Graphene oxide charge blocking layer with high K TiO2 nanowire for improved capacitive memory

Abstract

Glancing angle deposition technique was adopted to fabricate TiO2 nanowire (NW) over spin coated graphene oxide (GO) thin-film (TF) for capacitive memory application. The formation of hybrid structure was studied using field emission scanning electron microscope. High accumulation capacitance of 0.994 nF/cm2 at 7 MHz frequency was obtained for fabricated Au/TiO2 NW/GO TF/Si device as compared to Au/TiO2 NW/Si device (0.4014 nF/cm2). A theoretical study using delta depletion model was done, which further validated the relative permeability and flat band voltage of the devices at higher frequency. The memory window of Au/TiO2 NW/Si was found to be 1.36 V at±10 V, which increased to 3.72 V for Au/TiO2 NW/GO TF/Si hybrid device. Also, a large charge storage capacity with good retention (105 s) and endurance (1000 cycles) was observed for the hybrid device. Moreover, Au/TiO2 NW/GO TF/Si device exhibited low leakage current density of 1.6 µA/cm2 at +1 V as compared to Au/TiO2 NW/Si device (11.3 µA/cm2 at +1 V). The GO TF layer at the bottom increased the potential difference between TiO2 and GO, which acted as a charge trapping layer and thus demonstrated as a good candidate for non-volatile memory application.