Outstanding memory characteristics with atomic layer deposited Ta2O5/Al2O3/TiO2/Al2O3/Ta2O5 nanocomposite structures as the charge trapping layer

•Ta2O5/Al2O3/TiO2/Al2O3/Ta2O5 nanocomposites as charge trapping layer were fabricated by atomic layer deposition.•A large memory window of 10.0 V is achieved at gate voltage of ±10 V.•A high charge trap density of 1.10 × 1013 cm−2 is obtained at ±10 V.•Excellent endurance and better retention properties are confirmed.•The large conduction band offsets between nanocomposites and Al2O3 is beneficial to retention.