Behavior of contact potential difference between gold wire and copper oxide surface by nonlinear distortion method in the process of destroying film

摘要

Nonlinear distortion voltage between gold wire and copper surface is observed. It is known nonlinear characteristics come from electron tunneling through a thin insulation film and electron flow over a Schottkey barrier. The height of nonlinear distortion voltage is changed by copper surface condition. In our study, we examined in the process of destroying copper surface film by DC contact voltage and current. There is a tendency that characteristic of the 2nd order distortion voltages are changed by copper surface film's condition. The 2nd order distortion voltage produces a V type valley by applied DC voltages. The applied DC voltage to minimize the 2nd order distortion voltage is same to "contact potential difference". Therefore a symmetric point of nonlinear characteristic is usually not lay at the origin of V-I characteristic. The contact potential difference changes by copper surface condition, such as oxide film thickness. It is an interesting method to measure contact potential difference while the surface is destroying. It is almost same the characteristics of oxide thickness 50nm and 100nm, but a characteristic of 150nm and 200nm thickness are different from the formers.