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

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5×1012 to 1×1014/cm2 evolves into a distribution of {311} interstitial agglomerates during the initial annealing stages at 670–815 °C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the dissolution of {311} defects during Ostwald ripening with an activation energy of 3.8±0.2 eV. The excess interstitials drive substitutional B into electric...

/pdf/physical-mechanisms-of-transient-enhanced-dopant-diffusion-zkysm82pgr.pdf

Physical mechanisms of transient enhanced dopant diffusion in ion-implanted silicon

Black silicon (BSi) represents a very active research area in renewable energy materials. The rise of BSi as a focus of study for its fundamental properties and potentially lucrative practical applications is shown by several recent results ranging from solar cells and light-emitting devices to antibacterial coatings and gas-sensors. In this paper, the common BSi fabrication techniques are first reviewed, including electrochemical HF etching, stain etching, metal-assisted chemical etching, reactive ion etching, laser irradiation and the molten salt Fray-Farthing-Chen-Cambridge (FFC-Cambridge) process. The utilization of BSi as an anti-reflection coating in solar cells is then critically examined and appraised, based upon strategies towards higher efficiency renewable solar energy modules. Methods of incorporating BSi in advanced solar cell architectures and the production of ultra-thin and flexible BSi wafers are also surveyed. Particular attention is given to routes leading to passivated BSi surfaces, which are essential for improving the electrical properties of any devices incorporating BSi, with a special focus on atomic layer deposition of Al2O3. Finally, three potential research directions worth exploring for practical solar cell applications are highlighted, namely, encapsulation effects, the development of micro-nano dual-scale BSi, and the incorporation of BSi into thin solar cells. It is intended that this paper will serve as a useful introduction to this novel material and its properties, and provide a general overview of recent progress in research currently being undertaken for renewable energy applications.

/pdf/black-silicon-fabrication-methods-properties-and-solar-1gjw6owq4d.pdf

Black silicon: fabrication methods, properties and solar energy applications

Ion-beam-induced amorphization in Si has attracted significant interest since the beginning of the use of ion implantation for the fabrication of Si devices. A number of theoretical calculations and experiments were designed to provide a better understanding of the mechanisms behind the crystal-to-amorphous transition in Si. Nowadays, a renewed interest in the modeling of amorphization mechanisms at atomic level has arisen due to the use of preamorphizing implants and high dopant implantation doses for the fabrication of nanometric-scale Si devices. In this paper we will describe the most significant experimental observations related to the ion-beam-induced amorphization in Si and the models that have been developed to describe the process. Amorphous Si formation by ion implantation is the result of a critical balance between the damage generation and its annihilation. Implantation cascades generate different damage configurations going from isolated point defects and point defect clusters in essentially ...

https://www.ele.uva.es/~mmm/papers/2004_Pelaz_JAP_96.pdf

Ion-beam-induced amorphization and recrystallization in silicon

On annealing a boron implanted Si sample at similar to800 degreesC, boron in the tail of the implanted profile diffuses very fast, faster than the normal thermal diffusion by a factor 100 or more. ...

Transient enhanced diffusion of Boron in Si

Diffusion of B in Ge is studied in the temperature range 800–900°C using implantation doping and B doped epitaxial Ge layers. Concentration profiles before and after furnace annealing were obtained using high resolution secondary ion mass spectroscopy (SIMS). Diffusion coefficients were calculated by fitting the annealed profiles using TSUPREM. We obtained diffusivity values which are at least two orders of magnitude lower than the lowest values previously reported in the literature. Using our values an activation energy of 4.65(±0.3)eV is calculated. Present experimental results suggest that interstitial mediated mechanism should be considered for B diffusion in Ge in accordance with recent theoretical calculations. Annealed SIMS profiles also suggest that B solid solubility in Ge is ∼2×1018cm−3 at 875°C which agrees with literature values.

Diffusion of boron in germanium at 800–900°C

We investigate the thermal stability of boron-doped junctions formed by Ge preamorphization and solid phase epitaxial regrowth Isochronal annealing and characterization by sheet resistance, secondary-ion mass spectrometry, and spreading-resistance measurement are used to extract detailed information on the thermal stability of the boron activation Using a previously established model of self-interstitial defect evolution from clusters to dislocation loops, we perform simulations of the release of interstitials from the end-of-range region The simulations indicate that the measured deactivation is driven by interstitials emerging from the end-of-range defect region

Evidence on the mechanism of boron deactivation in Ge-preamorphized ultrashallow junctions

A study of the relative thermal stability of perfect and faulted dislocation loops formed during annealing of preamorphized silicon wafers has been carried out. A series of transmission electron microscopy experiments has been designed to study the influence of the ion dose, the annealing ambient and the proximity of a free surface on the evolution of both types of loops. Samples were implanted with either 150 keV Ge+ or 50 keV Si+ ions to a dose of 2×1015 cm−2 and annealed at 900 °C in N2, N2O, and O2. The calculations of formation energy of both types of dislocation loops show that, for defects of the same size, faulted dislocation loops (FDLs) are more energetically stable than perfect dislocation loops (PDLs) if their diameter is smaller than 80 nm and vice versa. The experimental results have been analyzed within the framework of the Ostwald ripening of two existing populations of interstitial defects. It is found that the defect ripening is nonconservative if the surface is close to the end of range...

Formation energies and relative stability of perfect and faulted dislocation loops in silicon

A physically motivated model that accounts for the spatial and temporal evolution of self-interstitial agglomerates in ion-implanted Si is presented. For the calibration of the model, a genetic algorithm is used to find the optimum set of physical parameters from experimental data. Mean-size evolution of {113} defects obtained by transmission electron microscopy and self-interstitial oversaturation results measured in the vicinity of extended defects are combined in the same fitting procedure. The calibration of parameters shows that binding energies of small self-interstitial clusters exhibit strong maxima, as reported in other investigations. Results of the calibrated model are compared to experimental data obtained in complementary investigations. It is demonstrated that the model is able to predict a wide variety of physical phenomena, from the oversaturation of self-interstitials via the mean-size evolution of {113} defects to the depth distribution of the density of the latter.

A physically based model for the spatial and temporal evolution of self-interstitial agglomerates in ion-implanted silicon

Transient diffusion of ion‐implanted B is inhibited in the presence of high C or B concentrations, due to the formation of interstitial clusters stabilized by impurity atoms. Comparison between experiments and simulations suggests that the number of self‐interstitials trapped per clustered impurity atoms is ≊1.15 for C and ∼1 for B, consistent with a volume compensation mechanism.

N. E. B. Cowern

Papers

Diffusion of boron in germanium at 800–900°C

Evidence on the mechanism of boron deactivation in Ge-preamorphized ultrashallow junctions

Formation energies and relative stability of perfect and faulted dislocation loops in silicon

A physically based model for the spatial and temporal evolution of self-interstitial agglomerates in ion-implanted silicon

Role of C and B clusters in transient diffusion of B in silicon