Small amounts of In2O3 and Li2O were added to the ZnO‐Bi2O3‐MnO2 ternary primitive varistor system. Considering Schottky disorder and Frenkel disorder, oxygen vacancy or zinc interstitial density was expected to decrease with In2O3 doping and to increase with Li2O doping. Using admittance spectroscopy, a 0.32eV electron trap, which was suggested to be an ionized oxygen vacancy, was observed regardless of the doping conditions. Changes in the peak height, for the 0.32eV trap, in the admittance spectra were correlated with In2O3 and Li2O doping. Doping with In2O3 reduced the conductance contribution due to the trap, while doping with Li2O enhanced it. However, calculations showed that small amounts of dopants, less than 100ppm, do not greatly influence the trap density. The trap density remains within experimental error approximately 1.0 x 1017/cm3.

Effects of Dopants on the Deep Bulk Levels in the ZnO‐Bi2O3‐MnO2 System. Shim, Y., Cordaro, J.F.: Journal of Applied Physics, 1988, 64[8], 3994