Temperature-dependent second- and third-order optical nonlinear susceptibilities at the $\text{Si}/{\text{SiO}}_{2}$ interface

Temperature-dependent second- and third-order optical nonlinear susceptibilities at the $Si / {SiO}_{2}$ interface

Xiong Lu, Robert Pasternak, Heungman Park, Jingbo Qi, Norman H. Tolk, Amitabh Chatterjee, Ronald D. Schrimpf, and Daniel M. Fleetwood

Phys. Rev. B 78, 155311 – Published 13 October 2008

Abstract

Using a two-color laser technique, we have measured the temperature dependence of the second- and third-order optical nonlinear susceptibilities, $χ^{(2)}$ and $χ^{(3)}$ , at the $Si / {SiO}_{2}$ interface. A laser beam at 540 nm directed normal to the surface was used to pump electrons from the silicon valence band to trap states on the ${SiO}_{2}$ surface leaving the holes at or near the interface thus creating a capacitance electric field. A second beam of wavelength 800 nm incident at $45 °$ on the same spot resulted in a second-harmonic signal whose intensity was related to the varying interfacial electric field. We find that the photoinduced electric field is temperature independent since the charge distributions remain unchanged after pumping and both $χ^{(2)}$ and $χ^{(3)}$ increase as the temperature increases.