Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
Department of Industrial Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
ACS Appl Mater Interfaces. 2017 Jun 14;9(23):19973-19979. doi: 10.1021/acsami.7b03871. Epub 2017 Jun 5.
A trade-off between the carrier concentration and carrier mobility is an inherent problem of traditional transparent conducting oxide (TCO) films. In this study, we demonstrate that the electron concentration of TCO films can be increased without deteriorating the carrier mobility by embedding Ag nanoparticles (NPs) into Al-doped ZnO (AZO) films. An increment of Ag NP content up to 0.7 vol % in the AZO causes the electron concentration rising to 4 × 10 cm. A dependence of the conductivity on temperature suggests that the energy barrier for the electron donation from Ag NPs at room temperature is similar to the Schottky barrier height at the Ag-AZO interface. In spite of an increase in the electron concentration, embedded Ag NPs do not compromise the carrier mobility at room temperature. This is evidence showing that this electron donation mechanism by Ag NPs is different from impurity doping, which produces both electrons and ionized scattering centers. Instead, an increase in the Fermi energy level of the AZO matrix partially neutralizes Al impurities, and the carrier mobility of Ag NP embedded AZO film is slightly increased. The optical transmittance of mixture films with resistivity less than 1 × 10 Ω·cm still maintains above 85% in visible wavelengths. This opens a new paradigm to the design of alternative TCO composite materials which circumvent an inherent problem of the impurity doping.
在传统透明导电氧化物（TCO）薄膜中，载流子浓度和载流子迁移率之间的权衡是一个固有问题。在本研究中，我们通过将银纳米颗粒（Ag NPs）嵌入掺铝氧化锌（AZO）薄膜中，证明了TCO 薄膜的载流子浓度可以在不降低载流子迁移率的情况下提高。在 AZO 中，Ag NP 含量增加到 0.7 体积%，可使电子浓度增加到 4×10^19 cm^-3。导电性随温度的依赖关系表明，Ag NPs 向室温下的电子供体的能垒与 Ag-AZO 界面的肖特基势垒高度相似。尽管电子浓度增加，但嵌入的 Ag NPs 并未降低室温下的载流子迁移率。这证明了 Ag NPs 的这种电子供体机制不同于杂质掺杂，后者会产生电子和离化散射中心。相反，AZO 基质的费米能级升高部分中和了 Al 杂质，Ag NP 嵌入 AZO 薄膜的载流子迁移率略有增加。具有小于 1×10^-3 Ω·cm 的电阻率的混合薄膜的可见光透过率仍保持在 85%以上。这为替代 TCO 复合材料的设计开辟了一个新的范例，避免了杂质掺杂的固有问题。
