Dual Gate Black Phosphorous Photodetectors Using a Polymer Electrolyte for Integrated Photonics and Optoelectronics Applications

Les photodétecteurs occupent une place prépondérante dans un nombre important de dispositifs. Ceux-ci sont utilisés dans plusieurs pour les communications optiques, la détection d'images, la vision nocturne, l’inspection alimentaire, l’imagerie médicale, etc. La conception de détecteurs infrarouges requiert l’utilisation de matériaux autre que le silicium démontrant une haute efficacité, détectivité et un temps de réponse rapide. Ceux-ci sont typiquement couteux et difficiles à intégrés avec des substrats flexibles ou des circuits photoniques et optoélectroniques conventionnels. Dans cette thèse, nous présentons un photodétecteur à base de phosphore noir avec une architecture à double grille basé sur sur un électrolyte polymère solide pour des applications en photonique intégrée et en optoélectronique. La combinaison de la grille électrolytique et du photodétecteur BP conventionnel permet un contrôle efficace du transport électrique et de la modulation de la densité de porteurs dans le canal BP. Les détecteurs à double grille fabriqués avec cette approche améliorent le rapport ON / OFF de 50 fois par rapport à l’architecture conventionnelle. Ceux-ci présentent également du courant de drain avec la configuration de contact source-drain orthogonale. Finalement, l’électrolyte polymère protège les flocons de BP de l'oxydation de surface et présentent des caractéristiques électriques stables dans les conditions ambiantes. Nous obtenons une modulation du photocourant par un facteur de 4 pour des puissances incidentes variant de 0.5 mW à 5 mW. Dans cette gamme de puissance, une modulation du photocourant par un facteur de 2 est obtenu en variant la tension de grille supérieure (variée de 3V à -3V) à une longueur d'onde de 808 nm. À plus faible puissance, le photodétecteur donne une modulation de photocourant largement supérieure à l’architecture conventionnelle: environ 16 fois avec une tension de grille d'électrolyte ajustée de -2 V à 2 V par rapport au dispositif à grille inférieure qui est d'environ 2.5 fois avec une tension de grille variant de -10 V 10 V dans le proche infrarouge. Des sensibilités de centaines de mA / W sont obtenues pour les photodétecteurs BP dans les régimes visible et proche-infrarouge.----------Abstract Visible and infrared photodetectors have become important in a multitude of present-day devices that find emerging applications in several fields: optical communications, image sensing, night vision, food monitoring and medical imaging etc. However, photodetection beyond the visible region of spectrum requires investigating unconventional materials and designs that deliver superior performance in terms of photocurrent/responsivity, detectivity and response speed, that also allow ultra-low weight, low-cost, flexible and easy integration with the photonic and optoelectronic circuits. In this thesis, we report on a dual-gate black phosphorous photodetector based on solid polymer electrolyte for integrated photonics and optoelectronic applications. The combination of polymer electrolyte gate with the conventional back-gate black phosphorous (BP) photodetector allows for efficient control of electrical transport and carrier-density modulation in the BP channel. Our dual-gate field effect transistors provide a 50-fold enhancement in the drain currents that lead to high ON/OFF ratio as compared to the conventional SiO2 bottom gating. The BP FETs with polymer electrolyte film also protect BP flake from surface oxidation and show stable electrical characteristics under ambient conditions. The polymer electrolyte-based FETs also show an enhancement in the drain current with the orthogonal source-drain contact configuration. Photocurrent modulation by a factor of four by incident powers (varied from 0.5 to 5 mW) at a wavelength of 808 nm. At these modest powers, a factor of two modulation in the photocurrent is achieved by varying the top-gate voltage (from 3 V to -3 V). At lower powers, the dual-gate polymer electrolyte based BP photodetector shows a photocurrent a substantial enhancement of the photocurrent by 16 when the electrolyte gate voltage tuned from -2 V to 2 V as compared to the bottom gate device which is 2.5 times, when the gate voltage varied from -10 V to 10 V. Responsivities of the order of hundreds of mA/W are obtained for the BP photodetectors in both visible and NIR regimes

