Effect of Y-doping on switching mechanisms and impedance spectroscopy of HfOx-based RRAM devices.

Y-doping can effectively improve the performance of HfOx-based resistive random-access memory (RRAM) devices, but the underlying physical mechanism of Y doping affecting the performance of HfOx-based memristors is still missing and unclear. Although impedance spectroscopy (IS) has been widely used to investigate impedance characteristics and switching mechanisms of RRAM devices, there is less IS analysis on Y-doped HfOx-based RRAM devices as well as devices at different temperatures. Here, the effect of Y doping on the switching mechanism of HfOx-based RRAM devices with a Ti/HfOx/Pt structure were reported using current-voltage (I-V) characteristics and IS. The results indicated that doping Y into HfOx films could decrease the forming/operate voltage and improve the RS uniform. Both doped and undoped HfOx-based RRAM devices obeyed the oxygen vacancies (Vo) conductive filament model along the grain boundary (GB). Additionally, the GB resistive activation energy of the Y-doped device was inferior to that of the undoped device. It exhibited a shift of the Vo trap level towards the conduction band bottom after Y doping in the HfOx film, which was the main reason for the improved RS performance.