Amorphous InGaZnO/Poly-Si Coplanar Heterojunction TFT for Memory Applications

We report a heterojunction, nonvolatile memory (NVM) device with amorphous indium-gallium-zinc oxide (a - IGZO) and low-temperature polysilicon (LTPS) stack. The LTPS layer was achieved by blue laser annealing of amorphous silicon. The a - IGZO/LTPS heterojunction NVM exhibits a large threshold voltage (ΔV
_Th
(V)) memory window of 19.2 V with prolonged operational stability. An increase in channel length (L) (from 2 to 20 μm) exhibits a stable memory window. The neutral oxygen vacancy states in a - IGZO trap the carriers at a - IGZO/LTPS interface and then transforms into a metastable state, ( D
^O
+ h
⁺
(2 h
⁺
)→ D
⁺
/ D
⁺⁺
or D
^O
+ e
^-
(2 e
^-
)→ D
^-
/ D
^-
), which is the key to the operation of a - IGZO/LTPS heterojunction NVM.