The linear and nonlinear optical response of native‐oxide covered rippled Si templates with nanoscale periodicity

Abstract

AbstractFabrication of dense arrays of nanowires by growth on nanostructured substrates appears to be a promising approach for producing functional nanoscale devices. Ion beam irradiation under carefully controlled conditions produces self‐organized ripple patterns on silicon substrates, on which Ag nanowire arrays with nanoscale periodicity have been grown successfully. Here, the linear and nonlinear optical response from native‐oxide‐covered Si(001) templates, with ripple periodicity between ∼20 and ∼50 nm, is reported. Reflection anisotropy spectroscopy (RAS) shows a small, broad peak at ∼2.5 eV of ∼1 × 10−3 amplitude. The RAS response decreases as the periodicity of the ripple structure increases. The nonlinear second‐harmonic (SH) response from the samples was also measured, using unamplified femtosecond excitation at 800 nm, by rotating the linear polarized input and detecting either the s‐ or p‐polarized SH output. A decrease in response with increased ripple structure periodicity was observed for the p‐in/p‐out configuration, when the plane of incidence was orthogonal to the average ripple orientation. Possible origins of the response and future experiments are discussed.