Nanometer-scale silicon shows extraordinary electronic and optical properties that
are not available for bulk silicon, and many investigations toward applications in optoelectronic
devices are being pursued. Silicon nanoparticle films made from solution
are a promising candidate for low-cost solar cells. However, controlling the properties
of silicon nanoparticles is quite a challenge, in particular shape and size distribution,
which effect device performance. At present, none of the solar cells made from silicon
nanoparticle films have an efficiency exceeding the efficiency of those based on crystalline
silicon. To address the challenge of controlling silicon nanoparticle properties,
both theoretical and experimental investigations are needed. In this thesis, we investigate
silicon nanoparticle properties via quantum mechanical modeling of silicon
nanoparticles and synthesis of silicon nanoparticle films via colloidal grinding.
Silicon nanoparticles with shapes including cubic, rectangular, ellipsoidal and flat
disk are modeled using semi-empirical methods and configuration interaction. Their
electronic properties with different surface passivation were also studied. The results
showed that silicon nanoparticles with hydrogen passivation have higher HOMOLUMO
gaps, and also the HOMO-LUMO gap depends on the size and the shape
of the particle. In contrast, silicon nanoparticles with oxygen passivation have a
lower HOMO-LUMO gap. Raman spectroscopy calculation of silicon nanoparticles
show peak shift and asymmetric broadening similar to what has been observed in
experiment.
Silicon nanoparticle synthesis via colloidal grinding was demonstrated as a straightforward
and inexpensive approach for thin film solar cells. Data analysis of silicon
particles via SEM images demonstrated that colloidal grinding is effective in reducing
the Si particle size to sub-micron in a short grinding time. Further increases in
grinding time, followed by filtration demonstrated a narrowing of the Si particle size
and size-distribution to an average size of 70 nm. Raman spectroscopy and EDS data
demonstrated that the Si nanoparticles contain oxygen due to exposure to air during
grinding. I-V characterization of the milled Si nanoparticles showed an ohmic behaviour
with low current at low biases then Schottky diode behaviour or a symmetric
curve at large biases. / Graduate / 0794 / 0544 / zahraalbu@hotmail.com
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/5344 |
| Date | 30 April 2014 |
| Creators | Albu, Zahra |
| Contributors | Papadopoulos, Christo |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web, http://creativecommons.org/licenses/by-nc-nd/2.5/ca/ |
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