论文部分内容阅读
采用基于密度泛函理论的第一性原理对比研究了Cu(111)/HfO2(001),Cu(111)/HfO2(010),Cu(111)/HfO2(100)三种复合材料界面模型的失配率、界面束缚能、电荷密度、电子局域函数以及差分电荷密度.计算结果表明:Cu(111)/HfO2(010)失配率最小,界面束缚能最大,界面体系相对最稳定;对比电荷密度及电子局域函数图显示,只有HfO2(010)方向形成的复合材料体系出现了垂直Cu电极方向完整连通的电子通道,表明电子在此方向上具有局域性、连通性,与阻变存储器(RRAM)器件导通方向一致;差分电荷密度图显示,Cu(111)/HfO2(010)复合材料体系界面处存在电荷密度分布重叠的现象,界面处有电子的相互转移、成键的存在;进一步计算了Cu(111)/HfO2(010)体系距离界面不同位置的间隙Cu原子形成能,表明越靠近界面Cu原子越容易进入HfO2体内,在外加电压下易发生电化学反应,从而导致Cu导电细丝的形成与断裂.研究结果可为RRAM存储器的制备及性能的提高提供理论指导和设计工具.
The first principles of density functional theory (DFT) were used to study the interface models of Cu (111) / HfO2 (001), Cu (111) / HfO2 (010) and Cu (111) / HfO2 The results show that the mismatch rate of Cu (111) / HfO2 (010) is the smallest, the interface binding energy is the largest, and the interface system is the most stable. Comparing The charge density and the electronic local function plot show that only the electron channel in the direction perpendicular to the Cu electrode appears in the composite system formed by the HfO2 (010) direction, indicating that the electrons have localization, connectivity and resistance change in this direction (RRAM) devices are in the same conduction direction. The differential charge density maps show that the charge density distribution overlap at the interface of Cu (111) / HfO2 (010) composite system. The Cu atom formation energies of Cu (111) / HfO2 (010) system at different positions in the interface were further calculated. It indicates that the closer the Cu atom to the interface, the easier it enters the HfO2 body and the electrochemical reaction easily occurs under the applied voltage. Formation and fracture of conductive filaments The results may provide theoretical guidance and tools designed to improve the preparation and performance of the RRAM memory.