Studies on nonvolatile resistance memory switching in ZnO thin films

Abstract

Six decades of research on ZnO has recently sprouted a new branch in the domain of resistive random access memories. Highly resistive and c-axis oriented ZnO thin films were grown by us using d.c. discharge assisted pulsed laser deposition on Pt/Ti/SiO 2 /Si substrates at room temperature. The resistive switching characteristics of these films were studied in the top-bottom configuration using current-voltage measurements at room temperature. Reliable and repeated switching of the resistance of ZnO thin films was obtained between two well defined states of high and low resistance with a narrow dispersion and small switching voltages. Resistance ratios of the high resistance state to low resistance state were found to be in the range of 2-5 orders of magnitude up to 20 test cycles. The conduction mechanism was found to be dominated by the Ohmic behaviour in low resistance states, while Poole-Frenkel emission was found to dominate in high resistance state. The achieved characteristics of the resistive switching in ZnO thin films seem to be promising for nonvolatile memory applications.

Flexible and transparent ReRAM with GZO memory layer and GZO-electrodes on large PEN sheet

“…Note that the reset switching in Fig. 9 is smooth and continuous in contrast to that observed in pure ZnO [1,[16][17][18], which is sharp and discontinuous. This enables voltage pulse control of the resistance.…”

Switching characteristics of ZnO based transparent resistive random access memory devices grown by pulsed laser deposition

“…3rd harmonic of a Q-switched Nd: YAG laser (355 nm, 10 Hz and 6 ns) at a laser fluence of 0.6 J/cm 2 was used for ablation. The details of the growth method can be found elsewhere [6]. About ~250 nm thick film of 0.75 at% Ga doped ZnO with resistivity ~ 1x10 -4 ohm-cm grown using PLD at a substrate temperature of 500 o C was used as bottom electrode.…”

“…Article tom electrode, about 90 nm thick high resistive ZnO film was grown by using a DC-discharge assisted PLD in oxygen ambient [6]. The transparent conducting electrodes of circular shape of Ga (~0.75 at%) doped ZnO films having thickness of ~180 nm and diameter ~300 μm were deposited using PLD over the high resistive ZnO layer using mask.…”

A Novel Approach to use Nano-Sensor in WSN Applications

“…Here the Combined Sensing unit has both sensing units for molecule level sensing and for environmental sensing of a wireless sensor name as NSU and SU respectively, these two units are able to communicate between each other or separately with the processing unit when needed. Inside NSU we may use the ZnO (thinfilm, Nanobased) according to Kukreja et al [28] memory unit because ZnO has the large Excitation energy (60 MeV) , hard material and high temperature operable. Reliable and repeated switching of the resistance of ZnO thin film was obtained between two well defined states of high and low resistance with a narrow dispersion and small switching voltage.…”