Bipolar resistive switching property of Si3N4−x thin films depending on N deficiency

Abstract

This study investigates the bipolar resistive switching property of a silicon nitride (Si₃N_4−x) thin film deposited by plasma-enhanced chemical vapor deposition using SiH₄ and NH₃ as the Si precursor and N source, respectively, at a wafer temperature of 300 °C. By controlling the NH₃ gas flow rate, the optimized condition for resistive switching behaviors can be achieved. The lowering of the NH₃ reaction gas flow rate induces a N-deficient Si₃N_4−x film, which affects the bipolar resistive switching behavior. Among the various NH₃ gas flow rates, 2 standard cubic centimeters per minute produced Si₃N_4−x films having the optimized switching property with a self-compliance behavior, which could be obtained with the help of the series resistance induced by the parasitic resistance of the Pt top and TiN bottom electrodes. The resistance value of the low-resistance state was independent of the electrode area, suggesting the filamentary resistive switching. The high-resistance state follows the space charge–limited current mechanism. A detailed electrical analysis was performed to identify the trap depth and density for the hopping conduction. Si₃N_4−x is a promising material for feasible resistive switching random access memory.