A plasmonic multilayer structure (PMS) is proposed for photovoltaic cells with an ultrathin active layer that is 30 nm amorphous Si (alpha-Si). The optical properties of the PMS are analyzed by rigorous coupled-wave analysis (RCWA) and finite-difference time-domain (FDTD) method. Using the PMS, the incident light can be trapped into localized surface plasmon (LSP) and then the localized surface plasmon induces the surface plasmon (SP) that propagates transversely within the alpha-Si layer. Compared with the indium tin oxide (ITO)/alpha-Si/Ag structure, the photon number absorbed by PMS increase 28.7% while a normal incident transverse magnetic (TM) polarization wave is applied.
