dc-Electric-field-induced and Low-frequency Electromodulation Second-harmonic Generation Spectroscope

Summary form given. The second-harmonic generation (SHG) has been one of the most intensively studied phenomena in surface and interface optics for the last decade due to its unique sensitivity to the structural and electronic properties of surfaces and interfaces of centrosymmetric media. A dc electric field breaks the inversion symmetry of the centrosymmetric semiconductor in the space-charge region (SCR) and induces the bulk dipole nonlinear polarization at the SHG frequency, which is governed by the cubic susceptibility.