Introduction
Resistance switching phenomena, observed in simple metal-insulator-metal stacks so-called resistance random access memory (RRAM) is attracting everyone's attention in the field of non-volatile memory technology due to possible alternative candidate for next generation memory technology [1]–[2]. Although various materials have been reported for resistive switching, binary oxides have advantage over other resistive switching materials in terms of simple composition and easy fabrication process. Among other binary oxides such as TiOx, [3]–[5] NiO, [6]–[7] HfOx, [8]–[10] ZrOx, [11]–[12] AlOx, [13]–[14] etc., tantalum oxide [15]–[18] is one of the promising choices due to its thermal stability and complementary metal oxide semiconductor (CMOS) compatibility as it is being used in the dynamic random access memories in the current semiconductor industry. Moreover, TaOx based resistive memory devices have shown good memory performance reported in various studies [19]–[20]. However, formation-free operation, resistance ratio (HRS/LRS), low power consumption, switching uniformity and device yield are important parameters. In this study, formation-free resistive switching properties of W/TaOx/TiOxN/TiN memory device fully fabricated at room temperature has been investigated and compared with W/TaOx/W structure. The memory device with TiN bottom electrode (BE) has shown improved resistive switching with small set/reset voltage of <1.5 V and resistance ratio of >30 at a small current compliance of as compared to W BE device. The improvement is due to the formation of an oxygen deficient interfacial layer of TiOxN between TaOx and TiN BE which controls oxygen vacancy defects. The switching mechanism is attributed to the formation/dissolution of oxygen vacancy filament due to the migration of oxygen ions when voltage is applied on TE. Good read endurance of times and data retention at 85 °C are also obtained.