Bistable resistive switching in hafnium-silicate thin films

We report on the resistive switching mechanism of dc magnetron sputtered hafnium-silicates (Hf_xSi_1-xO₂) memory thin films. It is observed that the electroforming of these films depends on the thickness and stoichiometry of the insulator as well as on the size of the top electrode (TE). Both high-conducting state (ON) and low-conducting state (OFF) are non-polar and stable. The ratio of resistance of the ON and the OFF state is greater than 10³. Both states, performed by dc voltage sweeping and applying short pulses, are stable over 10⁴s at a read out voltage of 0.2V at 85°C, which are all essential properties for further resistive random access memory (RRAM) applications.