Ti–Al–O nanocrystal charge trapping memory cells fabricated by atomic layer deposition

• The charge trapping memory cells were fabricated by atomic layer deposition method.
• The anneal temperature plays a key role in forming nanocrystals.
• The memory cells annealed at 800 °C exhibit better memory performance.
• The band alignment is beneficial to enhance the retention characteristics.

Charge trapping memory cells using Ti–Al–O (TAO) film as charge trapping layer and amorphous Al2O3 as the tunneling and blocking layers were fabricated on Si substrates by atomic layer deposition method. As-deposited TAO films were annealed at 700 °C, 800 °C and 900 °C for 3 min in N2 with a rapid thermal annealing process to form nanocrystals. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the microstructure and band diagram of the heterostructures. The electrical characteristics and charge storage properties of the Al2O3/TAO/Al2O3/Si stack structures were also evaluated. Compared to 700 °C and 900 °C samples, the memory cells annealed at 800 °C exhibit better memory performance with larger memory window of 4.8 V at ± 6 V sweeping, higher program/erase speed and excellent endurance.