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 field-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:Sapphire laser at λ=790 nm, the screening effect results in a nearly parabolic dependence of the SHG efficiency on the potential applied to the electrode in the region of the minimum of the response. Model calculations give good agreement with experimental results.