Fabrication of Group IIIA Layered Sulfide Semiconductor Nanostructures by Physical Vapor Deposition Process and Their En
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Fabrication of Group IIIA Layered Sulfide Semiconductor Nanostructures by Physical Vapor Deposition Process and Their Enhanced Optical and Electronic Properties Anuja Datta1, and Pritish Mukherjee1,2 1 Florida Cluster for Advanced Smart Sensor Technologies & Department of Physics, University of South Florida, Tampa, Fl 33620, USA. 2 Center for Integrated Functional Materials & Department of Physics, University of South Florida, Tampa, Fl 33620, USA. ABSTRACT We report on the fabrication of various high quality GaS nanostructures (angular nanobelts, nanowedges and nanotubes) and In 2 S 3 nanostructures (tapered nanorods, nanobelts and nanowires) by catalyst assisted thermal evaporation process. The morphology and structures of the products were controlled by temperature and position of the substrates with respect to the source material. The morphologies of GaS and In 2 S 3 nanostructures were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and energy dispersive spectroscopy (EDS). The optical and electronic properties of the synthesized materials were investigated in order to obtain a better fundamental understanding of the structure-property relationships in these materials which can be extended to other layered sulfide materials systems. INTRODUCTION The design and fabrication of nano-structured materials is one of the most important and interesting subjects for creating advanced functional devices. As the material approaches the nanometer size regime, new properties are expected that are not only dependent to the size but also to the shape of the nanocrystals [1]. One of the most extensively studied groups of compounds for this purpose is sulfide materials [2]. These semiconductors possess a variety of crystalline phases depending largely on the atomic radius ratios and electronegativity differences of the constituent atoms [3]. Crystalline metal chalcogenide semiconducting nanocrystals show high luminescence quantum efficiency [4], size independent emission color [3,4], and enhanced electrical properties [5]. Additionally, sulfide semiconductor nanomaterials with layered crystal structures are very attractive because they have strong intra-layer covalent bonding and interlayer weak Van der Waals interaction, which lead to attractive photovoltaic and optoelectronic applications [3,4, 6-10]. Considerable progress has been made in the past few years towards the fabrication of different layer-structured group III semiconductors in various nano-forms via chemical and physical processing techniques in controlled manner, among which gallium sulfide (GaS) and indium sulfide (In 2 S 3 ) are most important materials with promises of applications in optics and electronic technologies. [6-11] Oriented nanostructures of these layered sulfide materials are highly desirable, but direct fabrication of the nanostructures with controlled morphology, orientation and surface architectures is of significant challenge. Physical vapor deposition process
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