The influence of light incidence on the bipolar switching in the two-terminal devices with n-ZnO and p-SrCu2O2 films

The interaction of light with the bipolar characteristics of two-terminal devices synthesized with ZnO film is investigated. Three types of devices are built. The first set consisted of devices with n-ZnO film on SiO2/Si or sapphire substrate. The second set is a vertical p-n junction with n-ZnO film on p-SrCu2O2 film on p-Si substrate. The third set is like the second but with a film of ZnO nanorods placed between the n- and p-layers. The bottom electrode is either a metal film on the Si substrate or the p-Si substrate with low resistance. The top electrode consisted of either a tungsten or Ag coated Au wire tip. The changes in the bipolar characteristics are explained in terms of the control of the mobility of the V-o(++) defects present in ZnO film by the incidence of radiation either from the internal or external source of light. The external source is from the room light or from a lamp. The internal source is from the defect-induced radiation from the p-n junction. The present work illustrates that optical illumination of memristor device with transparent semiconducting oxides modulates the switching characteristics, thus providing an opportunity for improving the number of device states. The results also illustrate that optical modulation of bipolar characteristics is more significant in the p-n junction devices emphasizing the benefits of processing of optoelectronic devices with transparent semiconducting oxides.