Tunnelling conduction process introduction during the degradation phenomena

M.A. PONCE; M.A. RAMÍREZ; M.S. CASTRO; P.R. BUENO; E. LONGO; J.A. VARELA

Rio de Janeiro

Conferencia; 11th International Conference on Advanced Materials. VII Encontro SBMat; 2009

An adjustment on the electrical degradation phenomena promoted by the application of low dc voltages on SnO2 and ZnO based varistors is presented in this work. The electrical properties of varistors systems were highly damaged after treating the samples. Variations on the potential barrier height and width determined via impedance spectroscopy measurements are discussed on the basis of atomic defects at boundary regions and changes in the donor and surface states densities. Several authors consider thermionic conduction as the dominant process in SnO2 and ZnO varistors but, for an appropriate barriers description, tunnelling current through the barriers must be considered.