Photoinduced optical second-harmonic generation of SiNO films deposited on Si〈111〉 substrate

Abstract

Optical photoinduced second-harmonic generation (PISHG) of SiON films deposited on Si〈111〉 substrates has been studied. Nitrogen laser (λ=337 nm) was used as a source of pumping light. We have found that with an increase of photoinducing power and nitrogen-to-oxygen (N/O) ratio, the PISHG for probe YAG-Nd laser (for the doubled frequency λ=0.53 μm) signal increases and achieves its maximum value at photoinducing power about 0.96 GW/cm2. The maximal value of the PISHG was equal about 1 pm/V. With decreasing temperature, the PISHG signal strongly increases below 28 K. Femtosecond probe-pump measurements indicate the existence of the PISHG maximum at pump-probe time delay about 0.4 ps. We explain these dependencies within a framework of the quantum chemical approach and molecular dynamics interface structure optimization. Role of photoinduced anharmonic electron-phonon interaction is demonstrated. We have revealed that Si–N chemical bonds play a key role in the observed photoinduced nonlinear optics effect.