Compact binary coalescing systems: binary neutron stars, neutron star black hole pairs and binary black hole systems, represent promising candidates for gravitational wave first detection and have the potential to provide precise tests of the strong-field predictions of general relativity. Observations of binary black hole (BBH) systems will provide a wealth of information relevant to fundamental physics, astrophysics and cosmology. The search for such systems is a major priority of the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations. A major area of research within LIGO-Virgo analysis groups is incorporation of spin into the search template banks used for binary black hole systems. In this dissertation, I compare the injection efficiency and parameter recovery from three binary black hole searches. One of the searches presented here uses non-spinning templates and represents the standard LIGO search for binary black holes with total masses between 35 and 100M[circle with dot]. The other two use spin aligned and anti-aligned templates representing a future search for black hole binary systems with total masses between 35-100M[circle with dot]. One of the two spinning searches has the spin parameter set to zero, nonspinning, as a check of the spinning method. (Additionally the (anti-)aligned spin searches use a retooling of the standard pipeline taking advantage of a code base designed specifically to handle Advanced LIGO data.) All three searches were run on artificial data created by the Numerical Injection Analysis 2 collaboration (NINJA2) containing Gaussian noise and numerically generated signals modeling aligned and anti-aligned spinning binary black holes. I found that for the analyzed two weeks of data the three searches recover injections with nearly equal efficiency; however, the spinning search recovers the parameters of the injections more accurately than the non-spinning search. Specifically, the parameter recovery of the spins shows a correlation between the injected and recovered spins, and the addition of spin to the template bank improves the recovery of the signal-to-noise ratio and the chirp mass for an injected signal. While spin aligned situations are geometrically low probability configurations, there are plausible astrophysical effects that lead to alignment of spins prior to merger. Therefore my results show that the spin-aligned template bank search represents an improvement on the standard non-spinning search in the highmass region and should be pursued on real data. / text

Widespread use of organic light emitting diodes (OLEDs) in solid state lighting and display technologies require efficiency and lifetime improvements, as well as cost reductions, inclusive of the transparent conducting oxide (TCO). Indium tin oxide (ITO) is the standard TCO anode in OLEDs, but indium is expensive and the Earth's reserve of this element is limited. Zinc oxide (ZnO) and its variants such as aluminum-doped ZnO (AZO) exhibit comparable electrical conductivity and transmissivity to ITO, and are of interest for TCO applications. However, the workfunction of ZnO and AZO is smaller compared to ITO. The smaller workfunction of AZO results in a higher hole injection barrier at the anode/organic interface, and methods of tuning its workfunction are required. This dissertation tested the hypothesis that workfunction tuning of AZO films could be achieved by surface modification with electronegative oxygen and fluorine plasmas, or, via use of nanoscale transition metal oxide layers (MoOx, VOx and WOx). Extensive UPS, XPS and optical spectroscopy studies indicate that O2 and CFx plasma treatment results in an electronegative surface, surface charge redistribution, and a surface dipole moment which reinforces the original surface dipole leading to workfunction increases. Donor-like gap states associated with partially occupied d-bands due to non-stoichiometry determine the effective increased workfunction of the AZO/transition-metal oxide stacks. Reduced hole injection barriers were engineered by ensuring that the surface ad-layers were sufficiently thin to facilitate Fowler-Nordheim tunneling. Improved band alignments resulted in improved hole injection from the surface modified AZO anodes, as demonstrated by I-V characterization of hole only structures. Energy band alignments are proposed based on the aforementioned spectroscopies. Simple bilayer OLEDs employing the surface modified AZO anodes were fabricated and characterized to compare their performance with standard ITO. Anodes consisting of AZO with MoOx or VOx interfacial layers exhibited 50% and 71% improvement in power efficiency (PE) and external quantum efficiency (EQE), respectively, compared to ITO at a working voltage of 9 V. The efficiencies of dipole reinforced AZO (O2/CFx plasma treated) anodes were comparable to ITO. The improved performance of the surface modified AZO anodes compared to as-deposited AZO is ascribed to improved hole injection, improved charge balance, and improved radiative recombination kinetics. The results suggest that surface modified AZO anodes are a promising alternative to ITO, given the lower cost and Earth abundance of Al and Zn.

