In this work, an effective bilayer modulation is achieved for the multilayer hexagonal boron nitride (hBN) resistive random-access memory (RRAM) by an insertion of intentionally oxidized titanium oxide layer. The controllable multiple resistance states can be achieved by setting stop voltage of gradual RESET and compliance current during SET, which is beneficial for multilevel storage and neuromorphic application. The switching uniformity and the endurance of memory window are both improved by the effective bilayer modulation. Through experimental data and ab-initio calculation, both the switching and modulation mechanisms are clarified. The effective modulation can be attributed to the multiple thin conductive filaments with dual vacancies within the bilayer stacks of the multilayer hBN and titanium oxide. A significant formation energy difference between the two kinds of vacancy defects existing in bilayer stacks plays the key role for the filament formation through the fixed paths which benefits the switching uniformity. The findings gained from this work can help promote hBN in RRAM application.
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