CAMP June Newsletter: Page 6
Synthesis and Mechanical Property Characterization of Silicon Nanowires
CAMP Professors Weiqiang Ding and Daryush Aidun and graduate student Huan Zhang, of Clarkson's Department of Mechanical and Aeronautical Engineering, are working on the synthesis of silicon nanowires for photovoltaic solar cell applications. Silicon is a key material for the semiconductor industry. In recent years, nano-sized silicon wires have been intensively studied for photovoltaic, photo-electrochemical and optoelectronic applications. In this project, silicon nanowires were synthesized through a vapor-solid process at an elevated temperature by using a home-built low pressure chemical vapor deposition system. See Figure 2. Silicon nanowires were grown on a catalyst-coated silicon substrate with commercial silicon powder as the starting material. The silicon nanowires were characterized with scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray powder diffraction. The mechanical properties of the silicon nanowires will be characterized with nanoscale tensile testing and mechanical resonance methods by using a home-built nanomanipulation system inside the vacuum chamber of a scanning electron microscope.
Figure 2. (a) Silicon nanowire synthesis setup; (b) Scanning electron microscope image of silicon nanowires grown on a silicon substrate.
Professor Daryush Aidun (Chair of Clarkson University's Department of Aeronautical and Mechanical Engineering) and his group designed and made a solar welding system, known as DKA Solar Welder. His group includes Professor James Kane (of Clarkson's Department of Mechanical and Aeronautical Engineering) and students James Callahan, Scott Cary, Glenn Crans, Tyler Hallings, Tim Hatcher, Matt McGonigal, and Ben O'Dell.
The students belong to the welding Metallurgy and the Integrated Design class (ME 445/446) taught by Professor Kane. The original design idea for the class was to show that solar energy can be used for fabrication processes such as joining and surface heat treatment/modification. The pictures of the solar welder show that direct sunlight can be used for joining two 1 mm aluminum sheets. This task can also take place in remote areas that have lots of sunlight. Some advantages to this method are that it has no electric arc, no electric shock, no welding fumes, and no spatter. Also nonconductors can be welded and both sides of a metal can be welded simultaneously.
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In addition, solar energy storage systems can be used such as PV to store the electric energy until it is needed for welding. However, in this case the process will resemble arc welding, which presents safety issues and fumes that are associated with conventional arc welding processes.