Les dispositifs spintroniques exploitent le degré de liberté du spin électronique pour traiter l'information. Dans cette thèse, nous étudions les propriétés de transport quantique dépendant du spin pour optimiser les performances des composants associés. Par l’approche ab initio, nous calculons la magnétorésistance à effet tunnel (tunneling magnetoresistance, TMR), l’effet Hall de spin (spin Hall effect, SHE) et l’efficacité de l’injection de spin (spin injection efficiency, SIE). Nous montrons ainsi que les métaux lourds (heavy metals, HM) influencent la TMR dans des jonctions tunnel magnétiques (magnetic tunnel junctions, MTJs) à base de MgO. L’utilisation de W, Mo, ou Ir peut améliorer la TMR. De plus, le dopage par substitution aide à optimiser le SHE dans les HMs, ce qui renforce les angles de Hall de spin (SHA) pour rendre plus efficace le renversement d’aimantation par couple spin-orbite (spin-orbit torque, SOT) dans les MTJ. Afin de contourner les problèmes induits par le désaccord de maille entre couches ferromagnétiques et MgO, nous avons conçu une MTJ basée sur l'hétérojonction VSe₂/MoS₂ de van der Waals (vdW) et calculons la TMR à température ambiante. L’apparition d’effets de résonance tunnel permet d’utiliser la tension appliquée pour moduler la TMR dans cette structure. Nous proposons également d’y favoriser le SOT en utilisant des matériaux 2D avec un fort SHE. MoTe₂ et WTe₂ apparaissent comme de bons candidats. Ces dichalcogénures de métaux de transition (transition metal dichalcogenides, TMDC) présentent un fort SHE ainsi que de grands SHA grâce à leur faible conductivité électrique. Enfin, motivés par la demande d'un dispositif commutable bidimensionnel à grande longueur de diffusion spin, nous étudions un système d'injection de spin dans le silicène et obtenons des SIE élevés sous tension appliquée. L’ensemble de ces travaux apportent un éclairage pour la recherche de nouveaux dispositifs spintroniques. / Spintronics devices manipulate the electron spin degree of freedom to process information. In this thesis, we investigate spin-dependent quantum transport properties to optimize the performances of spintronics devices. Through ab initio approach, we research the tunneling magnetoresistance (TMR), spin Hall effect (SHE), as well as spin injection efficiency (SIE). It has been demonstrated that heavy metals (HMs) are able to modulate TMR effects in MgO-based magnetic tunnel junctions (MTJs), and tungsten, molybdenum, and iridium are promising to enhance TMR. Moreover, substitutional atom doping can effectively optimize SHE of HMs, which would strengthen spin Hall angles (SHAs) to achieve efficient spin-orbit torque (SOT) switching of MTJs. To eliminate the mismatch between ferromagnetic and barrier layers in MgO-based MTJs, we design the MTJ with bond-free van der Waals (vdW) heterojunction VSe₂/MoS₂ and report the room-temperature TMR. The occurrence of quantum-well resonances enables voltage control to be an effective method to modulate TMR ratios in vdW MTJ. We put forward the idea of SOT vdW MTJ, which employs SOT to switch vdW MTJ and requires vdW materials with strong SHE. Research on MoTe₂ and WTe₂ verifies the possibility of realizing this idea. Both of them are layered transition metal dichalcogenides (TMDC) and exhibit strong SHEs, as well as large SHAs thanks to their low electrical conductivity. Lastly, motivated by the demand of a two-dimensional (2D) switchable device with long spin diffusion length, we construct the spin injection system with silicene monolayer, and reveal high SIEs under electric fields. Works in this thesis would advance the research of spintronics devices.