Effect of photogenerated carriers on electric field-induced second harmonic generation from Si(001) in an electrochemical cell

Electron-hole pairs produced during optical second harmonic generation (SHG ) at a Si(001) electrode in an electrochemical cell perturb the electric fi eld-induced second harmonic response of the silicon surface. Photogenerated carriers screen the electric field in the space-charge region and enhance the SHG efficiency in the depletion regime. For SHG induced by a Ti:Sapphir e laser at lambda = 790 nm, the screening effect results in a nearly parabo lic dependence of the SHG efficiency on the potential applied to the electr ode in the region of the minimum of the response. Model calculations give g ood agreement with experimental results. (C) 1999 Elsevier Science B.V. All rights reserved.