Zero Phonon And Phonon Assisted Radiative Transition Rates Based On Finite Potential Well Approximation For Silicon Nanocrystallite Embedded In Silicon Oxide

The purpose of this thesis was to study phonon assisted and zero phonon radiativernlifetimes of electron-hole pair which are excited and recombine inside nc-Si, on thernbasis of more realistic assumption of finite potential well and envelope wave approximationsrnfor oxidized PS and nc-Si inside SiO2. Finite potential well approximationrnresults the spread of conduction and valence band edge wave functions in to SiO2.rnSolving time independent Schr¨odinger equation in the two materials and applyingrnmatching boundary condition at the interface for envelope wave function part; wernfound bandgap energy closer to experimental results that increase at lower rate asrnwe shrink the size of nc-Si compared to infinitely deep potential well approximation.rnRadiative rates for both zero phonon and phonon assisted transitions are calculatedrnwith the newly developed wave functions and by separately calculating momentumrnoverlap factor and incorporating it into momentum matrix elements by hand. Newrnradiative lifetime estimation in the order of nanosecond for nc-Si size below 2 nm isrnfound. We also found μs order of life time for phonon assisted recombination raternbelow 2 nm size of nc-Si. However, the value we got for phonon assisted radiativerntransition rate does not show any significant difference from infinitely deep potentialrnwell approximation results

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