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/ SiO2 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 SiO2 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. © 2008 The American Physical Society.