This Small Business Innovation Research Phase I project will assess the feasibility of a new fabrication method for high-density p-n silicon nanocable arrays using CVD techniques. This project aims to create grow p-silicon nanowire arrays using a patterned mask that will enable highly ordered and perfectly oriented nanowires, which cannot be achieved through conventional methods. On these nanowires, CVD will be used to grow n-silicon layers radially, resulting in high-quality single-crystal structures. The aim is to demonstrate high quality semiconductor junctions integrated in a nanocable array structure. Techniques to control and characterize the p-n Si nanocables obtained by CVD are the primary focus of this proposal. It is the only technology known that may allow controlled orientation of nanostructures and integration of the p-n junction in the nanowire itself, with precision growth that prevents structures from shorting against one another. Techniques to control and verify the quality of surfaces and interfaces are especially important when the subsequent layers are extremely thin, as is the case in this solar cell design. The results lay the foundation for creating highly-flexible nanostructure array templates and arrays.
Although targeted at solar cells, this research has broad applicability in nanoelectronics and nanofabrication. The result will be arrays of complex nanostructures that can be insulated from one another. Controlling the quality, composition and dimensions of nanowires that allow ultra-thin layers deposited thereon allows creating nanostructured materials that are tunable for key nanoscale properties at low cost. This enables applications not possible with bulk materials. These processes should allow low-cost continuous fabrication of nanostructure of dimensions and density not possible using current commercial membranes. Nanostructured devices, rather than bulk materials, are the key to realizing economical, reliable, high performance solar cells. Results will be arrays of discrete structures but the same techniques are applicable to circuitry, sensors, and optical applications.
