Ouyang Jianyong
Department of Materials Science and Engineering, National University of Singapore, Singapore.
Nano Rev. 2010;1. doi: 10.3402/nano.v1i0.5118. Epub 2010 May 26.
Nanometer materials have been attracting strong attention due to their interesting structure and properties. Many important practical applications have been demonstrated for nanometer materials based on their unique properties. This article provides a review on the fabrication, electrical characterization, and memory application of two-terminal resistive-switching devices using nanomaterials as the active components, including metal and semiconductor nanoparticles (NPs), nanotubes, nanowires, and graphenes. There are mainly two types of device architectures for the two-terminal devices with NPs. One has a triple-layer structure with a metal film sandwiched between two organic semiconductor layers, and the other has a single polymer film blended with NPs. These devices can be electrically switched between two states with significant different resistances, i.e. the 'ON' and 'OFF' states. These render the devices important application as two-terminal non-volatile memory devices. The electrical behavior of these devices can be affected by the materials in the active layer and the electrodes. Though the mechanism for the electrical switches has been in argument, it is generally believed that the resistive switches are related to charge storage on the NPs. Resistive switches were also observed on crossbars formed by nanotubes, nanowires, and graphene ribbons. The resistive switches are due to nanoelectromechanical behavior of the materials. The Coulombic interaction of transient charges on the nanomaterials affects the configurable gap of the crossbars, which results into significant change in current through the crossbars. These nanoelectromechanical devices can be used as fast-response and high-density memory devices as well.
纳米材料因其有趣的结构和性质而备受关注。基于其独特的性质，纳米材料已被证明有许多重要的实际应用。本文综述了以纳米材料作为活性成分的两终端电阻开关器件的制备、电学特性和存储应用，这些纳米材料包括金属和半导体纳米颗粒（NPs）、纳米管、纳米线和石墨烯。对于含有NPs的两终端器件，主要有两种器件结构。一种是具有三层结构，金属膜夹在两个有机半导体层之间；另一种是含有NPs的单一聚合物膜。这些器件可以在具有显著不同电阻的两种状态之间进行电切换，即“开”和“关”状态（高阻态和低阻态）。这些特性使这些器件作为两终端非易失性存储器件具有重要应用。这些器件的电学行为会受到活性层和电极中的材料影响。尽管电开关的机制仍存在争议，但一般认为电阻开关与纳米颗粒上的电荷存储有关。在由纳米管、纳米线和石墨烯带形成的交叉点上也观察到了电阻开关。这些电阻开关是由于材料的纳米机电行为。纳米材料上瞬态电荷的库仑相互作用会影响交叉点的可配置间隙，从而导致通过交叉点的电流发生显著变化。这些纳米机电器件也可以用作快速响应和高密度存储器件。
