Research On GaAs Nanowire Solar Cell

With the use of petroleum and coal, global warming and air pollution have become critical problems, especially those limited non-renewable resources of energy has led to intensified war, forced people to focus on the development of new energy technologies. For its cleanliness, safety, adequacy and potential of the economy, solar cells have attracted widespread attention; the study of solar photovoltaic devices has become a hot topic in the academic field.Solar cells can be divided into three generations:the first generation of crystalline solar cells, the second-generation thin-film solar cells, and the third generation solar cells with high conversion efficiency. The first generation includes monocrystalline and polycrystalline solar cells, and is the most matured technology. However, the biggest problem for crystalline silicon solar cells is the requirement of high purity silicon, which makes the capital investment and energy loss relatively large. And because of silicon's band gap constraints, high-energy part of the spectrum or blue-violet light is wasted. The second-generation solar cell includes cadmium telluride, copper indium gallium selenide and other types. Such solar cell can be coated with low-cost technology for large-scale production, but its conversion efficiency can only reach about 10%. In addition, the stability of thin film materials is poorer than silicon, and the high toxicity of these materials is also a big problem. The third-generation includes multi-junction, middle band and carrier multiplication type, but only multi-junction is currently applied to the real product. With the rapid development of nanotechnology, the design of solar cells with nanotechnology will become a new trend. The research of the GaAs nanowire solar cell belongs to the scope of the third generation solar cells.Our research group has cooperated with McMaster University in the field of group III-V compound semiconductor nanowires based manufacturing process development of the most advanced photovoltaic cells, and will create a GaAs-based nanowire solar cell using the radial p-n junction with better light absorption and photo-carrier collection, making conversion efficiency improvement obviously.This article describes two methods of making GaAs nanowires:VLS growth mechanism and dry etching method. Both methods have their advantages, those GaAs nanowire samples can both be used for the production of solar cells. This article also introduce two different GaAs nanowire solar cell production processes, and point out the existing process deficiencies, give proposals for improvement, as future research directions.