Highlighting the Au/TiO2 role in the memory effect of Au/TiO2/ITO/ZnO:Al/p-Si heterostructure

We report an electrical investigation on the Au/TiO2/ITO/ZnO:Al/p-Si heterostructure, presenting a resistive switching (RS) behavior. The corresponding net variation of the electrical resistance between the high resistive and the low resistive paths reaches 180 and 140 Ω, respectively, in dark and under illumination. This proves that the RS can be optically modulated. The temperature dependence of the conductance (G–T) illustrates an obvious conductance loss (ΔG) that takes place at low temperatures. This ΔG is attributed to the capture of the injected carriers through the Au/TiO2 junction and it is directly depending on the signal frequency. G–T plots exhibit a transition behavior which requires threshold activation energy. The conductance evolution is correlated to the frequency dependence of the capacitance of the structure. By annealing the structure in an oxygen atmosphere, we found that the ΔG disappears for all investigated frequencies and therefore the RS too. Thus the RS phenomenon takes place in the TiO2 layer involving oxygen vacancies as trapping centers. This result predicted by many works is promising to improve the efficiency of several electronic components used for the electrical memory effect.