Design Guidelines for Si(111) Inclined Nanohole Arrays in Thin-Film Solar Cells

In this paper, the slanting silicon nanohole (SiNH) structure is systematically designed and analyzed by simulation using the finite-element method. The slanting angle of the SiNH structure is fixed at 40 degrees based on the Si(1 1 1) wafer. The impact of the SiNH diameter (D) and structural periodicity (P) on the light absorption has been examined. It is found that the absorption is significantly enhanced due to the much suppressed light reflection on the top surface and the strong light trapping ability of the slanting SiNH structure. At the P of 700 nm and D/P ratio of 0.85, the optimal structural parameters are achieved with the highest ultimate efficiency of 32.9%. It is higher than that of the vertical SiNH structure counterpart which has a value of 29.7%. The physical mechanism of the enhanced light absorption is also discussed.