Resistive switches in Ta2O5-α/TaO2−x Bilayer and Ta2O5-α/TaO2−x/TaO2−y Tri-layer Structures

Enough R
_off
/R
_on
ratio is important for RRAM application. In this study, a Ta
₂
O
_5-α
/TaO
_y
/TaO
_x
tri-layer structure device was fabricated by reactive sputtering and plasma oxidation and a Ta
₂
O
_5-α
/TaO
_x
bi-layer structure device was also fabricated for comparison. Resistive switching characteristics of both types of devices were investigated under different compliance current. Both types of devices revealed nearly the same reset current which was as low as ~40 μA. The R
_off
/R
_on
ratio of the tri-layer structure devices was increased from 2 to more than 20 by inserting a TaO
_y
layer. The memory windows of the bi-layer structure devices increased to 3 while the memory windows of the tri-layer structure devices decreased to 8 when the compliance current increased from 40 μA to 60 μA. The stability of the tri-layer structure devices became worse under larger compliance current. The results indicate that that inserting a TaO
_y
is beneficial for the memory windows of devices and a smaller compliance current is more suitable for the tri-layer structure devices.