Nonlinear characteristics of electrical insulating films with nm thickness sandwiched between Au-Au contact

The existence of electrically resistive film layers formed on contact surfaces increases contact resistance and causes a nonlinear relationship between voltage and current observed in a contact layer. Nonlinear distortions of voltage can be detected by a sensitive nonlinearity detection system based on the dual frequency method when a thin film exists on the surface. The relationship between film thickness and electrical properties of the film is explored, and the film thickness is determined using the nonlinearity detection system. Multilayer films of polyimide (PI) are formed on gold evaporated on a glass substrate on a gold plate, and on a gold evaporated gold plate. A pin contact is made by pressing a bended gold wire on the PI film. It is concluded that the second-order distortion voltage increases exponentially as the film thickness increases, polarity of the surface potential of PI depends on the film thickness, and that the I-V characteristic depends on the polarity of the surface potential