Switching Kinetics Control of W‐Based ReRAM Cells in Transient Operation by Interface Engineering

Abstract

Tungsten (W) is one of the most promising materials to be used in resistive random‐access memory electrodes due to its low work function and compatibility with semiconductors, which raises the possibility of device integration, scalability, and low power consumption. However, W has multiple oxidation states that affect device reliability, due to the formation of semistable oxides at the switching interface. W chemical interaction is modulated through the insertion of Al2O3 or Ti interfacial layers. The time‐dependent switching kinetics are investigated in transient Set/Reset operations. It is observed that a compact and stoichiometric atomic‐layer‐deposited Al2O3 barrier layer completely prevents W oxidation, resulting in a sharp current transient. The use of a sputtered Ti buffer layer allows a partial W oxidation, defining a tunable high‐resistance state by pulse rise time control. Notable improvements in endurance, power consumption, resistance state stabilization, and cycle‐to‐cycle and device‐to‐device variability are reported. Switching kinetics and conductive nanofilament evolution are studied in detail to understand the microscopic effect of the interface modifications. The tunability of multi‐HRS states by pulse timing control in Pt/HfO2/Ti/W is in the interest of network and brain‐inspired computing applications, adding a degree of freedom in the modulation of its resistance.

In‐Memory Computing using Memristor Arrays with Ultrathin 2D PdSeOx/PdSe2 Heterostructure

“…[20,21] Huge randomness similar to the traditional metal-oxide-based memristor is found when amorphous PdSeO x is used as the switching medium (24% and −15.5% for set and reset voltage variations, respectively), as shown in Figure 3a-IV. [8][9][10] The impact of ozone treatment time on the switching behavior is further investigated, as shown in Figure S12 (Supporting Information). It is found that the variations in set and reset voltages are increased with longer treatment after the PdSeO x /PdSe 2 heterostructure is formed, showing a strong dependence on the treatment duration.…”

“…[1] More intriguingly, a significant amount of energy is wasted in transferring the data control of the stochastic filament formation. [9,[17][18][19][20][21][22] However, such double-layered structure usually requires two different oxide materials to be deposited via multistep processing, such as physical sputtering and atomic layer deposition (ALD) at the expense of a thick RS layer, low on/off ratio, and/or large forming voltage. [9,[20][21][22] By far, double-layered RS medium based on oxides has been limited to a thickness above 6 nm, placing a constraint on its scalability limit for further performance enhancement.…”

“…[9,[17][18][19][20][21][22] However, such double-layered structure usually requires two different oxide materials to be deposited via multistep processing, such as physical sputtering and atomic layer deposition (ALD) at the expense of a thick RS layer, low on/off ratio, and/or large forming voltage. [9,[20][21][22] By far, double-layered RS medium based on oxides has been limited to a thickness above 6 nm, placing a constraint on its scalability limit for further performance enhancement. [23] New materials and device concepts are therefore desired to circumvent the switching variability issue and push the scalability limit.…”

“…[5][6][7] Such a twoterminal memristor is typically integrated with metal oxide as a switching medium, which relies on the formation and rupture of filaments in the amorphous medium for resistive switching (RS). [5,6,[8][9][10][11][12] However, the stochasticity of the ions' movement is difficult to control and thus results in poor spatial and temporal variations in the RS performance. [13][14][15] The variation has a significant influence on the computing accuracy loss, as most reported high computing accuracies were only realized with small cycleto-cycle variation.…”

Role of Defects in the Breakdown Phenomenon of Al1–xScxN: From Ferroelectric to Filamentary Resistive Switching

“…When a negative voltage of sufficient magnitude is applied to the TE, the device reaches the LRS because the V N move back toward the active interface, restoring the metal-rich character of the CF at this interface and widening the CF (see Section S1). However, in filamentary VCM devices a much larger window between LRS and HRS is typically experienced. − , The small memory window in the present case could be explained by an extremely narrow gap or by the presence of a significant amount of V N in the gap region in HRS. This could be caused by an insufficiently abrupt I cc for limiting the fast thermal runaway during this process …”