We review the results of silicon measurements, which we have performed on suboxide SiO x formed on n and p type Si wafers with different surface textures. Localized vibrational modes through Raman and FTIR, light emission properties by photoluminescence (PL), energy critical points for optical transitions, excited state dynamics and non-linear electrical properties can be used as effective methods in investigating thin oxide layers on Si. Infrared vibrational spectrum of Si-O-Si bondings in terms of transverse-optic (TO) and longitudinal-optic (LO) phonons indicating that disorder induced LO-TO optical mode coupling can be an effective tool in assessing the structural quality of the SiOx. Excited carrier dynamics and switching mechanisms can provide critical information about electronic quality of sub oxides for applications in CMOS circuits.