Inelastic electron tunneling spectra of Al/Al-oxide/SiO/Pb

Inelastic electron tunneling spectroscopy (IETS) is used to investigate the vibrational modes of planar magnetron radio-frequency sputter deposited ultrathin SiO incorporated in Al/Al-oxide/SiO/Pb tunnel junctions. Films of Al-oxide are formed by exposure of a thin film aluminum base electrode to an oxygen glow discharge. Vibrational modes associated with SiH and Si-O-Si are observed in the spectra. Comparison of forward and reverse bias spectra shows that the SiH species are located on the SiO surface. The SiH species may be removed by exposure of this surface to an argon glow discharge. Spectra obtained from SiO films of thickness, in the range, 0.5 to 2.5nm shows that as the film thickness increases the observed Si-O-Si and SiH vibrational mode intensities increase proportionally