Resistive and New Optical Switching Memory Characteristics Using Thermally Grown Ge_0.2Se_0.8 Film in Cu/GeSe_x/W Structure

It is known that conductive-bridge resistive-random-access-memory (CBRAM) device is very important for future high-density nonvolatile memory as well as logic application. Even though the CBRAM devices using different materials, structures, and switching performance have been reported in Nanoscale Res. Lett., 2015, however, optical switching characteristics by using thermally grown Ge_0.2Se_0.8 film in Cu/GeSe_x/W structure are reported for the first time in this study. The Cu/GeSe_x/W memory devices have low current compliances (CCs) ranging from 1 nA to 500 μA with low voltage of ±1.2 V, high resistance ratio of approximately 10³, stable endurance of >200 cycles, and good data retention of >7 × 10³ s at 85 °C. Multi-steps of RESET phenomena and evolution of Cu filaments’ shape under CCs ranging from 1 nA to 500 μA have been discussed. Under external white-light illumination with an intensity of 2.68 mW/cm² (wavelength ranges from 390 to 700 nm), memory device shows optical switching with long read pulse endurance of >10⁵ cycles. This CBRAM device has optically programmed and electrically erased, which can open up a new area of research field for future application.