Radiative behaviors of crystalline silicon nanowire and nanohole arrays for photovoltaic applications

•The absorption enhancement of four nanostructure arrays is investigated by RCWA.•An identical optimal lattice constant is found for different nanostructures.•Square nanowire arrays are first studied for their potentials in photovoltaic applications.•It has been found that the efficiency increases when the incident angle is very small.

The optical absorption of four square arrays of crystalline silicon nanostructures, i.e., circular nanowire array, circular nanohole arrays, square nanowire arrays, and square nanohole arrays, are numerically investigated. The method of rigorous coupled-wave analysis (RCWA) is employed to calculate the absorptivity for the arrays with lattice constant from 100 nm to 1500 nm. The results indicated that the lattice constant is the foremost structural parameter to determine the ultimate efficiency, and the peaks of ultimate efficiencies for the four different nanostructures always appear around the lattice constant of 600 nm. It demonstrates that square nanowire arrays and circular nanohole arrays have great potentials for photovoltaic applications with high ultimate efficiencies and low filling ratios. Moreover, high ultimate efficiencies of all structures can be maintained over a large range of incident angles.