Light absorption engineering of hydrogenated nanocrystalline silicon by femtosecond laser

Abstract

The light absorption coefficient of hydrogenated nanocrystalline silicon has been engineered to have a Gaussian distribution by means of absorption modification using a femtosecond laser. The absorption-modified sample exhibits a significant absorption enhancement of up to ∼700%, and the strong absorption does not depend on the incident light. We propose a model responsible for this interesting behavior. In addition, we present an optical limiter constructed through this absorption engineering method.

Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon

“…Detailed growth conditions can be readily found in our previous works. 14,15 The physical characterizations were measured with x-ray diffraction and highresolution transmission electron microscopy (nanocrystalline size d), Raman spectroscopy (crystalline volume fraction X c ), optical transmission measurements (film thickness L and linear absorption coefficient a 0 ). We exploited a Tauc plot, i.e., (a 0 h) 1/2 versus the photon energy hv to determine the optical bandgap E g .…”