The nm-thickness Cu_2-xSe ultrathin film via atomic layer deposition and its memristive effect

The ultrathin film of copper selenide with 50 nm in thickness by the home-made atomic layer deposition apparatus was deposited. Synthesized copper pivalate and bis(triethylsilyl) selenide precursors were used. The deposition rate at 160^oC was 0.48 Å per ALD cycle and the thickness was monitored by the in-situ ellipsometer and further analyzed by an AFM. The composition and structure of the film were found by XPS, Raman and XRD to be Cu_1.16Se. The FTO/Cu_1.16Se/tungsten wire memristor was fabricated and its memristive effect was investigated. The non-linear I - V curve and spike timing dependent plasticity of our Cu_1.16Se memristor demonstrate that short-term potentiation and long-term potentiation occurring in a human brain can be realized by adjusting voltage pulse intervals. A memristor is the electrical equivalent to a synapse. Our memristor shows 1 ms of switching time, 400 s of retention time, R_off/on=2, and the reproducibility over 1000 cycles.