Enhanced endurance reliability and low current operation for AlOx/HfOx based unipolar RRAM with Ni electrode

• A thin inserted AlOx layer were used to suppress soft error in HfOx RRAM.
• The Ni/AlOx/HfOx devices show a robust endurance and retention.
• The Ni/AlOx/HfOx devices show higher on/off ration and set voltage.
• A plausible mechanism of AlOx in the HfO device with Ni is discussed.
• The Ni/AlOx/HfOx devices show a feasibility of low current operation.

A 1-nm-thick AlOx layer is adopted to successfully eliminate soft-errors and reduce the operation current in HfOx based unipolar resistive random access memory (RRAM) with Ni as top electrode. Ni/HfOx/TiN RRAMs with one transistor–one resistor configuration during repetitive programming/erasing suffer serious soft-errors. The AlOx layer can share the applied voltage and suppress the soft-errors in the AlOx/HfOx based RRAM in high resistance state. The AlOx layer also modifies the conductive filaments in the devices with the low resistance to avoid the unexpected resistive switching. The forming/SET voltage, the high resistance state, and the on/off ratio in the Ni/AlOx RRAMs are larger than those of Ni ones. In particular, the soft-errors in the devices with ramped voltage verification are eliminated. The intermediate AlOx film is also beneficial for the reduced operation current of the device, which is as low as 10 μA with a pulse width of 40 ns.