| 초록 |
We have developed a novel and artificially controllable strategy of an electrodeposition process adequate for resistive random-access memory (ReRAM) applications of binary cuprous oxides (Cu2O). Typically, the OH- in the electrolytes serves as the intermediate supplier of oxygen ions for the Cu2O products, and the precise control of OH- ion concentration at the electrode’s surface decides the overall reaction rate. Here, we found that the selected Pb and Sb metal additives preferentially contribute to the consumption of OH- ions and the supply of OH- ions, respectively, during the Cu2O electrochemical reaction so that the final products from only a small amount of Sb and Pb precursors are the (200) preferential quadrangular pyramids and the (111) preferential triangular pyramids. Interestingly, the coexistence of Sb and Pb precursors in the Cu electrolytes results in extraordinarily decreased reaction rate from the opposite action of OH- ion utilization as well as intense progressive growth behavior, and the resultant Cu2O films consist of crystallized small-size nanoparticles (NPs) (5–10 nm) in the amorphous-like matrix. In the case of ReRAM applications, while the polycrystalline film induces irregular device performance and amorphous metal oxide shows the easily irreparable electrical breakdown, our NPs-embedded Cu2O films from Pb/Sb metal precursors reveal the formation of a cushy conduction bridge via phase change from dense NPs to crystalline filament with no need for forming voltage and with superior electrical stability. The formation of conducting bridge is attributed to the coalescence of crystal NPs into large grains during the set/reset cycle process for the heat dissipation of Joule heating. The Cu2O sample prepared with the 3 mM Sb + 3 mM Pb mixture solution exhibits forming-free ReRAM devices with high on/off resistance ratios of 1.2 × 104 and very stable from long-term electrical and thermal stress |
