On the forming-free operation of HfOx based RRAM devices: Experiments and ab initio calculations

We show experimentally that the first reset operation of forming-free HfOx based RRAM devices is of bulk type where the reset current is area dependent. Moreover, the device pristine resistance shows a weak inverse proportionality to temperature, which we associate to a sub-stoichiometric HfOx matrix created during device fabrication. Finally, we use ab initio calculations to gain insight into the atomistic structure of these forming-free RRAM devices.