Show simple item record

dc.contributor.advisorChaieb, Saharoui
dc.contributor.authorMughal, Asad Jahangir
dc.date.accessioned2012-05-07T12:05:56Z
dc.date.available2013-05-30T00:00:00Z
dc.date.issued2012-05
dc.identifier.citationMughal, A. J. (2012). Synthesis and Characterization of Chemically Etched Nanostructured Silicon. KAUST Research Repository. https://doi.org/10.25781/KAUST-FB33Z
dc.identifier.doi10.25781/KAUST-FB33Z
dc.identifier.urihttp://hdl.handle.net/10754/222131
dc.description.abstractSilicon is an essential element in today’s modern world. Nanostructured Si is a more recently studied variant, which has currently garnered much attention. When its spatial dimensions are confined below a certain limit, its optical properties change dramatically. It transforms from an indirect bandgap material that does not absorb or emit light efficiently into one which can emit visible light at room temperatures. Although much work has been conducted in understanding the properties of nanostructured Si, in particular porous Si surfaces, a clear understanding of the origin of photoluminescence has not yet been produced. Typical synthesis approaches used to produce nanostructured Si, in particular porous Si and nanocrystalline Si have involved complex preparations used at high temperatures, pressures, or currents. The purpose of this thesis is to develop an easier synthesis approach to produce nanostructured Si as well as arrive at a clearer understanding of the origin of photoluminescence in these systems. We used a simple chemical etching technique followed by sonication to produce nanostructured Si suspensions. The etching process involved producing pores on the surface of a Si substrate in a solution containing hydrofluoric acid and an oxidant. Nanocrystalline Si as well as nanoscale amorphous porous Si suspensions were successfully synthesized using this process. We probed into the phase, composition, and origin of photoluminescence in these materials, through the use of several characterization techniques. TEM and SEM were used to determine morphology and phase. FT-IR and XPS were employed to study chemical compositions, and steady state and time resolved optical spectroscopy techniques were applied to resolve their photoluminescent properties. Our work has revealed that the type of oxidant utilized during etching had a significant impact on the final product. When using nitric acid as the oxidant, we formed nanocrystalline Si suspensions composed of particles with a crystal structure different than the common polymorph of Si. These particles emitted UV to blue wavelengths. Iron(III) chloride was also employed as an oxidant, and it created amorphous Si nanostructures from a bulk crystalline Si source. These suspensions showed ultra-bright visible photoluminescence, which could be tuned through engineering the surface.
dc.language.isoen
dc.subjectSilicon
dc.subjectnanostructures
dc.subjectporous
dc.subjectamorphous
dc.subjectphotoluminescence
dc.subjectetching
dc.titleSynthesis and Characterization of Chemically Etched Nanostructured Silicon
dc.typeThesis
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.rights.embargodate2013-05-30
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberBakr, Osman
dc.contributor.committeememberOoi, Boon S.
thesis.degree.disciplineMechanical Engineering
thesis.degree.nameMaster of Science
dc.rights.accessrightsAt the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2013-05-30.
refterms.dateFOA2013-05-30T00:00:00Z


Files in this item

Thumbnail
Name:
A_Mughal_Thesis_May'12.pdf
Size:
3.625Mb
Format:
PDF
Description:
PDF file

This item appears in the following Collection(s)

Show simple item record