Date of Publication

9-9-2011

Document Type

Master's Thesis

Degree Name

Master of Science in Physics

Subject Categories

Physics

College

College of Science

Department/Unit

Physics

Thesis Adviser

Gil Nonato C. Santos

Defense Panel Chair

Lydia S. Roleda

Defense Panel Member

Emmanuel T. Rodulfo
Ivan B. Culaba

Abstract/Summary

Bi2S3 Nanowires were successfully and efficiently fabricated using Horizontal Vapor Phase Crystal growth technique for photosensor application.In the synthesis, thirty five milligram with purity of 99.9 percent of bismuth sulfide was utilized. The parameters included the growth temperature, growth time and ramp time. Growth temperature was set 600 oC, 800 oC, 1000 oC, and 1200 oC.Growth time was set to 4 hours, 6, hours, and 8 hours. Ramp time was taken to be the constant parameter set at 60 minutes. he as-prepared products were characterized through the use of Scanning Electron Microscope (SEM), Energy Dispersive X-ray, and Applied Spectral Imaging.SEM was used to investigate the surface topography and morphology. Energy Dispersive X-ray was employed for determining the elemental composition. Applied Spectral Imaging was utilized for the optical property analysis.

Bismuth Sulfide Nanowires had an optimum growth at highest temperature, and lowest growth time deposited in wider area on zone 2 of a fused silica tube. Bi2S3 Nanowires which had almost uniform, horizontal in orientations, and wider area covered in deposition were the key factors of choosing them as the optimum parameters to facilitate the application of the material. Analyses of the data supported the growth mechanism of semiconductor islands self-assembled Bismuth Sulfide nanomaterials specifically, the Stranski Krastanov growth mode for the development of the three dimensional nanostructures. Energy band gap of the Bismuth Sulfide nanowires synthesized via HVPC was 2.58 eV which were blue shifted compared to its energy gap in a bulk form, 1.3 eV. Since absorption of white light was possible only if the band gap of the material fell within the range of 1.8 eV up to 3.1 eV, therefore, it could detect white light due to the manifestation of quantum confinement effect. For the fast response of the material, oxygen chemisorption played the central role in this case. The Bismuth Sulfide nanowires, then, successfully demonstrated its functionality as photosensor in a metal-semiconductor-metal planar structure since it responded with higher voltages compared to nanoleaves based on the voltage time spectra obtained using the experimental set-up made. Thus quantum confinement effect was also evident here. As it suggested therefore, bismuth sulfide nanowires could be used as photosensor in an optical devices.

Abstract Format

html

Language

English

Format

Electronic

Electronic File Format

MS WORD

Accession Number

CDTG005049

Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

91 leaves : ill. ; 1 computer optical disc

Keywords

Nanowires; Bismuth

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