The low volumetric energy density of reduced graphene oxide (rGO)-based electrodes limits its application in commercial electrochemical energy storage devices that require high-performance energy storage capacities in small volumes. The volumetric energy density of rGO-based electrode materials is very low due to their low packing density. A supercapacitor with enhanced packing density and high volumetric energy density is fabricated using doped rGO scrolls (GFNSs) as the electrode material. The restacking of rGO sheets is successfully controlled through synthesizing the doped scroll structures while increasing the packing density. The fabricated cell exhibits an ultrahigh volumetric energy density of 49.66 Wh/L with excellent cycling stability (>10 000 cycles). This unique design strategy for the electrode material has significant potential for the future supercapacitors with high volumetric energy densities.

Electroforming-free resistive switching random access memory (RRAM) devices employing magnesium fluoride (MgFx) as the resistive switching layer are reported. The electroforming-free MgFx based RRAM devices exhibit bipolar SET/RESET operational characteristics with an on/off ratio higher than 102 and good data retention of >104 s. The resistive switching mechanism in the Ti/MgFx/Pt devices combines two processes as well as trap-controlled space charge limited conduction (SCLC), which is governed by pre-existing defects of fluoride vacancies in the bulk MgFx layer. In addition, filamentary switching mode at the interface between the MgFx and Ti layers is assisted by O–H group-related defects on the surface of the active layer.

Resistive random-access memory (RRAM) devices are fabricated by utilizing silicon oxynitride (SiOxNy) thin film as a resistive switching layer. A SiOxNy layer is deposited on a p+-Si substrate and capped with a top electrode consisting of Au/Ni. The SiOxNy-based memory device demonstrates bipolar multilevel operation. It can switch interchangeably between all resistance states, including direct SET switching from a high-resistance state (HRS) to an intermediate-resistance state (IRS) or low-resistance state (LRS), direct RESET switching process from LRS to IRS or HRS, and SET/RESET switching from IRS to LRS or HRS by controlling the magnitude of the applied write voltage signal. The device also shows electroforming-free ternary nonvolatile resistive switching characteristics having RHRS/RIRS > 10, RIRS/RLRS > 5, RHRS/RLRS > 103, and retention over 1.8 × 104 s. The resistive switching mechanism in the devices is found to be combinatory processes of hopping conduction by charge trapping/detrapping in the bulk SiOxNy layer and filamentary switching mode at the interface between the SiOxNy and Ni layers.

This study investigates the temperature-independent switching characteristics of magnesium fluoride (MgFx) based bipolar resistive memory devices at temperatures ranging from 300 K down to 77 K.

This study investigates switching characteristics of the magnesium fluoride (MgFx)-based bipolar resistive random-access memory (RRAM) devices at different operating ambiances (open-air and vacuum). Operating ambiances alter the elemental composition of the amorphous MgFx active layer and Ti/MgFx interface region, which affects the overall device performance. The experimental results indicate that filament type resistive switching takes place at the interface of Ti/MgFx and trap-controlled space charge limited conduction (SCLC) mechanisms is dominant in both the low and high resistance states in the bulk MgFx layer. RRAM device performances at different operating ambiances are also altered by MgFx active layer treatments (air exposure and annealing). Devices show the better uniformity, stability, and a higher on/off current ratio in vacuum compared to an open-air environment. The Ti/MgFx/Pt memory devices have great potential for future vacuum electronic applications.