Self-rectifying effect in gold nanocrystal-embedded zirconium oxide resistive memory

Abstract

The ZrO2 films with Au nanocrystals embedded (ZrO2:nc-Au) are fabricated by e-beam evaporation, and the self-rectifying effect in the Au/ZrO2:nc-Au/n+ Si sandwich structure is investigated. Self-rectifying resistive switching characteristics are obtained when the resistive memory is switched to low-resistance state (LRS). It is found that the Schottky contact at the Au/ZrO2 interface limits charge injection under reverse bias, while under forward bias the current is limited by space charge, resulting in a rectification of 7×102 under ±0.5 V at LRS, which enables the resistive memory to alleviate the cross-talk effect without additional switching elements in crossbar structure arrays. This self-rectifying resistive switching is believed to occur at a localized region and explained by a proposed model.

Electroforming free resistive switching memory in two-dimensional VOx nanosheets

“…This might be due to the existence of electric field dependent thermally generated free carriers at low bias application. 37,38 In region-II (varying from À0.3 to À0.35 V for the temperature range of 300 to 360 K and À0.35 to À0.45 V for 380 K), the current increases rapidly with the applied bias and a certain jump in the current order was found (slope > 2). This may be due to the rapid increase of injected electrons with increasing bias.…”

Memory Select Devices

“…In a RRAM device made from ZrO 2 doped with Au nano-crystals, the low resistance state (LRS) exhibits asymmetrical characteristics with a rectification ratio of 10 2 -10 3 measured at 0.5 V [40]. The self-rectification property is attributed to the Au/ZrO 2 interface, while the resistive switching is explained by the formation of conductive filaments inside of ZrO 2 .…”

Progress in rectifying-based RRAM passive crossbar array

“…There are three necessary requirements for a Zener diode to access a bipolar RRAM: 1) high rectification ratio at a given readout voltage to suppress the unwanted leakage current; 2) proper Zener voltage to obtain a reasonable cell operation voltage; 3) high current density at both positive and negative voltages to guarantee the set and reset resistive switching. Nevertheless, these three basic requirements are difficult to be satisfied simultaneously in one Zener diode to match the performance of RRAM cell, which presents difficulties for the development of 1D1R structure based on bipolar RRAM [17]. Considering the different materials used in the diodes, the types of diodes employed in the 1D1R structure mainly include Si-based diode [18,19], oxide-based diode [16,[20][21][22] and polymer-based diode [23,24].…”

“…Until now the reported RRAM devices with self-rectification are TiW/Ge 2 Sb 2 Te 5 / W [7], Au/ZrO 2 :Au-nanocystal/n + -Si [17], Ag/RbAg 4 I 5 /n-Si [31], Si/a-Si core/Ag nanowires [32], Ag/a-Si/p-Si [33], Pt/ZrO 2 /n + -Si [34] and Ag nanowires/a-Si/poly-Si [35]. Zuo et al [34] manufactured a WORM device using a self-rectifying RRAN device based on Pt/ZrO 2 /n + -Si structure.…”

“…High density is always an important performance pursued by semiconductor industry. As a result, the rectifying RRAM passive crossbar array has received widely attentions and become a very promising method for RRRM Table 2 Partially reported self-rectifying RRAM Structure R HRS / R LRS F / R ratio Endurance Retention TiW/Ge 2 Sb 2 Te 5 /W [7] -->10 3 5000 s Au/ZrO 2 : Au-nanocystal/n + -Si [17] -700@±0.5 V 100 -Ag/RbAg 4 I 5 /n-Si [31] 10 3 @0.2 V -10 3 -Si/-Si core/Ag nanowires [32] 10 4 10 6 @1 V 10 4 >2 weeks Ag/-Si/p-Si(crystalline) [33] 10 3 -10 6 >3 months Pt/ZrO 2 /n + -Si [34] 10 6 @1 V >10 4 -10 5 s Ag nanowires/a-Si/poly-Si [35] >10 6 @0.5 V >10 6 @±0.5 V >10 8 > 4 years to realize high density storage application due to its simple structure, high density, feasibility of 3D stack and so on. It is necessary to further pursue the diodes with high forward current density and high rectification ratio applied in the 1D1R structures.…”