Photoluminescence studies of CdTe films and junctions

Device quality CdTe films and junctions have been studied using low-temperature photoluminescence (PL) measurements. The behavior of the PL was studied as a function of the measurement temperature and excitation intensity. The CdTe films and junctions were prepared under various deposition conditions to determine the effect of film deposition and solar cell fabrication parameters, such as the effect of oxygen, and chloride treatment. A PL band located at 1.232 eV has been attributed to the presence of oxygen. This band is present only in as-deposited samples excited at the CdTe surface. Samples annealed in the presence of CdCl₂ exhibit a single PL band located at 1.42 eV. A model explaining the behavior of these bands is presented.     

Visual Impairments and Mobile Touchscreen Interaction: State-of-the-Art,Causes of Visual Impairment,and Design Guidelines

ABSTRACT

This article identifies, catalogues, and discusses factors that are responsible for causing visual impairment of either a pathological or situational nature for touch and gesture input on smart mobile devices. Because the vast majority of interactions with touchscreen devices are highly visual in nature, any factor that prevents a clear, direct view of the mobile device’s screen can have potential negative implications on the effectiveness and efficiency of the interaction. This work presents the first overview of such factors, which are grouped in a catalogue of users, devices, and environments. The elements of the catalogue (e.g., psychological factors that relate to the user, or the social acceptability of mobile device use in public that relates to the social environment) are discussed in the context of current eye pathology classification from medicine and the recent literature in human–computer interaction on mobile touch and gesture input for people with visual impairments, for which a state-of-the-art survey is conducted. The goal of this work is to help systematize research on visual impairments and mobile touchscreen interaction by providing a catalogue-based view of the main causes of visual impairments affecting touch and gesture input on smart mobile devices.     

Point &; click mediated interactions for large home entertainment displays

This work introduces and discusses the implementation details of a novel concept for a home entertainment system together with an affordable controlling interface that uses point & click interactions in order to create, mix and manipulate media screens within the same projection-based display. Scenarios for single and multiple viewers are discussed with users being able to create, reposition, resize, and control their own-defined media screens. The standard and familiar WIMP interaction techniques are transferred from PCs to home entertainment using a motion-sensing remote controller. An optional system feature is described for the automatic configuration of such media screens by analyzing the home environment using computer vision techniques. Observations from initial user studies are reported with regards to the perceived usefulness and acceptability of the proposed system. The main benefit introduced by this work is that of a large entertainment display that becomes shared and personalized while it is being adapted and fit into the home environment.     

Photoluminesence studies of CdTe/SnO2 and CdTe/CdS heterojunctions: The influence of oxygen and the CdCl2 heat treatment

The influence of oxygen and annealing in the presence of CdCl₂ on the photoluminescence (PL) spectra of CdTe, component of SnO₂/CdTe heterojunction (HJ), has been studied in a temperature range of 17-100 K. The changes in the photoluminescence spectra were studied as a function of excitation intensity. Analysis of the PL spectra was carried out with considerations of spectra obtained from CdS/CdTe heterojunctions. CdTe side PL (SnO₂/CdTe HJ) consisted of 1.450 eV-DA defect band and 1.243 eV band (17 K). Annealing resulted in the disappearance of 1.243 eV band in oxygen containing samples. Interface PL for the unannealed samples consisted of mainly the 1.264 eV and a trace of the defect band. The CdCl₂ treatment is responsible for an almost symmetrical 1.416 eV band.     

The copper influence on the PL spectra of CdTe thin film as a component of the CdS/CdTe heterojunction

The influence of annealing in the presence of CdCl₂ and a thin copper layer deposited onto CdTe on the photoluminescence spectra of CdTe, as a component of CdS/CdTe heterojunction, has been studied for two excitation wavelengths: 0.337 μm and 0.6328 μm. The behavior of the PL was studied as a function of the measurement temperature and excitation intensity. At 0.6328 μm excitation, the interface PL consists of a known 1.43X band, and the chloride annealing enhances radiative transitions at 1.536 eV. The intensity of the 1.536 eV transitions increases when Cu is present. The PL of as-deposited CdTe films prepared in the presence of oxygen has the 1.45X band attenuated when excited with 0.337 μm excitation wavelength.     

Semantic ambient media: From ambient advertising to ambient-assisted living

The term ambient media was in its beginning used only for ambient advertising. Nowadays it denotes the media environment and the communication of information in ubiquitous and pervasive environments. With the addition of intelligence, the new field of semantic ambient media was established. In recent years, the field of semantic ambient media has spread its span from only a few sub-areas, such as ambient advertising, to new ones, such as ambient-assisted living (AAL) and health-monitoring media, significantly supported by intelligence. The study presented in this paper provides an advanced introduction to the field of semantic ambient media including the solutions for threat issues and illustration of success stories of the field. It conducts a survey of the related work and presents a thorough discussion of it. The related work is grouped according to the coverage of the principles of semantic ambient media. Based on the state-of-the-art research, the future possibilities of the field are demonstrated, especially for the ambient-assisted living, audio-visual rendering of media objects, user design principles and the society impact of the field. The paper provides ideas for impacting ambient media and directions and questions for further research. It also discusses the potential of the combination of several research studies.     

Presence bubbles: supporting and enhancing human-human interaction with ambient media

People communicate using speech, gestures and emotions but sometimes these may not be enough in order to express the true intended message. This results in miscommunication and sometimes frustration which are perceived negatively by the interacting participants. We propose an investigation into expressive ambient media in the form of visual surfaces as digital enhancements for Human-Human Interaction. The goal is to allow new modalities for self-expression as well as to enhance communication by displaying personal digital content in the form of Presence Bubbles. Ambient media allow thus communication, presence and socialization opportunities and transform into responsive and expressive media for supporting and enhancing human-human interaction.     

Personalized gesture interactions for cyber-physical smart-home environments

A gesture-based interaction system for smart homes is a part of a complex cyber-physical environment, for which researchers and developers need to address major challenges in providing personalized gesture interactions. However, current research efforts have not tackled the problem of personalized gesture recognition that often involves user identification. To address this problem, we propose in this work a new event-driven service-oriented framework called gesture services for cyber-physical environments (GS-CPE) that extends the architecture of our previous work gesture profile for web services (GPWS). To provide user identification functionality, GS-CPE introduces a two-phase cascading gesture password recognition algorithm for gesture-based user identification using a two-phase cascading classifier with the hidden Markov model and the Golden Section Search, which achieves an accuracy rate of 96.2% with a small training dataset. To support personalized gesture interaction, an enhanced version of the Dynamic Time Warping algorithm with multiple gestural input sources and dynamic template adaptation support is implemented. Our experimental results demonstrate the performance of the algorithm can achieve an average accuracy rate of 98.5% in practical scenarios. Comparison results reveal that GS-CPE has faster response time and higher accuracy rate than other gesture interaction systems designed for smart-home environments.