NSF Award
9760805
*** 9760805 Jones This Small Business Innovation Research Phase I project will test the feasibility of using a novel Microwave/Electron Beam (EM) Gas Jet technique to prepare high stable efficiency microcrystalline silicon cells at high deposition rates. These cells, with light absorbing microcrystalline layers, have been proposed as an alternative to amorphous silicon based cells because, in contrast to the amorphous cells, the efficiencies do not degrade with long term light exposure. While microcrystalline cells with 11% stable efficiencies have been obtained, the technique used to prepare these cells requires unacceptably low deposition rates of 1-3 A/s for microcrystalline formation. The proposed technique is unique in that it utilizes a microwave source, an electron beam and a Gas Jet that produces near supersonic gas speeds. The microwaves efficiently decompose the silane gas to create high deposition rates and with large amounts of hydrogen dilution generate large atomic hydrogen fluxes that are important for microcrystalline formation. The electron beam is required to stabilize the plasma while high gas speeds created by the Gas Jet minimize any detrimental gas phase interactions. The proposer will demonstrate in this program that high quality microcrystalline silicon materials and solar cells can be prepared at high rates with this novel deposition technique. The success of this program will ultimately lead to a wider use of Photovoltaic (PV) products thereby reducing the dependency on fossil fuel energy sources. Development of a high deposition rate technique to prepare high quality microcrystalline silicon could also be applied in other industries such as thin film transistors, photodetectors, and photosensors. ***
