Investigations of Conduction Mechanisms of the Self-Rectifying n super(+)Si-HfO sub(2)- Ni RRAM Devices

The area, temperature (160-300 K), and bias polarity dependences of the I-V curves of the self-rectifying n super(+)Si-HfO sub(2)- Ni resistance random access memory (RRAM) have been measured systematically. The complementary nonrectifying p super(+)Si-HfO sub(2)- Ni RRAM I-V data are also provided for reference. To explain all experimental data, three resistances in series in the RRAM device: 1) the Si-HfO sub(2) contact resistance R \(_{\mathrm {Si-HfO}}\) ; 2) the HfO sub(2) dielectric resistance R sub(HfO); and 3) the HfO sub(2)- \(Ni\) contact resistance R sub(HfO-Ni) must be considered on an equal footing. Previously reported first principle calculation results for the density of states of the monoclinic HfO sub(2) grain boundary with high and low densities of oxygen vacancy V \(_{O}0}\) are adopted for describing the conductive filament resistance R sub(HfO) of the dielectric at low- and high-resistance states. The temperature dependence of I-V is controlled by three different energy barriers: Schottky-like barrier, multiphonon trap assisted tunneling barrier, and multiphonon deep trap capture barrier (E sub(CAPTURE)). It is demonstrated that all experimental data can be explained in a natural and unified way. This model is valuable not only for understanding the conduction mechanism, but also for guiding the future self-rectifying RRAM technology development.