Design and development of high efficiency solar cells using thin film GaAs on nanostructured silicon

Multi-junction solar cells are being explored extensively as an alternative to long existing silicon photovoltaic technology. At present, this technology is very expensive due to high Ge and GaAs material cost, however, excellent quality GaAs thin films grown on Si substrates is an alternative route to addresses such challenges. In this report, the design and development of efficient solar cells using GaAs thin films on high aspect ratio Si nanostructures has been investigated. Such nanostructures can be used as template layers for defect reduction as well as sacrificial layers. An initial work starts with the MOCVD growth of thin films of GaAs on nanostructured Si substrate. Photoluminance studies show promising results with stronger impurity transition peak with lower full width at half maximum. Optical characterization confirms that the GaAs band-edge was consistent with crystalline GaAs substrates. An effective technique for the growth optimization on nanostructured Si surfaces can lead to improved quality material for the production of high efficiency solar cells. The fabricated devices showed promising results for commercial applications.