Yttrium Doping Effects on the Resistive Random Access Memory Characteristics of Sputtered HfO_x Films and Mechanism Investigations

HfO_x-based resistive random-access memory (RRAM) has become a widely studied memory technology due to its simple structure and compatibility with CMOS technology. However, HfO_x-based RRAM exhibits poor performance in terms of endurance and on/off ratio (Appl. Phys. Lett. 2024, 124, 203503; J. Mater. Chem. C 2022, 10, 5896-5904). In this study, the cosputtering technique was used to deposit hafnium oxide films doped with yttrium oxide, aiming to improve the RRAM characteristics of the hafnium oxide films. RRAMs were fabricated with the structure as Pt/HfYO_x/TiN. From the XPS analyses, Yttrium doping helped increase the proposed films’ oxygen vacancy concentration. The device exhibits optimal characteristics at a doping concentration of 0.6% compared to undoped devices. This is evidenced by an increase in endurance from 500 to 2200 cycles, which can be attributed to the SCLC conduction, and an enhancement in the on/off ratio from 23.4 to 382.4, resulting from the rise in oxygen vacancies. In addition, the slope obtained by fitting the current conduction mechanism indicates an increase in the energy barrier between the films after doping. This explains the phenomenon of high-resistance state (HRS) in HfO_x thin film to increase the on/off ratio of proposed films due to Yttrium-doping.