Date of Award

4-2013

Document Type

Thesis

Degree Name

Master of Science in Material Science Engineering (MSMatSE)

Department

Materials Science

First Advisor

Dr. Ah m a d I. Ayesh

Second Advisor

Prof. Yousef Haik

Third Advisor

D r . Dagou Zeze

Comments

This research focuses on the fabrication and characterization of silicon (Si) and silver (Ag) nanoclusters that might be used for solar cell applications. Silicon and silver nanoclusters have been synthesized by means of inert gas condensation method and dc magnetron sputtering source inside an ultra-high vacuum system. The nanocluster source produces ionized nanoclusters that enable the study of the nanocluster size distribution using a quadrupole mass filter (QMF). We have found that nanocluster size distribution can be tuned by various source parameters, such as the sputtering discharge power (P), argon inert gas flow rate (FAr), and aggregation length (L).

Transmission electron microscopy (TEM) have been done to evaluate the size distribution of Si and Ag nanoclusters and to confirm the measurements performed using the quadrupole mass filter results. The Si nanocluster size distributions were controlled to change in the range of 3.33 ± 0.27 to 7.36 ± 0.52 nm by controlling the source conditions. On the other hand, Ag nanoclusters with average size in the range of 3.65 ± 0.05nm to 8.25 ± 0.15 nm were synthesized by altering the source conditions. This work illustrates the ability of controlling the Si and Ag nanoclusters' size by proper optimization of the operation conditions. By controlling the Si and Ag nanoclusters size, one can alter their surface properties to suit our needs to enhance the solar cell efficiency. The current work also discusses the nanocluster formation mechanisms. Herein, Ag nanoclusters were deposited on commercial polycrystalline solar cells. Short circuit current (ISC), open circuit voltage (VOC), fill factor (FF), and efficiency (η) were obtained under light source with an intensity of 30 mW/cm2. A 22.7% enhancement in solar cell efficiency could be measured after deposition of Ag nanoclusters which demonstrates that Ag nanoclusters generated in this work are useful to enhance solar cell efficiency. The research has underlined promising results and many other ideas that can be implemented in the future for solar cell applications.

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