Universal non-polar switching in carbon-doped transition metal oxides (TMOs) and post TMOs

Abstract

Transition metal oxides (TMOs) and post-TMOs (PTMOs), when doped with carbon, show non-volatile current–voltage characteristics, which are both universal and repeatable. We have shown spectroscopic evidence of the introduction of carbon-based impurity states inside the existing larger bandgap effectively creating a smaller bandgap, which we suggest could be a Mott–Hubbard-like correlation effects. Our findings indicate new insights for yet to be understood unipolar and nonpolar resistive switching in the TMOs and PTMOs. We have shown that device switching is not thermal-energy dependent and have developed an electronic-dominated switching model that allows for the extreme temperature operation (from 1.5 to 423 K) and state retention up to 673 K for a 1 h bake. Importantly, we have optimized the technology in an industrial process and demonstrated integrated 1-transistor/1-resistor arrays up to 1 kbit with 47 nm devices on 300 mm wafers for advanced node CMOS-compatible correlated electron random access memory. These devices are shown to operate with 2 ns write pulses and retain the memory states up to 200 °C for 24 h. The collection of attributes shown, including scalability to state-of-the-art dimensions, non-volatile operation to extreme low and high temperatures, fast write, and reduced stochasticity as compared to filamentary memories, such as resistive random-access memories, shows the potential for a highly capable two-terminal back-end-of-line non-volatile memory.