Transformation of digital to analog switching in TaOx-based memristor device for neuromorphic applications

Abstract

An oxidizable metal diffusion barrier inserted between the active metal electrode and the switching layer decreases the electroforming voltage and enhances the switching stability and synaptic performances in TaOx-based conducting bridge memristor devices. The TiW barrier layer avoids an excessive metal ion diffusion into the switching layer whilst the TiWOx interfacial layer formed between the barrier and switching layer. It modulates the oxygen vacancy distribution at top interface and contributes to the formation and rupture of metal ions-oxygen vacancies hybrid conducting bridge. We observe that the device that relies upon non-hybrid (metal ions only) conducting bridge suffers from the poor analogous performance. Meanwhile, the device made with the barrier layer is capable of 2-bit memory and robust 50 stable epochs. The TaOx also acts as resistance suppressing and thermal enhancement layer, which helps to minimize overshooting current. The enhanced analog device with high linear weight update shows multilevel cell characteristics and stable 50 epochs. To validate the neuromorphic characteristic of the devices, a simulated neural network of 100 synapses is used to recognize 10x10 pixel images.

Oxygen Vacancy Transition in HfOx‐Based Flexible, Robust, and Synaptic Bi‐Layer Memristor for Neuromorphic and Wearable Applications

“…[4] Resistive Random Access Memory (RRAM) or memristor is considered as one of the promising candidate for neuromorphic computing due to its CMOS compatibility, good data endurance, analog resistive switching, and multilevel cell (MLC) characteristics. [5,6] However, achieving analog switching with MLC characteristic and emulating stable synaptic behavior by applying AC pulses are still challenging in RRAM technology. Apart from achieving stable synaptic switching, fabrication of memristors on polymers/plastic is very difficult and crucial in order to minimize cost toward green and wearable electronics.…”

Conductive Bridge Random Access Memory (CBRAM): Challenges and Opportunities for Memory and Neuromorphic Computing Applications

“…Saleem et al demonstrated a transformation of digital switching to analog switching in TaO x -based CBRAM devices by inserting an oxidizable metal diffusion barrier between the AE and switching layer [ 80 ]. The device without an additional barrier layer showed typical abrupt switching behavior ( Figure 12 a,b).…”

“…Reprinted from Ref. [ 80 ]. ( h ) The I–V characteristics of an Ag nanoparticles-doped CNC-based CBRAM device showing analog switching and ( i ) its LTP/LTD characteristics.…”

Practical Approach to Induce Analog Switching Behavior in Memristive Devices: Digital-to-Analog Transformation

“…A diffusion barrier is usually employed in this type of memristor device to control the atomic drift [24,25]. Aftab S. et al used an oxidizable metal TiW as a diffusion barrier layer inserted between the switching layer and active metal top electrode to transform TaOx-based memritor from digital set into analog [26]. Figure 7 shows the I-V curves and synaptic behavior of Cu/TaOx/TiN (device A) and Cu/TiW/TaOx/ TiN (device B) memristors.…”

“…Figure 7.Typical I-V curves and synaptic behavior of devices made without (device A) and with (device B) TiW barrier layer. Reprinted from[26].…”