GaN-Based Charge Trapping Memory With an AlN Interfacial Layer for Multi-State Operation

GaN-based tunnel-oxide-free charge trapping memory (CTM) that exploits deep-level interface states and large junction barriers for charge storage has been demonstrated, exhibiting high speed, high endurance, and long retention time. To enhance the data storage capacity, high-density deep-level states at the charge-trapping interface are required. In this letter, we demonstrate the multi-state operation of a GaN-based CTM with an AlN interfacial layer prepared by plasma-enhanced atomic layer deposition (PEALD). The thin PEALD-AlN interfacial layer, positioned between the Al2O3 and the p-GaN channel, increases the memory window (MW) due to the formation of high-density interface states. Post-metallization annealing performed in N2 ambient at <inline-formula> <tex-math notation="LaTeX">$420~^{\circ }$ </tex-math></inline-formula> C improves charge retention, with an extrapolated room-temperature retention time exceeding <inline-formula> <tex-math notation="LaTeX">$10^{{9}}$ </tex-math></inline-formula> s. Based on these, the GaN-based CTM achieves a large MW over 5 V, 2-bit/cell operation, and long-term analog-state storage.