∼1–4 to 1.6 nm, and ∼2.0 nm, respectively. Since there is a linear scaling relationship between lateral in-plane device dimensions, and SiO2 physical and equivalent oxide thickness (EOT), these tunneling limitations have important implications for the ultimate decreases in device dimensions, and increases in device integration (1). One obvious solution is to replace SiO2 by alternative gate dielectrics that have higher dielectric constants, k, than the nominal value of ko = 3.9 ± 0.1 for SiO2, thereby increasing the physical thickness of the dielectric by the ratio of dielectric constants, k/ko, without reducing the gate dielectric capacitance, Cox. However, the very large decreases in tunneling currents anticipated by increases in physical thickness alone can be significantly mitigated by decreases in (i) the

Electronic structure and chemical bonding in high-k transition metal and lanthanide series rare earth alternative gate dielectrics: applications to direct tunneling and defects at dielectric interfaces

X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-k transition metal (TM) and trivalent lanthanide rare earth (RE) oxide dielectrics. The lowest conduction band d*-states in nano-crystalline TiO2, ZrO2 and HfO2 are correlated with features in the O K1 edge, and transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. Optical band gaps, Eopt, and conduction band offset energy with respect to Si, EB, scale monotonically with d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L2,3 spectrum of TiO2, and the O K1 derivative spectra for ZrO2 and HfO2 indicate a complete removal of d-state degeneracies resulting from a static Jahn-Teller effect. Similar degeneracy removals are shown for complex nano-crystalline TM/RE oxides such as Zr and Hf titanates, and La, Gd and Dy scandates. XAS and band edge spectra indicate an additional band edge defect state assigned Jahn-Teller distortions...

PART II: CONDUCTION BAND-EDGE STATES ASSOCIATED WITH REMOVAL OF d-STATE DEGENERACIES BY THE STATIC JAHN-TELLER EFFECT

Concentrations of electrically active defects in a-Si are three orders of magnitude lower than the density of dangling bonds on internal void surfaces as estimated from the density deficiency of a-Si with respect to crystalline, c-Si. This reduced defect concentration is explained by a chemically controlled self-organization, in which formation of divacancies reduces Si-atom bond-bending constraints on the terminal atoms of the divacancy, as well as their immediate neighbours. This broken constraint relaxation process prevents percolation of local rigidity, thereby explaining defect state reductions. It also identifies an optimized bonded-H concentration in a-Si:H that is enabling for device applications such as solar cells and thin film transistors which require doping.

Gerald Lucovsky

Papers

Chemical Bonding Self-Organizations and Percolation Theory Applied to Minimization of Macroscopic Strain: Internal Interfaces in Non-Crystalline and Nano-Crystalline Thin Films

Electronic structure and chemical bonding in high-k transition metal and lanthanide series rare earth alternative gate dielectrics: applications to direct tunneling and defects at dielectric interfaces

PART II: CONDUCTION BAND-EDGE STATES ASSOCIATED WITH REMOVAL OF d-STATE DEGENERACIES BY THE STATIC JAHN-TELLER EFFECT

A self-consistent model for defect states in a-Si and a-Si:H

Fixed charge and interface traps at heterovalent interfaces between Si(100) and non-crystalline Al2O3–Ta2O5 alloys