Surface plasmon effect of Ag nanodots embedded in amorphous Si window layers deposited on Si solar cells

We investigated solar cells containing temperature-dependent Ag nanodots embedded in an amorphous Si thin film layer by using hot-wire chemical vapor deposition in order to improve the properties of crystalline Si solar cells. An Ag thin film with a thickness of 10 nm was deposited by DC sputtering followed by annealing at various temperatures ranging from 250 to 850 degrees C for 15 min under N2 gas. As increasing the annealing temperature, the Ag nanodots were enlarged and the photoreflectances of the samples with Ag nanodots were lower than the reference samples in the spectral range of 200-600 nm, demonstrating the plasmon effect of Ag nanodots. The cell properties on photoluminescence spectra, quantum efficiency, and conversion efficiency were measured with the maximum values for the sample annealed at 450 degrees C, indicating that there exists an optimal size of the Ag nanodots about 15-35 nm to be effective on the enhancement of surface plasmon effect.