RRAM Device Characterizations and Modelling
347
2 Physical Mechanism of RRAM
2.1 Resistive Switching Mechanism
Bipolar
The resistive switching of bipolar Ox-RRAM is based on the formation and rupture
of conductive filament (CF) consisting of V O as shown in Fig. 2 [14, 18–20]. The
switching characteristic has strong correlation with the distribution of V O , which will
generate and recombine with oxygen ion (O
2− ) during the resistive switching process.
During SET process, the O
2− at lattice sites will be randomly thermal activated
into the dissociated O
2− under a high electrical field. Meanwhile, a V O leaves at
the lattice sites. The dissociated O
2− will hop to the top electrode (anode) and be
absorbed by the top electrode. The generated V O can assist the electron hopping
from the cathode to anode. So the current will increase and the local electrical field
will be enhanced. Meanwhile, the temperature close to the generated V O sites will
increase. It means the generated V O will accelerate the new generation of V O at the
neighboring sites. Therefore, there is a positive feedback between the V O generation
Fig. 2 Schematic physical process of resistive switching in Ox-RRAM
347
2 Physical Mechanism of RRAM
2.1 Resistive Switching Mechanism
Bipolar
The resistive switching of bipolar Ox-RRAM is based on the formation and rupture
of conductive filament (CF) consisting of V O as shown in Fig. 2 [14, 18–20]. The
switching characteristic has strong correlation with the distribution of V O , which will
generate and recombine with oxygen ion (O
2− ) during the resistive switching process.
During SET process, the O
2− at lattice sites will be randomly thermal activated
into the dissociated O
2− under a high electrical field. Meanwhile, a V O leaves at
the lattice sites. The dissociated O
2− will hop to the top electrode (anode) and be
absorbed by the top electrode. The generated V O can assist the electron hopping
from the cathode to anode. So the current will increase and the local electrical field
will be enhanced. Meanwhile, the temperature close to the generated V O sites will
increase. It means the generated V O will accelerate the new generation of V O at the
neighboring sites. Therefore, there is a positive feedback between the V O generation
Fig. 2 Schematic physical process of resistive switching in Ox-RRAM