Temperature- and pulse-dependent negative differential resistances in ZnO/Nb:SrTiO3 heterojunctions.

Temperature- and pulse amplitude/width dependent current-voltage characteristics were performed to study the variance of negative differential resistance (NDR) features accompanying bipolar resistive switching. Interestingly, the absolute value of the NDR peak intensity is enhanced at first and then weakened, while the NDR peak position gradually shifts toward the lower absolute bias value with an increase in temperature from 140 to 300 K, and shifts toward the larger absolute bias value with an increase in temperature from 300 to 400 K. Furthermore, the NDR peak is absent after applying a small and narrow positive pulse, while it gradually increases with increasing the applied pulse amplitude or width. These temperature- and pulse-dependent NDR behaviors can be fully understood based on a model of generation and drift of ionized oxygen vacancies coupled with trapping/detrapping electrons. The clarification of the mechanism will pave the way for practical applications. [ABSTRACT FROM AUTHOR]