This thesis examines the luminescence properties of nanoscale silicon (Si) by
using spectroscopic techniques. Since the development of new optical devices
requires understanding light emission mechanism optical spectroscopy has
become more important tool in the analysis of these structures. In this thesis, Si
nanocrystals embedded in SiO2 matrix will be studied.
Photoluminescence (PL) and Time-resolved photoluminescence spectroscopy
(TRPL) have been used to detect the light emission in UV-Vis-NIR range.
Experiments have been performed in the temperature range 10-300 K. PL is
sensitive to impurities and defects that affect materials quality and device
performance. In this context, the role of defects in limiting the luminescence of Si
nanocrystals and the removal of these defects by hydrogen passivation has been
investigated.
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TRPL was employed to determine the time evolution of photoluminescence as
function of temperature. The decay time of the PL spectra was determined by a
stretched exponential function and perfectly fitted to an expression based on three
excitonic levels. Carrier lifetimes associated with these three levels were
determined and compared with literature.
Additionally, temporal variation of PL from free-standing Si nanoparticles is
studied under a strong laser illumination. The observed bleaching behavior (time
dependent emission intensity), which is reversible, have discussed in terms of
exciton trapping at the interface between nanocrystal and the surrounding oxide
layer.
The results of this thesis will provide new insight on the understanding of light
emission mechanism of Si nanocrytals.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12611750/index.pdf |
| Date | 01 March 2010 |
| Creators | Seyhan, Ayse |
| Contributors | Turan, Rasit |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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