Depth Gradient Reduced Graphene Oxide Layer via Intense Pulsed Light Annealing Process for the Flexible Resistive Random Access Memory Device

In this study, an intense pulsed light (IPL) is irradiated for reducing graphene oxide (GO) to form a flexible resistive random access memory (ReRAM). The reduced-GO (r-GO) thin semiconductor layer is coated using spin coating method with distilled-water and ethanol-based solution on the flexible bottom electrode (Cu). The irradiation conditions are optimized to obtain high retention and switching characteristics. A top electrode (Al) is formed by deposition process and the electrical characteristics of the ReRAM are measured using a parameter analyzer. The optimally reduced GO-based ReRAM shows write-once read-many times (WORM) characteristics and high electrical performances such as on/off ratio (approximate to 10(3)), operation voltage (-4.2-4.5 V), and excellent retention properties (retention time: 10(8)). The effect of the IPL annealing on GO layer is analyzed using X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). In the analysis results, the depth gradient reduced GO layer is clearly observed. In addition, the switching mechanism of ReRAM is investigated using energy band diagram of ReRAM structure(Cu/GO/r-GO/Al). This ReRAM device fabricated on flexible substrate (PI substrate) does not show the degradation in switching characteristics even after bending the substrate in 1000 times with a 5 mm bending radius, demonstrating excellent mechanical endurance of ReRAM device.

Automated summary

This study demonstrates the use of IPL for reducing GO to form a flexible ReRAM with high electrical performance. Optimizing the irradiation conditions leads to high retention and switching characteristics, with a depth gradient reduced GO layer. The ReRAM shows WORM characteristics, high on/off ratio, long retention time, and excellent mechanical endurance when fabricated on a flexible substrate.