Estimation of Absorption Coefficient, Oscillator Strength and Dielectric Function of Small Silicon Nanocrystallites

Gesese, Anley (2009) Estimation of Absorption Coefficient, Oscillator Strength and Dielectric Function of Small Silicon Nanocrystallites. Masters thesis, Addis Ababa University.

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Abstract

Even if bulk silicon is poor emitter of light, due to quantum size effect which leads to an increase (the blue shift) of the band gap of the crystallites compared to bulk silicon, silicon nanostructure (porous Silicon, quantum dots, quantum wells and nanoclusters ) exhibit strong photoluminescence at room temperature. Nanosilicon research is gaining tremendous attention in recent years towards the possibility of photonic application. In order to explain optical properties of nanoporous semiconductor i.e the variation of absorption coefficient, dielectric constant and oscillator strength with size of nanoporous semiconductor information about the density of states which depends on the dimensionality of the system is very important. To do so, we obtain the density of states for 3-D, 2-D and 1-D and the dipole matrix element with the help of Kane approximation of momentum matrix element of direct band gap semiconductors. Using the dipole matrix element together with the joint density of states between valence and conduction band states we calculate the optical absorption coefficient, imaginary part of the dielectric function as well as the oscillator strength near the band edge for nanoporous semiconductor thus we find that the optical absorption coefficient and the imaginary part of the dielectric function are explicit function of photon energy and band gap energy but implicit function of the nanoporous semiconductors size through band gap energy. Our results for these optical parameters are in conformity with other observations.

Item Type:	Thesis (Masters)
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Divisions:	Africana
Depositing User:	Selom Ghislain
Date Deposited:	16 Aug 2018 08:54
Last Modified:	16 Aug 2018 08:54
URI:	http://thesisbank.jhia.ac.ke/id/eprint/4790

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