Influence of DC bias on nonlinear distortion of contacts

Abstract

AbstractWhen the nonlinear distortion generated at the metal contact is measured by the two‐frequency method, spectroscopic measured results ranging from the second‐ to sixth‐order distortions can be obtained. Depending on the type of contact and the contact condition, the characteristics of these distortion spectra are different. It was reported previously, together with the measurement technique, that this measurement can be used as a measure for finding the physical phenomena on the contact surface. In the present study, the second‐ and third‐order distortions are considered to be representatives of the even‐ and odd‐order distortions for the purpose of finding the cause of the distortion. A dc bias is applied to the contact and the bias dependence of the distortion voltage is studied. As a result, it is found in most contacts that the second‐order distortion voltage is affected strongly and becomes a minimum at a certain bias point. This indicates that at this bias point the diode characteristics which are the cause of the even‐order distortion vanish and the nonlinearity is almost perfectly symmetric for the currents in both directions. Especially, in this measurement, the bias dependence is observed even if glossy metals are contacted. Hence, this is a method for finding the surface phenomena for a thin‐film thickness from the electrical characteristics.