Investigation of deep level transient spectroscopy (DLTS) of dopant ZnO-based varistors

This work shows that the use of conventional analytical procedures to investigate the deep centers from the deep levels transient spectroscopy (DLTS) for ZnO varistors doped with single, double and ternary dopants of Bi2O3, CoO and MnO2. This is to clarify the effect of these doping atoms on the conductivity of ZnO varistors. The results showed that the doping with Bi2O3 +CoO leads to a decrease in the conductivity while doping with Bi2O3+MnO2 increased the conductivity and the three dopants together showed a compensating effect. The DLTS characterizing parameters such as minority-carrier capture cross-section, σ, effective density of states in the minority-carrier band, ND, energy separation between the trap level and the minority-carrier band, ΔEt and electron trap density, Nt for each doped varistor were also calculated.