Effect of Cu, N co-doping on conductive properties of AgSnO2 contact

Abstract

The structure, impurity formation energy, energy band and density of states of SnO2-N,SnO2-Cu and SnO2-Cu-N were studied and analyzed theoretically by using the first- principles method based on the density functional theory in this study. AgSnO2 contacts with different additives were prepared by using sol-gel method and powder metallurgy method, and a series of experiments were carried out on the samples. The simulation results show that the impurity formation energy of Cu,N co-doped SnO2 is the smallest, and its structure is the most stable compared with other doping systems. In the vicinity of Fermi energy level, there is a strong hybridization between Cu atoms and N atoms, and more impurity energy levels are introduced into the forbidden band, which increases the carrier concentration, decreases the band gap and enhances the conductivity. The experimental results show that the doping does not change the structure of SnO2, so the doped SnO2 still belongs to the tetragonal crystal system. And the Cu,N co-doping can greatly improve the wettability between SnO2 and Ag, so that the aggregation of the SnO2 on the contact surface can be effectively prevented, and the contact resistance is reduced. Among the four kinds of AgSnO2, AgSnO2-N, AgSnO2-Cu, AgSnO2-Cu-N contacts, the conductivity of AgSnO2-Cu-N contact is maximum, which is 56.18%IACS, and the contact resistance, arc duration, arc energy and welding force are the smallest, which are 0.946 mΩ, 1.90 ms, 174.31mj and 28.05cN, respectively. Therefore, Cu,N co-doping can fully combine the advantages of Cu single doping and the advantages of N single doping to make up for the shortcomings of AgSnO2 contact, which further improves its conductivity. Moreover, Cu,N co-doping also improves the arc corrosion resistance and anti-welding behaviour of the contact.