Effects of substrate temperature on resistive switching behavior of planar ZnO resistive random access memories

Resistive switching (RS) characteristics of ZnO films via lateral conducting filaments with a length up to 250 mm were demonstrated. The ZnO films were deposited at a low radio frequency power of 50 W. We controlled the substrate temperature during the sputtering process to modify the crystallinity and oxygen vacancy concentration of the ZnO film. At low substrate temperatures of 25-160 degrees C, the ZnO resistive random access memories (ReRAMs) show high conduction currents and the RS behavior is absent. Optimal temperatures of 240-320 degrees C were found to be suitable for obtaining RS characteristics of the ZnO ReRAMs with electrode distances of 10-250 mm. A much higher temperature of 400 degrees C leads to an extremely low conduction current and the electrical characteristic cannot be measured. Deposition rates, transmittances, energy bandgaps, crystallinities, grain sizes, grain orientations, and distinct RS characteristics of the ZnO films deposited at temperatures of 25-400 degrees C were investigated. The carrier conduction mechanism of the ZnO ReRAM was also studied. (C) 2016 Elsevier B.V. All rights reserved.