Controllable Coexistence of Threshold and Non-volatile Crosspoint Memory for Highly Linear Synaptic Device Applications

A highly reliable and versatile resistive memory device that demonstrates threshold and non-volatile (NVM) switching behaviour depending on the compliance current (CC) modulation was utilised by doping a semiconducting (Si) material into a high-k (HfOx) film with highly linear synaptic behaviour. The device shifted towards volatile switching at a CC less than 1 µA and exhibited NVM behaviour at a CC limit above 10 µA. A 3-bit/cell data storage capability on RESET voltage modulation was implemented for high-density memory application. The device exhibited excellent programming linearity of potentiation/depression responses up to 10000 pulses compatible with fast pulse (100 ns) with good ION/IOFF ratio (>10^3), stable data retention capability (10^5 s) at 85°C and high WRITE endurance (~10^7 cycles) with a pulse width of 200 ns. The neuromorphic applications were successfully emulated through neural network simulations using the experimentally calibrated data of the Si-doped HfOx resistive cross-point devices. Simulation results revealed a low nonlinearity of 0.03 with 98.08% pattern recognition accuracy. The estimated results revealed the potential of the device as a low-power selector and high-density NVM storage in large-scale crossbar array in future neuromorphic computing applications.