Exploring the Effects of Mo Doping on Oxygen Vacancy Formation and Uniformity in HfO2- and ZrO2-Based RRAMs

Metal doping plays an important rolein the resistance switchingmechanism of the resistive random access memory (RRAM). The oxygenvacancy (V-O) formation energy under different oxygen partialpressures (P-O2) and temperatures(T), the interaction of Mo dopant with V-O, and the electronic structures of Mo-doped defect systems have beeninvestigated by first-principles calculations. It is found that Modoping significantly reduces the formation energy of neutral V-O and decreases the stability of the +2 charged V-O, especially in the Mo-doped HfO2 system. Lower P-O2 and higher T valuesare more energetically favorable to the formation of V-O. The strong attraction between Mo and V-O with chargestates of 0 and +1q allows more oxygen vacancies to generate aroundthe dopant, indicating that the Mo dopant can effectively modulatethe distribution of V-O, thus improving the uniformity of HfO2- and ZrO2-based RRAMs. The results of theelectronic structures show that Mo doping can significantly enhancethe conductivity of the devices; more electrons will be localizedaround the dopant, V-O, and their surrounding atoms, thuspromoting the formation of conductive filaments (CFs). It can be concludedthat Mo doping can reduce the forming voltage and improve the resistanceswitching performance of HfO2- and ZrO2-basedRRAMs, which provides theoretical guidance for the applications ofmetal-doped HfO2- and ZrO2-based RRAM devices.