Investigation of interface states distribution in metal-oxide-semiconductor structures with very thin oxides by acoustic spectroscopy

Abstract

New technique of acoustic spectroscopy to study interface states in metal-oxide-semiconductor (MOS) structures with a very thin oxide layer based on the acoustoelectric effect resulting from the interaction between the longitudinal acoustic wave and semiconductor-insulator interface is presented. The essential principles and theoretical background of this acoustic spectroscopy technique that can determine the interface states distribution from the measured acoustoelectric response signal as a function of gate voltage (Uac-Ug characteristics) are described. The results obtained on the representative set of MOS structures prepared on both n- and p-type Si substrates by nitric acid oxidation of Si technology and undergone also some thermal treatment demonstrate that the introduced technique of acoustic spectroscopy can be a very useful tool for the interface states characterization.