Investigation of lithium (Li) doping on the resistive switching property of p-Li:NiO/n-β-Ga2O3 thin-film based heterojunction devices

Abstract

Li-doped NiO/[Formula: see text]-Ga2O3 polycrystalline bilayer thin-film pn-heterojunctions with different Li-doping concentrations are grown on Si-substrates using the pulsed laser deposition technique. Resistive switching property of these devices has been investigated in detail. This study shows that the Li-doping concentration in NiO layer significantly influences the performance of these devices. For an optimum Li-doping of 1.5%, a stable memory window of ∼102 with endurance of more than 100 cycles and long retention time can be achieved. The coefficient of variation ([Formula: see text]) of SET and RESET voltages also found to ∼ 20% and ∼ 40%, respectively, satisfying the acceptability benchmark. A transition from complementary resistive switching (CRS) to bipolar resistive switching (BRS) after multiple sweeping operations has been observed in devices with intermediate Li-doping concentrations. Observation of CRS has been explained in terms of the formation of Li-rich metallic layer at the NiO/Ga2O3 interface as a result of out-diffusion of Li. Redistribution of the Li-ions from the Li-rich interfacial zone to whole of the NiO layer after first few sweeping cycles must be the reason for CRS-to-BRS transition. Results further suggest that return to high resistive state via Poole–Frenkel (PF) pathway during the RESET process might be the key to achieve high performance in p–n junction based resistive switching devices. This study, thus, presents Li-doping as a possible route to modulate the resistive switching property of bilayer Li:NiO/Ga2O3 based memory devices.

Study of lithium incorporation in (111) NiO epitaxial layers grown on c-sapphire substrates using the pulsed laser deposition technique

“…It should be noted that the stoichiometric NiO is an insulator. The p-type conduction in the film can be ascribed to the nickel vacancies (V Ni ) [17][18][19][20]. It is noteworthy that NiO epitaxial films with high crystalline quality have been reported by different growth techniques such as pulsed laser deposition [8,21,22], mist chemical vapor deposition [23], RF magnetron sputtering [24] and molecular beam epitaxy [5] on various substrates, such as sapphire, cubic yttria-stabilized zirconia and MgO.…”