Nanocrystalline Si is a mixture of crystalline Si nanocrystals in an amorphous Si matrix. Time resolve terahertz spectroscopy shows carriers excited in the amorphous regions quickly transfer to localized states on the surfaces of the nanocrystals before they can relax in the amorphous regions. Carriers are remitted to the conduction band improving mobility. Because carriers do not recombine in the amorphous silicon, optical degradation is reduced. This is the first observation of hot carrier transfer in an amorphous system opening up a new paradigmn for the design of hot carrier solar cells.
