Optical Transitions in Amorphous Semiconductors

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dc.contributor.advisor O'Leary, Stephen
dc.contributor.author Orapunt, Farida
dc.date.accessioned 2012-11-23T21:38:24Z
dc.date.available 2012-11-23T21:38:24Z
dc.date.issued 2012-04
dc.identifier.uri http://hdl.handle.net/10294/3648
dc.description A Thesis Submitted to the Faculty of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Engineering, University of Regina, xlii, 211 l. en_US
dc.description.abstract In this thesis, a quantitative analysis of the optical response of an amorphous semiconductor is presented. The entire analysis is cast within the framework of an empirical model for the valence band and conduction band density of states functions, that captures the basic features expected of these functions. A novel aspect of this analysis is the introduction of the density of localized valence band and conduction band electronic states and the establishment of a means of evaluating these densities from knowledge of the density of states functions coupled with the locations of the valence band and conduction band mobility edges. The determination of the contributions to the joint density of states function attributable to the various types of optical transitions, as a function of the location of these mobility edges, is another novel feature of this analysis. This formalism is then applied in order to determine the spectral dependence of the normalized dipole matrix element squared average corresponding to such a semiconductor. A means of determining the spectral dependence of the optical absorption coefficient is also provided. Finally, this formalism is applied to the specific case of plasma enhanced chemical vapor deposition deposited hydrogenated amorphous silicon, this being the most widely used amorphous semiconductor at present. It is found that the mobility gap value suggested by Jackson et al. [Physical Review B, vol. 31, pp. 5187-5198, 1985] is discordant with the experimentally measured optical response. It is also found that the effective masses associated with the electrons and holes within plasma enhanced chemical vapor deposition are greater than those that occur in crystalline silicon. The prospects for future work in this field, that builds upon the results presented herein, are commented upon. en_US
dc.description.uri A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy *, University of Regina. *, * p. en
dc.language.iso en en_US
dc.publisher Faculty of Graduate Studies and Research, University of Regina en_US
dc.subject.lcsh Amorphous semiconductors--Optical properties
dc.title Optical Transitions in Amorphous Semiconductors en_US
dc.type Thesis en
dc.description.authorstatus Student en
dc.description.peerreview yes en
thesis.degree.name Doctor of Philosophy (PhD) en_US
thesis.degree.level Doctoral en
thesis.degree.grantor University of Regina en
thesis.degree.department Faculty of Engineering and Applied Science en_US
dc.contributor.committeemember Benedicenti, Luigi
dc.contributor.committeemember Laforge, Paul
dc.contributor.committeemember Palmer, Ron
dc.contributor.committeemember Huber, Garth
dc.contributor.externalexaminer Sabarinathan, Javshri


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