Nonquadratic second-harmonic generation from semiconductor-oxide interfaces - art. no. 121316

Second harmonic generation on Si1-xGex interfaces shows unusual nonmonotoni c, nonquadratic behavior. This behavior depends strongly on laser wavelengt h and surface termination. It is present for oxide-covered samples at secon d-harmonic wavelengths of 373 nm (3.32 eV), but not at 415 nm (2.99 eV). It is absent at both wavelengths for H-terminated samples. This behavior is c onsistent with photomodulation of an interfacial electric-field-induced con tribution to the second-harmonic response of the system.