III-V Nanostructures Grown by Molecular Beam Epitaxy for High Efficiency Solar Cells

Semiconductor nanostructures have demonstrated great potential in energy harvesting due to their unique optical and electrical properties compared to their bulk counterparts. Particularly, self-assembled semiconductor nanostructures have received much attention in the last decade. For example, zero-dimensional (0D) quantum dots (QDs) with discrete energy levels like atoms have been proposed to realize high efficient photovoltaic devices that employ novel concepts including hot carriers, intermediate band, and multiple exciton generation. In addition, one-dimensional (1D) nanowires (NWs) can not only facilitate effective charge separation but also form nanophotonic structures that enable enhanced light absorption through light trapping. Moreover, the small footprint of NWs has a high tolerance to thermal and lattice mismatch and hence, integration of materials with different structural properties is possible to implement complex device architecture for high efficiency solar cells.  In this presentation, we introduce our developments in nanomaterial growth by using solid-state molecular beam epitaxy and the applications of these self-assembled semiconductor nanostructures in photovoltaic applications. Emphasis will be put on design of III-V QDs  for intermediate band solar cells as well as growth of III-V NWs on silicon for cost-effective high efficient solar cells.