III-V Semiconductor Nanowire Solar Cells

This chapter reviews the implementation of semiconductor nanowires as the active optical elements of nanowire-based photovoltaics. Some essential principles for understanding the semiconductor p-n junction photoresponse are briefly covered, followed by a more detailed presentation of the arguments for turning to a nanowire geometry rather than the traditional planar case. These include the decoupling of the light absorption and carrier collection directions for a radial junction geometry, the relaxation of lattice-mismatching constraints in choice of material combinations for axial heterojunctions, and absorption enhancement via light scattering in nanowire arrays. The emphasis here is on semiconductor nanowires grown epitaxially from a substrate, rather than solution-based methods. Because of the application-oriented nature of the material discussed, though, this scientific literature review is complemented by some remarks on the relevant patent literature for this field, also including alternative synthesis methods, as a gauge of the readiness for moving from scientific research to technology development. Finally, an outlook on additional modifications or integrations into the semiconductor nanowire solar cell framework is presented, such as the incorporation of plasmonic cell elements.

Keywords: Nanowires, III-V semiconductors, solar cell, photovoltaics, third generation, heterostructures, light trapping.