A Phenomenological Model to Investigate Excitonic Effects on Photoluminescence intensity of Nanosilicon
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Date
2009-06
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Addis Ababa University
Abstract
Visible photoluminescence from nano-silicon is one of the most attractive and debatable
issue in recent years. Studying photoluminescence and understanding its
mechanism has tremendous attention due to optoelectronic applications. When the
size of quantum dots decreases the surface area to volume ratio increases and localized
surface states appears in the forbidden region. Exciton energy states are also exists
in the same gap region. It is important to examine the combined e ects of exciton,
localized surface states and quantum con nement e ects. We have explicitly integrated
these e ects in a phenomenological model to obtain analytical expression for
the photoluminescence spectra. Initially, we explicitly calculated the exciton binding
energy and we incorporate the exciton contribution then combined it with quantum
con nement model and surface states to see its e ect on photoluminescence. Accordingly,
we observed that taking the e ect of exciton states into account explains
almost accurately the experimental photoluminescence data. The results obtained using
MATLAB programming. Calculations take place at room temperature on small
quantum dots (1 - 5 nm). In conclusion, our results are quite new and it re
ect some
of the feature that has quite close correspondence with the experimental. The results
are also in conformity with other theoretical and experimental investigations
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Phenomenological Model