Enhancing the Resistive Memory Window through Band Gap Tuning in Solid Solution (CrV)O.

Memories based on the insulator-to-metal transition in correlated insulators are promising to overcome the limitations of alternative nonvolatile memory technologies. However, associated performances have been demonstrated so far only on narrow-gap compounds, such as (VCr)O, exhibiting a tight memory window. In the present study, V-substituted CrO compounds (CrV)O have been synthesized and widely investigated in thin films, single crystals, and polycrystalline powders, for the whole range of chemical composition (0 < < 1). Physicochemical, structural, and optical properties of the annealed magnetron-sputtered thin films are in very good agreement with those of polycrystalline powders. Indeed, all compounds exhibit the same crystalline structure with a cell parameter evolution consistent with a solid solution over the whole range of values, as demonstrated by X-ray diffraction and Raman scattering. Moreover, the optical band gap of V-substituted CrO compounds decreases from 3 eV for CrO to 0 eV for VO. In the same way, resistivity is decreased by almost 5 orders of magnitude as the V content is varying from 0 to 1, similarly in thin films and single crystals. Finally, a reversible resistive switching has been observed for thin films of three selected V contents ( = 0.30, 0.70, and 0.95). Resistive switching performed on MIM devices based on a 50 nm thick (CrV)O thin film shows a high endurance of 1000 resistive switching cycles and a memory window / higher by 3 orders of magnitude, as compared to (CrV)O. This comprehensive study demonstrates that a large range of memory windows can be reached by tuning the band gap while varying the V content in the (CrV)O solid solution. It thus confirms the potential of correlated insulators for memory applications.