Design of memristor materials from ordered-vacancy zincblende semiconductors

Memristors with promising applications in nonvolatile memory and unconventional computing have attracted much interest for both materials study and device development. Memristors are not commonly realized in zincblende-like semiconductors that could have optimum lattice matching with Si or GaAs substrates in semiconductor technologies, whereas often based on metal oxides with movable oxygen vacancies. Here, we propose the ordered-vacancy zincblende (OVZ) semiconductors as a type of memristor materials. Based on first-principles calculations on the ${\mathrm{Al}}_{2}\text{\ensuremath{-}}X\text{\ensuremath{-}}{Y}_{4}$ group of semiconductors, we select ${\mathrm{Al}}_{2}\mathrm{Cd}{\mathrm{S}}_{4}$ as the best candidate that is lattice matched to Si, with medium energy barriers of \ensuremath{\sim}1 eV for vacancy/ion diffusion, comparable to the metal-oxide memristor materials, suggesting that ${\mathrm{Al}}_{2}\mathrm{Cd}{\mathrm{S}}_{4}$ could be segregated into ion-rich versus vacancy-rich structures via ion drift under electric operation. We find from defect calculations that both ${\mathrm{V}}_{\mathrm{Cd}}$ and ${\mathrm{Cd}}_{i}$ are shallow defects, suggesting a bipolar conduction with electron transport dominated. We further find that the electron-rich ${\mathrm{Al}}_{2}\mathrm{Cd}{\mathrm{S}}_{4}$ structure can be both electrically conductive and optically transparent, showing potential applications as transparent memristors. Our study therefore opens the way of designing OVZ memristor materials with good compatibility with semiconductor technologies, as well as potentially optimum properties for memristor devices.