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

Abstract

In this work, a novel memory capacitor structure has been presented with AlOx/Al2O3 bilayer dielectrics on high mobility Epitaxial-GaAs substrate. We have demonstrated the chemical and electrical properties of metal-electrode/AlOx/Al2O3/epi-GaAs-based memory device in detail. Sputter-grown non-stoichiometric AlOx 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 AlOx 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 AlOx dielectric layer.