Thermodynamics of zinc insertion in CuGaS2:Ti, used as a modulator agent in an intermediate-band photovoltaic material

An intermediate-bandphotovoltaicmaterial, which has an isolated metallic band located between the top of the valence band and bottom of the conduction band of some semiconductors, has been proposed as third generation solar cell to be used in photovoltaic applications. Density functional theory calculations of Zn in CuGaS2:Ti have previously shown that, the intermediate-band position can be modulated in proportion of Zn insertion in such a way that increasing Zn concentration can lead to aband-gap reduction, and an adjustment of the intermediate-band position. This could be interesting in the formation of an intermediate-bandmaterial, that has the maximum efficiency theoretically predicted for the intermediate-band solar cell. In this work, the energetics of several reaction schemes that could lead to the decomposition of the modulated intermediate-bandphotovoltaicmaterial, CuGaS2:Ti:Zn, is studied in order to assess the thermodynamic stability of this material. Calculations of the total free energy and disorder entropy have been taken into account, to get the reaction energy and free energy of the compound decomposition, which is found to be thermodynamically favorable

Understanding the selective area growth of GaN nanocolumns by MBE using Ti nanomasks

The influence of the substrate temperature, III/V flux ratio, and mask geometry on the selective area growth of GaN nanocolumns is investigated. For a given set of growth conditions, the mask design (diameter and pitch of the nanoholes) is found to be crucial to achieve selective growth within the nanoholes. The local III/V flux ratio within these nanoholes is a key factor that can be tuned, either by modifying the growth conditions or the mask geometry. On the other hand, some specific growth conditions may lead to selective growth but not be suitable for subsequent vertical growth. With optimized conditions, ordered GaN nanocolumns can be grown with a wide variety of diameters. In this work, ordered GaN nanocolumns with diameter as small as 50 nm are shown.

Understanding the Selective Area Nucleation and Growth of GaN nanocolumns by MBE using Ti nanomasks

•Self- assembled Ga(In)N Nanorods and Nanostructures •Ordered growth of GaN Nanorods: masks issues •Ordered growth of GaN Nanorods: mechanisms •White NanoLEDs

Opus sermonum de aduentu / religiosissimi viri, artiu[m] ac sacre theologie in Parisien[si] academia quondam professoris, et euangelice doctrine co[n]cionatoris celebratissimi Ioannis Raulini ordinis Cluniacen[sis], dilige[n]ti quidem cura mendis o[mn]ibu

Raulin, Jean (O.S.B.), 1443-1514. Itinerarium paradisi religiosissimi patris artium ac sacre pagine p[ro]fessoris Parisien[sis] diuiniq[ue] verbi declamatoris facundissimi magistri Ioannis Raulin ordinis Cluniace[nsis], co[m]plecte[n]s sermones de Penit

Opus sermonum de aduentu / religiosissimi viri, artiu[m] ac sacre theologie in Parisien[si] academia quondam professoris, et euangelice doctrine co[n]cionatoris celebratissimi Ioannis Raulini ordinis Cluniacen[sis], dilige[n]ti quidem cura mendis o[mn]ibu

Pie de imp. tomado del colofón

Sub-bandgap spectral photo-response analysis of Ti supersaturated Si

We have analyzed the increase of the sheet conductance (ΔG□) under spectral illumination in high dose Ti implanted Si samples subsequently processed by pulsed-laser melting. Samples with Ti concentration clearly above the insulator-metal transition limit show a remarkably high ΔG□, even higher than that measured in a silicon reference sample. This increase in the ΔG□ magnitude is contrary to the classic understanding of recombination centers action and supports the lifetime recovery predicted for concentrations of deep levels above the insulator-metal transition.

Interstitial Ti for intermediate band formation in Ti-supersaturated silicon

We have analyzed by means of Rutherford backscattering spectrometry (RBS) the Ti lattice location and the degree of crystalline lattice recovery in heavily Ti implanted silicon layers subsequently pulsed laser melted (PLM). Theoretical studies have predicted that Ti should occupy interstitial sites in silicon for a metallic-intermediate band (IB) formation. The analysis of Ti lattice location after PLM processes is a crucial point to evaluate the IB formation that can be clarifyied by means of RBS measurements. After PLM, time-of-flight secondary ion mass spectrometry measurements show that the Ti concentration in the layers is well above the theoretical limit for IB formation. RBS measurements have shown a significant improvement of the lattice quality at the highest PLM energy density studied. The RBS channeling spectra reveals clearly that after PLM processes Ti impurities are mostly occupying interstitial lattice sites.

Summa summarum que siluestrina dicitur nuperrime magna cum diligentia recognita ... huius quoq[ue] sum[m]e tabula in p[ar]tes duas diuisa est, sicut [et] ipsa su[m]ma, vt cuiq[ue] p[ar]ti sua p[ar]s r[espo]ndeat ...

