Charge trapping characteristics of sputter-AlO_x/ALD Al₂O₃/Epitaxial-GaAs-based non-volatile memory

In this work, a novel memory capacitor structure has been presented with AlO_x/Al₂O₃ bilayer dielectrics on high mobility Epitaxial-GaAs substrate. We have demonstrated the chemical and electrical properties of metal–electrode/AlO_x/Al₂O₃/epi-GaAs-based memory device in detail. Sputter-grown non-stoichiometric AlO_x has been used for both the charge trapping layer and blocking layer due to its intrinsic charge trapping capability and high bandgap. Ultra-thin tunneling layer of thicknesses 5 nm and 15 nm were prepared by atomic layer deposition technique and memory properties were compared on promising high mobility Epitaxial-GaAs/Ge heterostructure. The proposed device shows excellent charge trapping properties with a maximum memory window of 3.2 V at sweep voltage of ± 5 V, with good endurance and data retention properties. Oxygen-deficient AlO_x layer acted as a charge trapping layer without any additional blocking layer which is impressive for non-volatile memory application on high mobility epi-GaAs substrate. In addition, density Functional Theory (DFT) has been employed to understand the physical origin of the intrinsic charge trapping defects in AlO_x dielectric layer.