Effects of surface morphology randomness on optical properties of Si-based photonic nanostructures

We have fabricated Si-based photonic nanostructures with submicron sizes by the maskless wet etching of Ge quantum dot (QD) multilayers and demonstrated that the photonic nanostructures result in the enhanced optical absorption in the near-infrared light owing to light trapping. In this study, the optical properties of Si-based photonic nanostructures with surface morphology randomness were calculated by the finite-difference time-domain (FDTD) method. The obtained results indicate that as the degree of randomness increased, the absorption in a near-infrared light range enhanced, suggesting that the enhancement of optical absorption in the near-infrared light by photonic nanostructures is due to the randomness of the nanostructures.