UBC Theses and Dissertations
An analysis of the optical response of amorphous semiconductors with distributions of defect states Chowdhury, Shamsul Azam
Defects play an important role in shaping the optical response of a semiconductor material. In this thesis, models for the spectral dependence of the imaginary part of the dielectric function, for the specific case of defective amorphous semiconductors, are considered. Within the framework of a joint density of states functional analysis, closed-form expressions are derived for the imaginary part of the dielectric function, with defect states taken into account. Both valence band and conduction band defect models are considered in this analysis. The role that the different types of optical transitions play in shaping the corresponding optical response are also closely examined. Using the derived models, the spectral dependence of the optical absorption coefficient is compared with that of experiment for defect absorption influenced samples of amorphous silicon. The fits of these models with the results of experiment are found to be satisfactory.
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