Pie de imp. tomado del colofón de la segunda parte en 2Z5

Summa Caietana de peccatis ; et Noui Testame[n]ti ientacula / reuerendissimi domini Thome de Vio cardinalis sa[n]cti Xisti ; [per ... Ioannem Danielis ... accuratis reuisa].

Editor literario tomado del colofón

Effect of the temperature, strain rate and microstructure on flow and fracture characteristics of Ti-45Al-2Nb-2Mn+0.8vol.% TiB2 XD alloy

A series of quasi-static and dynamic tensile tests at varying temperatures were carried out to determine the mechanical behaviour of Ti-45Al-2Nb-2Mn+0.8vol.% TiB2 XD as-HIPed alloy. The temperature for the tests ranged from room temperature to 850  ∘C. The effect of the temperature on the ultimate tensile strength, as expected, was almost negligible within the selected temperature range. Nevertheless, the plastic flow suffered some softening because of the temperature. This alloy presents a relatively low ductility; thus, a low tensile strain to failure. The dynamic tests were performed in a Split Hopkinson Tension Bar, showing an increase of the ultimate tensile strength due to the strain rate hardening effect. Johnson-Cook constitutive relation was used to model the plastic flow. A post-testing microstructural of the specimens revealed an inhomogeneous structure, consisting of lamellar α2 + γ structure and γ phase equiaxed grains in the centre, and a fully lamellar structure on the rest. The assessment of the duplex-fully lamellar area ratio showed a clear relationship between the microstructure and the fracture behaviour.

Retos de la Gerencia de TI para construir sistemas de información exitosos: aportes claves del usuario final

Por décadas y hasta el presente, numerosos continúan siendo los casos de SI fallidos, parcial o totalmente, causando grandes pérdidas en las organizaciones y planteando serios retos a los profesionales de las TI y a los niveles de Dirección. La literatura reconoce que los principales factores influyentes son más de orden social que tecnológico, dando un peso relevante al rol de usuario final y sugiriendo profundizar en su investigación, por considerarlo como el “stakeholder” clave para el éxito de un SI. Este estudio empírico ha buscado ampliar las subdimensiones y analizar el impacto de tres factores críticos de dicho rol desde la perspectiva del mismo usuario final, no hallados en la literatura sobre el tema. Se presentan los resultados de un análisis cuantitativo y otro cualitativo, complementándose ambos enfoques y dando las mayores cargas a los factores “conocimientos” y “participación” efectiva. Las conclusiones más significativas resaltan la relevancia de la gerencia del conocimiento así como medidas preventivas respecto a las subdimensiones analizadas para reducir los riesgos inherentes. Se estima que los resultad os aportan mayor detalle a la teoría y a la práctica sobre los SI en las organizaciones.

Piezoelectric and electroacoustic properties of Ti-doped AlN thin films as a function of Ti content

In this work we present the assessment of the structural and piezoelectric properties of Al(0.5-x)TixN0.5 compounds (titanium content menor que6% atomic), which are expected to possess improved properties than conventional AlN films, such as larger piezoelectric activity, thermal stability of frequency and temperature resistance. Al:Ti:N films were deposited from a twin concentric target of Al and Ti by reactive AC sputtering, which provided films with a radial gradient of the Ti concentration. The properties of the films were investigated as a function of their composition, which was measured by electron dispersive energy dispersive X-ray spectroscopy and Rutherford backscattering spectrometry. The microstructure and morphology of the films were assessed by X-ray diffraction and infrared reflectance. Their electroacoustic properties and dielectric constant were derived from the frequency response of BAW test resonators. Al:Ti:N films properties appear to be strongly dependent on the Ti content, which modifies the AlN wurtzite crystal structure leading to greater dielectric constant, lower sound velocities, lower electromechanical factor and moderately improved temperature coefficient of the resonant frequency.

Estructuras, Procesos, Indicadores para Gestionar el Proceso de la Demanda Estratégica en las TI

