Effects of different dopants on switching behavior of HfO₂-based resistive random access memory

In this study the effects of doping atoms (Al, Cu, and N) with different electro-negativities and ionic radii on resistive switching of HfO₂-based resistive random access memory (RRAM) are systematically investigated. The results show that forming voltages and set voltages of Al/Cu-doped devices are reduced. Among all devices, Cu-doped device shows the narrowest device-to-device distributions of set voltage and low resistance. The effects of different dopants on switching behavior are explained with deferent types of CFs formed in HfO₂ depending on dopants: oxygen vacancy (Vo) filaments for Al-doped HfO₂ devices, hybrid filaments composed of oxygen vacancies and Cu atoms for Cu-doped HfO₂ devices, and nitrogen/oxygen vacancy filaments for N-doped HfO₂ devices. The results suggest that a metal dopant with a larger electro-negativity than host metal atom offers the best comprehensive performance.