Optical properties of vertical silicon nanowire arrays withrandom position, diameter, or length

摘要

The optical properties of ordered and disordered vertical silicon nanowire arrays, including random position, diameter, and length, are investigated using the finite-difference time-domain method. The ordered array with diameter of 100 nm shows overall small reflection and large absorption. An absorption peak is located at 2.4 eV, which is due to the optical resonance effect. Both randomly-positioned and random diameter arrays remain unreflective as the ordered array. The absorptance of randomly-positioned nanowire arrays has similar frequency dependence as ordered array, while it is enhanced due to the enhanced scattering. Random diameter array has a different absorptance profile and no evident absorption peak is observed, which is explained by the different resonant frequencies of the inclusion nanowires. Random length can create a random rough top surface on the nanowire arrays, which can reduce reflection and enhance absorption compared to uniform top surface.