Second harmonic generation analysis in hydrogenated amorphous silicon nitride thin films

Surface and interface electronic properties of plasma-deposited hydrogenated amorphous silicon nitride films have been investigated by means of optical second harmonic generation (SHG) technique. Polarization analysis shows that the nonlinear field origins from isotropic interfaces (film/substrate interface and film/air interface) whose spectral features are ascribed to surface/interface Si dangling bonds and strained Si-Si bonds. Differences and similarities with SHG spectra of pure amorphous silicon (a-Si:H) are discussed in terms of compositional inhomogeneities of the ternary alloy.