Plasmon-Enhanced Photoconductivity in Amorphous Silicon Thin Films by Use of Thermally Stable Silica-Coated Gold Nanorods

Enhancement of solar photovoltaics by integrating tells with metal nanopartides is of potential interest to reduce the usage of semiconductor material. Appropriately shaped, metal particles to optimize spectral response have inadequate thermal stability to withstand standard semiconductor processing. We synthesize silica-capped gold nanorods that maintain nonspherical shapes to over 600 degrees C and show that they can increase photoconductivity in thin films of amorphous silicon by much more than a factor of 2 across the entire visible spectrum. We also report mechanistic studies of this phenomenon that show that much of this effect is primarily due to strong near-field light concentration rather than scattering as has often been assumed.