Photoelectronic effects in Cadium Selenide

Donor and acceptor type defect and Impurity centres in CdSe single crystals have been Investigated using photoconductivity and space-charge capacitance techniques, such as photocapacltance (PHCAF), Infrared quenching of PHCAP, PHCAP transients, deep level transient spectroscopy (DLTS) and optical DLTS. Highly resistive ( ρ> 10(^6) ῼ cm) photoconductive samples and medium resistivity (1 - 1000) n cm material for Schottky barrier formation have been prepared from the very conducting ( ~ 10(^-2) ῼ cm) as-grown crystals, either by annealing in selenium vapour or by copper doping. Samples annealed in selenium vapour had an acceptor level 0.62-0.64eV above the valence band, with a hole capture cross-section of 1010(^-14) cm(^2) which indicated that it is the main sensitising centre for photoconductivity in CdSe. There was also a well defined donor level ~ 0.12eV below the conduction band and an acceptor level ~0.22eV above the valence band. Similar measurements on CdSe crystals intentionally doped with copper revealed that the copper centre lies ~l.0eV above the valence band and has capture cross-sections of ~4.10(-12) cm(^2) and 7.10(^-18)cm(^2) for holes and electrons respectively, clearly demonstrating that copper behaves as a sensitising centre in CdSe, as it does in most of the II-VI compounds. Oxygen played an important role in controlling the electrical characteristics of the Schottky devices associated with the conversion of the surface structure of CdSe from a hexagonal to cubic phase. This phenomenon can be reproduced by mechanically polishing a hexagonal crystal. The cubic surface layers produced in this way have much higher resistivities than the underlying hexagonal base material and they give rise to photoconductlve effects. Measurements on such surfaces revealed an additional acceptor level ~ 0.38eV above the valence band. The barrier height of the CdSe-Au Schottky contact has proved to be dependent on the work function of the metal, the thickness and nature of Interfacial layers, and the amount of charge stored in the Interface states

Searching to Translate and Translating to Search: When Information Retrieval Meets Machine Translation

With the adoption of web services in daily life, people have access to tremendous amounts of information, beyond any human's reading and comprehension capabilities. As a result, search technologies have become a fundamental tool for accessing information. Furthermore, the web contains information in multiple languages, introducing another barrier between people and information. Therefore, search technologies need to handle content written in multiple languages, which requires techniques to account for the linguistic differences. Information Retrieval (IR) is the study of search techniques, in which the task is to find material relevant to a given information need. Cross-Language Information Retrieval (CLIR) is a special case of IR when the search takes place in a multi-lingual collection. Of course, it is not helpful to retrieve content in languages the user cannot understand. Machine Translation (MT) studies the translation of text from one language into another efficiently (within a reasonable amount of time) and effectively (fluent and retaining the original meaning), which helps people understand what is being written, regardless of the source language. Putting these together, we observe that search and translation technologies are part of an important user application, calling for a better integration of search (IR) and translation (MT), since these two technologies need to work together to produce high-quality output. In this dissertation, the main goal is to build better connections between IR and MT, for which we present solutions to two problems: Searching to translate explores approximate search techniques for extracting bilingual data from multilingual Wikipedia collections to train better translation models. Translating to search explores the integration of a modern statistical MT system into the cross-language search processes. In both cases, our best-performing approach yielded improvements over strong baselines for a variety of language pairs. Finally, we propose a general architecture, in which various components of IR and MT systems can be connected together into a feedback loop, with potential improvements to both search and translation tasks. We hope that the ideas presented in this dissertation will spur more interest in the integration of search and translation technologies

Automated build service to facilitate Continuous Delivery

Continuous delivery can be seen as an evolution from agile software development methods and high demands to deliver working software quickly. It aims to always be able to deliver working and reliable software in short iterations by continuously integrate, build and test the software. This puts high demands on automation and the focus of this thesis is to automate the pipeline between source code and deployable software artifacts. The problem definition of this thesis is to improve and unify the deployment pipeline of software running on Linux at IKEA IT. The project resulted in a service that supports continuous delivery by providing automated building, testing, signing and deployment of software. It runs in production environment at IKEA IT and provides a high level of automation. It was evaluated with help from end users and the eval- uation showed that the service is useful for the intended users and automate several steps they earlier have had to do manually