Broadband high efficiency silicon nanowire arrays with radial diversity within diamond-like geometrical distribution for photovoltaic applications.

In this study we report novel silicon nanowire (SiNW) array structures that have near-unity absorption spectrum. The design of the new SiNW arrays is based on radial diversity of nanowires with periodic diamond-like array (DLA) structures. Different array structures are studied with a focus on two array structures: limited and broad diversity DLA structures. Numerical electromagnetic modeling is used to study the light-array interaction and to compute the optical properties of SiNW arrays. The proposed arrays show superior performance over other types of SiNW arrays. Significant enhancement of the array absorption is achieved over the entire solar spectrum of interest with significant reduction of the amount of material. The arrays show performance independent of angle of incidence up to 70 degrees, and polarization. The proposed arrays achieved ultimate efficiency as high as 39% with filling fraction as low as 19%.

Design and analysis of a silicon-based terahertz plasmonic switch.

In this paper, a novel terahertz (THz) plasmonic switch is designed and simulated. The device consists of a periodically corrugated n-type doped silicon wafer covered with a metallic layer. Surface plasmon propagation along the structure is controlled by applying a control voltage onto the metal. As will be presented, the applied voltage can effectively alter the width of the depletion layer appeared between the deposited metal and the semiconductor. In this manner, the conductivity of the silicon substrate can be successfully controlled due to the absence of free electrons at the depleted sections. Afterwards, the effectiveness of the proposed plasmonic switch is enhanced by implementing a p(++)-type doped well beneath the metallic indentation edges. Consequently, a P-Intrinsic-N diode is formed which can manipulate the plasmon propagation by modifying the electron and hole densities inside the intrinsic area. The simulation results are explained very concisely by the help of scattering matrix formalism. Such a representation is essential as employing the switches in the design of complex plasmonic systems with many interacting parts.