En los últimos años, el desarrollo industrial a nivel globalizado en los diferentes sectores, la difusión de la TI y el uso estratégico de la misma, han crecido de manera exponencial. El uso adecuado de esta, se ha convertido en una gran preocupación para los órganos de gobierno de las organizaciones ya que la falta de dirección y control en las inversiones que se realizan en ellas, así como un uso inadecuado de las mismas pueden comprometer la consecución de los objetivos de la organización, su competitividad y su sostenibilidad a medio-largo plazo. La preocupación de los propietarios de los negocios es mejorar su rendimiento con la ayuda de la TI frente a sus competidores, realizando los procesos de negocio de una manera eficaz y eficiente, por lo que muchas organizaciones han realizado inversiones importantes en la adquisición de tecnología para lograr sus propósitos. Sin embargo la ejecución de estas inversiones no se ha gestionado adecuadamente, conforme a las políticas y planes especificados en los planes de negocio de la organización y la entrega de los servicios de TI no ha sido conforme a los objetivos previstos, generando pérdidas importantes y lo que es peor un gran deterioro de la imagen de la organización, por lo que consideramos a la gestión de la demanda estratégica de la TI como uno de los factores claves para el éxito de los negocios, el cual no ha sido tomada en cuenta por los consejos de gobierno o los altos ejecutivos de las organizaciones. La investigación comienza con una amplia revisión de la literatura, identificando dos elementos muy importantes, la demanda y el suministro de la TI dentro de la gobernanza corporativa de la TI; notándose la escasa información relacionado con la gestión de la demanda estratégica de la TI. Se realizó un estudio exploratorio para conocer como los miembros del consejo de administración y altos ejecutivos de una organización gestionan la demanda estratégica de la TI, obteniendo una respuesta de 130 encuestados, donde se confirma que hace falta normas o metodologías para la gestión de la demanda estratégica de la TI. En base a estos resultados se ha construido un marco de trabajo para todo el proceso de la gestión de la demanda de la TI y como una solución que se plantea en esta tesis doctoral, consiste en la elaboración de una metodología, combinando e integrando marcos de trabajo y estándares relacionados con la gobernanza corporativa de la TI. La metodología propuesta está conformada por tres fases, cada fase con sus actividades principales, y cada actividad principal por un conjunto de sub-actividades. Además, se establecen los roles y responsabilidades de los altos ejecutivos para cada una de las actividades principales. Esta propuesta debe ser de fácil implantación y aplicable en las organizaciones, permitiendo a estas afrontar con éxito el desarrollo de sus negocios, con una mejor calidad, reduciendo los costes de operación y empleando el menor tiempo posible. La validación de la metodología propuesta se realizó a través de una encuesta online y un estudio de casos. En la encuesta de validación participaron 42 altos ejecutivos de diferentes empresas y el estudio de casos se realizó con 5 empresas internacionales. Las respuestas de los estudios fueron analizados, para determinar la aceptación o el rechazo de la metodología propuesta por los participantes, confirmando la validez y confiabilidad del estudio. Este es uno de los primeros estudios reportado con evidencias empíricas para el proceso de la gestión de la demanda estratégica de la TI. Los resultados de esta investigación han sido publicados en revistas y congresos internacionales. ABSTRACT In recent years, the globalized industrial development, diffusion and strategic use of IT in different sectors has grown exponentially. Proper use of IT has become a major concern for government bodies and organizations. Uncontrolled or mismanaged IT investments or improper IT use may compromise the achievement of an organization’s objectives, competitiveness and sustainability in the medium to long term. Business owners set out to use IT to outperform their competitors, enacting business processes effectively and efficiently. Many organizations have made significant investments in technology in order to achieve their aims. However, the deployment of these investments has not been managed properly in accordance with the policies and plans specified in the organizations’ business plans, and IT services have not been delivered in accordance with the specified objectives. This has generated significant losses and, worse still, has seriously damaged the image of organizations. Accordingly, we believe that IT strategic demand management is one of the key factors for business success which has not been overlooked by the boards of trustees or senior executives of organizations. The research begins with an extensive review of the literature. This review has identified two very important elements: IT demand and supply within the corporate governance of IT. We have found that information related to IT strategic demand management is scant. We conducted an exploratory study to learn how members of the board of directors and senior executives of an organization manage IT strategic demand. The survey, which was taken by 130 respondents, confirmed that standards or methodologies are needed to manage IT strategic demand. Based on the results, we have built a framework for the entire IT demand management process. The solution proposed in this thesis is to develop a methodology, combining and integrating frameworks and standards related to the corporate governance of IT. The proposed methodology is divided into three phases. Each phase is composed of a series of key activities, and each key activity is further split into minor activities. We also establish the roles and responsibilities of senior executives for each of the key activities. This proposal should be easy to implement and apply in organizations, enabling corporations to successfully conduct better quality business, reduce operating costs and save time. The proposed methodology was validated by means of an online survey and a case study. The validation survey was completed by 42 senior executives from different companies, and the case study was conducted at five international companies. The study results were analysed to determine the acceptance or rejection of the proposed methodology by the participants, confirming the validity and reliability of the study. This is one the first studies to report empirical evidence for the process of IT strategic demand management. The results of this research have been published in international journals and conferences.

Electrical decoupling effect on intermediate band Ti-implanted silicon layers

We investigated the electrical transport properties of ultraheavily Ti-implanted silicon layers subsequently pulsed laser melted (PLM). After PLM, the samples exhibit anomalous electrical behaviour in sheet resistance and Hall mobility measurements, which is associated with the formation of an intermediate band (IB) in the implanted layer. An analytical model that assumes IB formation and a current limitation effect between the implanted layer and the substrate was developed to analyse this anomalous behaviour. This model also describes the behaviour of the function V/Delta V and the electrical function F that can be extracted from the electrical measurements in the bilayer. After chemical etching of the implanted layer, the anomalous electrical behaviour observed in sheet resistance and Hall mobility measurements vanishes, recovering the unimplanted Si behaviour, in agreement with the analytical model. The behaviour of V/Delta V and the electrical function F can also be successfully described in terms of the analytical model in the bilayer structure with the implanted layer entirely stripped.