Non-Volatile Field-Effect Transistors Enabled by Oxygen Vacancy-Related Dipoles for Memory and Synapse Applications

Exploring the high-performance non-volatile memories for realizing energy-efficient memory in complementary metal-oxide-semiconductor (CMOS) circuits, memory-in-computing, and the artificial synapse is the key to the rapid growth in data markets. One of the significant aspects is the development of non-volatile field-effect transistor (NVFET), which possesses the advantage of decoupling the “write” and “read” functions using the third terminal. In this work, building on a semiconductor channel integrated with an amorphous Al
₂
O
₃
gate insulator, we report a ferroelectric-like NVFET memory and analog synapse that differ from those utilizing polycrystallinedoped HfO
₂
films. Switchable polarization (P) is demonstrated in TaN/Al
₂
O
₃
/TaN, TaN/Al
₂
O
₃
/Si, and TaN/Al
₂
O
₃
/Ge stacks, which is attributed to the voltage-modulation of the oxygen vacancy and negative charge dipoles in gate insulator. A TaN/Al
₂
O
₃
/Ge capacitor achieves over 10
¹⁰
cycles endurance of polarization-voltage measurement. A memory window (MW) of 0.85 V is obtained in the NVFET integrated with Al
₂
O
₃
insulator under ±3 V at 100 ns program/erase (P/E) condition, and the P/E voltage can be reduced to ±1.6 V. A NVFET analog synapse is demonstrated to have a dynamic range above 100 [asymmetry (|α
_p
- α
_d
|)<; 0.1] with ±2 V/100 ns potentiation/depression pulses. These results can be extended universally to other amorphous oxides and show promise for 3-D (fin-shaped) NVFETs with very small fin pitch.