Sputter-Deposited β-Ga₂O₃ Films With Al Top Electrodes for Resistive Random Access Memory Technology*

Gallium oxide $(\beta-\mathrm{Ga}_{2}\mathrm{O}_{3})$ has been considered as a promising candidate for non-volatile resistive switching devices. However, it has been challenging for various deposition techniques to grow crystalline gallium oxide on metal substrates acting as bottom electrode in vertically stacked devices. We studied the synthesis of crystalline $\beta-\mathrm{Ga}_{2}\mathrm{O}_{3}$ on $\mathrm{Ru}/\mathrm{Al}_{2}\mathrm{O}_{3}$ substrates using radio-frequency (RF) magnetron sputtering and characterized the electrical properties of $\mathrm{Al}/\mathrm{Ga}_{2}\mathrm{O}_{3}/\mathrm{Ru}$ devices with respect to the effect of deposition time and temperature. The obtained devices showed more than 70 consistent IV cycles and ON-OFF ratios of up to 10
³
. With increasing temperature and thickness, enhanced stability was observed in the endurance and retention cycles. The resistive switching (RS) behavior in these devices seems to be related to the formation and rupture of oxygen vacancy filaments.