GROWTH AND INVESTIGATION OF GROUP II-VI SEMICONDUCTOR NANOPARTICLES FOR LUMINESCENCE BASED APPLICATIONS

Abstract

Introduction The work presented in the thesis focused on zero-dimensional II-VI semiconductor-based luminescent materials, including zinc-based un-doped and transition metals doped/co-doped luminescent nanoparticles. The chapter mainly gives a brief introduction to the nanomaterials and classifications based on the confinement of the system. Also, it introduces 0-D II-VI semiconductor quantum dots, specifically zinc selenide quantum dots (ZnSe QDs) and their properties, as well as focused on important applications of these materials in various sensing areas purposes, like hazardous toxic heavy metals, explosive compounds and temperature sensors. 1.1 Nanomaterials Physics and chemistry have experienced significant development in the nanometer size range, leading to a new interdisciplinary field of nanoscience in the last decade. The attention in nanoscale materials increases because many physical phenomena occur at a length scale between 1 and 100 nm in both organic and inorganic materials. Nanoparticles are microscopic particles having a dimension below 100 nm at least in one direction. A drastic change in the various properties of materials is observed as nanoscale size is achieved and a significantly high number of loosely bonded atoms present at the material surface. Numerous size-dependent properties are detected in nano regime such as super paramagnetism in magnetic substances, quantum confinement in semiconductor particles and surface plasmon resonance in some metal particles [1]. Typically, nanoparticles have possessed excellent and unpredictable optical properties due to the applicability of quantum effects which arises because of 2 sufficiently small confinement of their electrons. When one or more than one dimension of a material is reduced to the nanoscale, its physicochemical properties are remarkably changed from the bulk counterpart. With the size reduction, novel optical, magnetic, chemical, mechanical and electrical properties can be introduced. Then, the resulting size-reduced systems are called low-dimensional systems. In the low-dimensional structures, the confinement of particles, i.e., electrons or holes, leads to the manifestation of size effects and dramatic changes in the properties or behaviour of the materials, which generally comes into the quantum-size effects [2]. Nanostructures play the role of bridge between the molecules and bulk materials. Nanostructures can lead to new technologies and devices by suitable control of the properties and responses.