Resistive random-access memory (RRAM) devices are fabricated by utilizing silicon oxynitride (SiO_xN_y) thin film as a resistive switching layer. A SiO_xN_y layer is deposited on a p+-Si substrate and capped with a top electrode consisting of Au/Ni. The SiO_xN_y-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 R_HRS/R_IRS > 10, R_IRS/R_LRS > 5, R_HRS/R_LRS > 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 SiO_xN_y layer and filamentary switching mode at the interface between the SiO_xN_y and Ni layers.

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

The effects of electrode materials (top and bottom) and the operating ambiances (open-air and vacuum) on the MgF_x-based resistive random-access memory (RRAM) devices are studied. Experiment results show that the device’s performance and stability depend on the difference between the top and bottom electrodes’ work functions. Devices are robust in both environments if the work function difference between the bottom and top electrodes is greater than or equal to 0.70 eV. The operating environment-independent device performance depends on the surface roughness of the bottom electrode materials. Reducing the bottom electrodes’ surface roughness will reduce moisture absorption, minimizing the impact of the operating environment. Ti/MgF_x/p⁺-Si memory devices with the minimum surface roughness of the p⁺-Si bottom electrode show operating environment-independent electroforming-free stable resistive switching properties. The stable memory devices show promising data retentions of >10⁴ s in both environments with DC endurance properties of more than 100 cycles.

Electroforming-free resistive switching random access memory (RRAM) devices employing magnesium fluoride (MgF_x) as the resistive switching layer are reported. The electroforming-free MgF_x 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/MgF_x/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 MgF_x layer. In addition, filamentary switching mode at the interface between the MgF_x and Ti layers is assisted by O–H group-related defects on the surface of the active layer.