Investigation of multilayer thin films using ellipsometry

Light emission from silicon-based materials is a very important research area for optoelectronic and display applications. It is important to derive a practical light source from silicon in order to have complete photonic integrated circuits on silicon. An efficient silicon based light emitting device would revolutionize the silicon photonics field, and thus numerous efforts have been undertaken to develop silicon as a viable optical material. Not only will the Silicon based light source be able to provide an easy route to integrate with silicon electronics but also be compatible with current fabrication technology. In this work, the optical properties of a-SiNx:H/Si02 multi layers thin films have been investigated using spectroscopic ellipsometry (SE). Plasma Enhanced Chemical Vapor Deposition (PECVD) was used to fabricate multilayer thin films. The ellipsometric data was acquired using a rotating analyzer J. A. Woollam variable angle spectroscopic ellipsometer in the wavelength range of 270 nm to 1700. The SE experiments conducted were quite extensive in terms of the range of energy and the angles at which the measurements were performed. SE itself is not a direct readout type technique. It is actually a model-based technique. Thus, it is important to build correct and suitable model for a particular material in the SE fitting. In this project, several dispersion models are investigated to find the one which is best suitable for the fitting of a-SRN. The fitting of the ellipsometric data was carried out using the WVASE32™ software. Several samples were characterized using SE and the data were fitted by software Wvase32 using two dispersion models: Tauc-Lorentz (TL) model and TL with the inclusion of the Urbach tail. Optical constants for the single layer as well as multilayer thin films were obtained using both TL and TLU models. The optical constants obtained from both the models have been compared. Thickness of the films, barrier and bulk layer obtained through SE have been compared with the TEM results and are found to be in agreement with each other, thus verifying the accuracy of the SE results. Results obtained from both the models were also compared and it was observed that TLU gave better results.Master of Science (Electronics

Contextual Bandit Approach-based Recommendation System for Personalized Web-based Services

In recent years, recommendation systems have started to gain significant attention and popularity. A recommendation system plays a significant role in various applications and services such as e-commerce, video streaming websites, etc. A critical task for a recommendation system is to model users’ preferences so that it can attain the capability to suggest personalized items for each user. The personalized list suggested by a suitable recommendation system should contain items highly relevant to the user. However, many a times, the traditional recommendation systems do not have enough data about the user or its peers because the model faces the cold-start problem. This work compares the existing three MAB algorithms: LinUCB, Hybrid-LinUCB, and CoLin based on evaluating regret. These algorithms are first tested on the synthetic data and then used on the real-world datasets from different areas: Yahoo Front Page Today Module, Lastfm, and MovieLens20M. The experiment results show that CoLin outperforms Hybrid-LinUBC and LinUCB, reporting cumulated regret of 8.950 for LastFm and 60.34 for MovieLens20M and 34.10 for Yahoo FrontPage Today Module

Electric vehicles for low-emission urban mobility: current status and policy review for India

Urban areas account for around 70% of global GHG emissions, one-third of which is attributed to the transportation sector. Thus, decarbonising urban mobility is critical in the endeavours to mitigate climate change. Electric vehicles (EV) have potential to control global decarbonisation of transportation. India has air quality index of 141, which is amongst the highest in the world. Considering this troubling figure, government has initiated various schemes and initiative plans. This study reviews the progress and current status of EV adoption in India with regard to availability, manufacturing, charging infrastructure, commercial vehicle electrification and in-depth analysis of FAME-I and FAME-II schemes along with state level initiatives. This research explores the current state of EV adoption through the integrative perspective of financial resources, infrastructure and technology availability highlighting various complications. Based on these challenges, the study proposes points of improvment in each fragment such as policies, infrastructure,electricity demand and sustainable source of energy. A roadmap is recommended of primary factors that should be priortised for effective EV adoption