Improvement of capacitive and resistive memory in WO₃ thin film with annealing

In this study, electron beam evaporated tungsten oxide (WO₃) thin film (TF) has been investigated for both capacitive and resistive switching memory devices. The fabricated samples underwent annealing at a temperature of 500 °C. Capacitance–voltage (C–V) and conductance–voltage were found to decrease with the increase in frequency for both the as-depo and annealed Au/WO₃ TF/Si devices. The decrease in the interface trap density (D_it) from 1.27 × 10¹¹ eV⁻¹ cm⁻² (as-depo WO₃ TF) to 1.81 × 10¹⁰ eV⁻¹ cm⁻² (annealed WO₃ TF) was attributed to the reduced number of defects. A large memory window of 9.76 V at ± 10 V was exhibited for annealed WO₃ TF in the C–V hysteresis loop. A stable high resistance state and low resistance state were obtained for the annealed device up to 10⁵ s without any distinct deterioration. The effects of crystallization are comprehensively explored to explicate the alteration in the resistive switching characteristics and its fundamental mechanism. The observed alterations in resistive switching behavior have been attributed to the processes of charge-trapping de-trapping and the migration of oxygen vacancies within the film. Our work offers insights into the charge-trapping mechanisms in WO₃ TF-based nonvolatile memory devices, highlighting the impact of annealing on their performance.