AN INCLUSIVE MODEL FOR ASSESSING THE QUALITY OF SERVICE IN PUBLIC SECTOR TERTIARY HOSPITALS

Quality has taken central stage in contemporary organizations and is one of the key areas of competition. Healthcare organizations, in particular, strive to provide better quality services to their patients in order to gain competitive advantage. Researchers and academicians have yet to agree on how to define and measure quality of service. Attempts have been made to develop standards and measurements to determine the degree of quality of services. However, the literature does not contain a model or standards to measure the quality of health care services. The paper in question presents an inclusive model to measure the quality of service of healthcare organizations. In addition to healthcare services (cure and care) the model encompasses teaching aspect of hospitals as well. This model was developed on the basis of an in-depth and careful study of a large (2400 bedded) public sector teaching hospital spread over a period of two years.  Data was collected from 400 patients, 250 employees, 200 general public, and 250 students through questionnaire followed by in-depth interviews. In addition to all this, various processes and interactions among individuals in the hospital were closely observed. Hospital records were studied. Anything that possibly could contribute to the quality of service in hospital was placed under one of the three dimensions of the model. Since the model has been inductively developed through data triangulation, it can safely be used to measure the quality of health care services with a good deal of accuracy

IS PRIVATIZATION A PANACEA? PRE AND POST PRIVATIZATION ANALYSIS OF FINANCIAL PERFORMANCE

The aim of this study is to examine the impact of privatization of state-owned enterprise on financial performance, employees’ satisfaction and customer satisfaction.  Pakistan Telecommunication Company Limited (PTCL) was taken as the organization for analysis. Five years pre and post-privatization financial figures were analyzed to compare the return on asset, return on equity, earning per share, net profit margin, and dividend payout. To know customer satisfaction level, the questionnaire was personally administered and 102 questionnaires complete from all respects were included for analysis. A semi-structured interview was conducted with 25 employees to determine the satisfaction level of employees. Findings of the study confirmed adverse financial performance after privatization followed by the high level of employees’ dissatisfaction. However, customer satisfaction level was high after privatizatio

HRM in the South Asian Context: A Comparison of HRM in India, Pakistan, and Sri Lanka

A recurring question in contemporary organizations is how to deal with HRM (human resource management) in the wake of globalization and an emerging knowledge economy. Many research studies have been conducted to examine the extent to which HRM practices converge and diverge in different socio-cultural contexts. National institutions and local cultures are cited as the major stumbling blocks for HRM convergence. However, it is also true that regional clusters have many things in common (cultural similarity, level of economic development, and geographical proximity etc.) make conditions that ultimately lead to isomorphism in HRM. The study in question attempts to look at the extent of convergence and divergence of HRM in India, Pakistan, and Sri Lanka that constitute one cluster. The study specifically examines various HRM practices including training, compensation, and employees’ safety in the light of recommendations of International Labor Organization (ILO). The goal of this study is to develop a model of HRM which best describes the situation in the three countries for guiding effective employment, deployment, and development of human resources

The impact of transactional and transformational leadership on job related outcomes in the nursing profession

The role of nursing is crucial for providing required cure and care to patients in hospitals. The leadership style influence nurses working abilities and job related outcomes. Considering these arguments the present study aims at examining the relationship between nursing leadership styles (i.e. transactional and transformational) and job related outcomes (i.e. commitment with organization, satisfaction with job and work performance). To do this data was collected from 206 nurses working in different hospitals of Pakistan was collected. Descriptive and inferential statistical treatment was given to analyze the data. The results of the study revealed that both the leadership styles (i.e. transactional and transformational) positively and significantly correlated with work performance, organizational commitment and job satisfaction. On the other hand, regression analysis confirms that transformational leadership study has greater impact on job satisfaction and organizational commitment as compared transactional style while, transactional leadership style has greater influence on work performance.

The impact of transactional and transformational leadership on job related outcomes in the nursing profession

The role of nursing is crucial for providing required cure and care to patients in hospitals. The leadership style influence nurses working abilities and job related outcomes. Considering these arguments the present study aims at examining the relationship between nursing leadership styles (i.e. transactional and transformational) and job related outcomes (i.e. commitment with organization, satisfaction with job and work performance). To do this data was collected from 206 nurses working in different hospitals of Pakistan was collected. Descriptive and inferential statistical treatment was given to analyze the data. The results of the study revealed that both the leadership styles (i.e. transactional and transformational) positively and significantly correlated with work performance, organizational commitment and job satisfaction. On the other hand, regression analysis confirms that transformational leadership study has greater impact on job satisfaction and organizational commitment as compared transactional style while, transactional leadership style has greater influence on work performance.Â

