Impact of Stack Engineering on HfOₓ/Al:HfOₓ-Based Flexible Resistive Memory Devices and Its Synaptic Characteristics

The effect of stack engineering of HfO
_x
/ Al-doped HfO
_x
(Al:HfO
_x
)-based flexible resistive random access memory (ReRAM) devices including its synaptic characteristic has been investigated. The flexible Al/HfO
_x
/Al:HfO
_x
/HfO
_x
/ITO/PET resistive memory device shows outstanding switching performance in terms of repeatability, statistical variation of parameters even in bending condition up to 5 mm. The switching mechanism has been explained by ohmic conduction in low resistance state (LRS) and the trap-controlled space charge limited conduction (SCLC) in high resistance state (HRS). The improved synaptic characteristics, such as long-term potentiation (LTP), long-term depression (LTD), spike-rate-dependent plasticity (SRDP), paired-pulse facilitation (PPF), and post-tetanic potentiation (PTP), are effectively mimicked with Al/HfO
_x
/Al:HfO
_x
/ITO/PET ReRAM, which is suitable for neuromorphic computing application.