Bonding and electronic structures of amorphous SiNx:H

The bonding properties and annealing effects for glow-discharge amorphous silicon nitride (GD a-SiNx:H; x=0–0.33) have been investigated by means of x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and optical measurements. After annealing, a fraction of the N atoms were effused from the film. Shifts of the XPS spectra (Si2p and N1s lines) toward higher binding energy with x are observed. The opposite and large shifts are also observed in the AES spectra (SiLVV and NKLL lines). The peak binding energy EB(Si2p) of the Si2p is connected with a weighted average coordination number nav at a Si site in the SiNn (n=0,...,4) configurations, and the chemical shift per Si–N bond in the Si2p core level is 0.7 eV. For EB(Si2p) and the peak kinetic energy EK(SiLVV), a linear reduction in (EB+EK) with x is found. This result implies that the approach of the N atoms to the Si–Si bonds serves to shift the Si3p native bonding states downward. This model is consistent with the changes of the optical gap and slope B in the Tauc equation as a function of x. A reduction in EB(N1s)+EK(NKLL) with x is also found, indicating that the shifts of the N1s and NKLL are chemical shifts.