An Intelligent Monitoring System of Vehicles on Highway Traffic

Vehicle speed monitoring and management of highways is the critical problem of the road in this modern age of growing technology and population. A poor management results in frequent traffic jam, traffic rules violation and fatal road accidents. Using traditional techniques of RADAR, LIDAR and LASAR to address this problem is time-consuming, expensive and tedious. This paper presents an efficient framework to produce a simple, cost efficient and intelligent system for vehicle speed monitoring. The proposed method uses an HD (High Definition) camera mounted on the road side either on a pole or on a traffic signal for recording video frames. On the basis of these frames, a vehicle can be tracked by using radius growing method, and its speed can be calculated by calculating vehicle mask and its displacement in consecutive frames. The method uses pattern recognition, digital image processing and mathematical techniques for vehicle detection, tracking and speed calculation. The validity of the proposed model is proved by testing it on different highways.Comment: 5 page

The Choice of Governing Mechanism: An Organization Economics Perspective

Organization economics, with its two main strands of transaction cost economics and agency theory, primarily deals with the question of how organizations emerge and survive. It focuses on the analysis of competition within hierarchies (organizations) rather than markets and addresses questions such as why organizations exist, how they are managed, why some perform better than others, and why they tend to cooperate. This study attempts to juxtapose other relevant perspectives and organization theories to bear on the same questions. The purpose is to understand where and how organization economics and other perspectives converge and diverge. The study depends on the work of famous scholars contributing to various perspectives for drawing conclusions

IMPACT OF INTERPERSONAL JUSTICE ON ORGANIZATIONAL CITIZENSHIP BEHAVIOUR, TURNOVER AND ORGANIZATIONAL COMMITMENT WITH MODERATING ROLE OF PERCEIVED ORGANIZATIONAL SUPPORT

Abstract This paper aims at investigating the causal as well as correlational relationship between interpersonal justice (independent variable) and organizational citizenship behavior, turnover and organizational commitment (criterion variables). It also examines the moderating role of perceived organizational support. To do this data was collected from a large public healthcare organization having 3000 employees. 180 close ended questionnaires were administered to randomly selected employees and 103 questionnaire perfectly filled in from all respects were selected for analysis. Apart from descriptive statistics, correlational and regression analysis were made using SPSS.Data substantiated the existence of significant positive relationship of interpersonal justice with perceived organizational support, organizational citizenship behavior and turnover. However, its’ relationship with organizational commitment appeared insignificant. The results of this study are quite consistent with the literature.Key words: interpersonal justice perceived organizational support (POS), organizational citizenship behavior (OCB), turnover and organizational commitment.Â

Synthesis and characterization of CoFe2O4/MWCNTs nanocomposites and high-frequency analysis of their dielectric properties.

Nanoparticles of CoFe2O4 were synthesized by chemical co-precipitation method. The CoFe2O4/MWCNT nanocomposites were synthesized with increasing contents of MWCNTs, i.e., 0.0, 2.0, 3.0, and 5.0% by weight via ultrasonication method in a dispersive medium using ortho-xylene. The synthesized cobalt ferrite nanoparticles and their nanocomposites were characterized by impedance analyzer, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and x-ray diffraction (XRD) techniques. The XRD indexed patterns confirmed the face-centered cubic structure of CoFe2O4/MWCNT nanocomposites. The average crystallite size in all the samples was in the range of 15 to 35 nm. The decorations of CoFe2O4 on MWCNTs were confirmed by SEM images. The FTIR results showed two vibrational bands. With the increasing contents of multi-walled carbon nanotubes in the cobalt ferrite/MWCNT nanocomposites, the dielectric properties were also enhanced. At 1 MHz, dielectric constant, dielectric loss, and tangent loss factor were increased from 26, 15.1, and 0.580 for pure cobalt ferrite to 47, 28.9, and 0.614 for loading of 5% MWCNTs, respectively. At 1 GHz, dielectric constant, dielectric loss, and tangent loss factor were increased from 11.6, 0.33, and 0.028 for pure cobalt ferrite to 19.4, 0.61, and 0.031 for loading of 5% MWCNTs, respectively. Such a huge increase in the dielectric properties of cobalt ferrite and multi-walled carbon nanocomposites exploited their applications at high frequency