Electroforming-Free, Flexible, and Reliable Resistive Random-Access Memory Based on an Ultrathin TaO_x Film

Abstract

A flexible resistive switching (RS) memory was fabricated on a Ta/TaO x /Pt/polyimide (PI) structure with various TaO x thicknesses (5, 10, and 15 nm). The oxygen vacancy (V O ) concentrations in the TaO x films were also adjusted by controlling the oxygen partial pressure during TaO x deposition to obtain different electroforming (EF) behaviors. When the devices of Ta/TaO x / Pt/PI showed the EF-free characteristic, the reliability and endurance performance were greatly improved compared to those of devices with EF behavior. The resistive crossbar array using the thinnest (5 nm) TaO x film showed high uniformity and endurance performance up to 10 8 switching cycles even after bending to a 2 mm radius 10 000 times. However, for the EF samples, the endurance performance was much lower and involved the reset failure, even with the 5 nm TaO x film.

Structural Analysis and Performance in a Dual‐Mechanism Conductive Filament Memristor

“…Previous study reported that the resistance of the device showed dependence on the device size. [22,40] The resistance of device decreased as the device size decreased, which is consistent to our measurement in Figure S5a, Supporting Information. In addition, smaller memory window (R OFF /R ON ) of bigger device was observed under similar filament condition (Figure S5b, Supporting Information).…”

“…The results in Figure S4c,e, Supporting Information, agreed with Figure 1b, indicating the consistent distribution of oxygen vacancies. [22,38] From the peak deconvolution of XPS spectra in Figure S4d-f, Supporting Information, it was found that the Ta 2 O 5 contained considerable amounts of oxygen defects, partial lattice oxygen, and surface absorbed oxygen.…”

“…With the existence and elimination of the intrinsic oxygen vacancies in Ta 2 O 5 , a RRAM device with Ta 2 O 5−x could perform as a VCM device. [22,23] Moreover, copper has been studied as the active electrode for ECM devices due to its high diffusion coefficient in Ta 2 O 5 . [24] By applying copper as the top electrode, the device could not only exhibit the electrical properties of ECM but also improve the compatibility between RRAM devices and interconnects in integrated circuits for further applications.…”

A dual-functional Ta/TaOx/Ru device with both nonlinear selector and resistive switching behaviors

“…2(d), nearly 10 3 NL (V read ¼ 1.5 V, 1/2V read ¼ 0.75 V) can be achieved in the integrated 1S1R cell, which signicantly reduced half-selected cells' leakage current. 27,33 Fig. 1 Besides the non-linear selection, our device also shows uniform resistive switching characteristics.…”

“…The memristors based on Ta/TaO x system shows excellent electrical characteristics, such as high endurance (more than 10 11 ), fast speed (10 ns), low switching energy (sub 110 nJ), analogue switching. [25][26][27][28] And the non-linear selector devices based on TaO x have been reported before. [29][30][31] However, a single device based on Ta/TaO x system with coexistence of stable resistive switching and uniform non-linear selection has not yet been reported and a clear physical explanation of this mechanism is still lacking.…”