Department of Materials Science & Engineering, National Tsing Hua University, No. 101, Sec. 2, Kuang-Fu Rd, Hsinchu 30013, Taiwan, Republic of China.
Phys Chem Chem Phys. 2012 Oct 5;14(37):13041-5. doi: 10.1039/c2cp41671a.
Single crystalline Sn doped In(2)O(3) (ITO) NWs (nanowires) were synthesized via an Au-catalyzed VLS (vapor-liquid-solid) method at 600 °C. The different sizes (~20, ~40, ~80 nm) of the Au NPs (nanoparticles) provided the controllable diameters for ITO NWs during growth. Phase and microstructures confirmed by high-resolution transmission electron microscope images (HRTEM) and X-ray diffraction (XRD) spectra indicated that the phase of In(2)O(3) NWs had a growth direction of [100]. X-ray photoelectron spectroscopy (XPS) was employed to obtain the chemical compositions of the ITO NWs as well as the ratio of Sn/In and oxygen concentrations. The findings indicated that low resistivity was found for ITO NWs with smaller diameters due to higher concentrations of oxygen vacancies and less incorporation of Sn atoms inside the NWs. The resistivity of NWs increases with increasing diameter due to more Sn atoms being incorporated into the NW and their reduction of the amount of oxygen vacancies. Low resistivity NWs could be achieved again due to excess Sn atoms doped into the large diameter NWs. Therefore, by optimizing the well-controlled growth of the NW diameter and interface states, we are able to tune the electrical properties of Sn-doped ITO NWs.
通过在 600°C 下采用 Au 催化的 VLS（气-液-固）方法合成了单晶 Sn 掺杂 In(2)O(3)（ITO）纳米线（NWs）。不同尺寸（20、40、~80nm）的 Au NPs（纳米颗粒）在生长过程中为 ITO NWs 提供了可控的直径。高分辨率透射电子显微镜图像（HRTEM）和 X 射线衍射（XRD）谱证实的相和微观结构表明，In(2)O(3)NWs 的相具有[100]生长方向。X 射线光电子能谱（XPS）用于获得 ITO NWs 的化学成分以及 Sn/In 比和氧浓度。结果表明，由于氧空位浓度较高且 NW 内部掺入 Sn 原子较少，直径较小的 ITO NWs 的电阻率较低。随着 NW 直径的增大，由于更多的 Sn 原子掺入 NW 并减少了氧空位的数量，NWs 的电阻率增大。由于在大直径 NW 中掺杂了过量的 Sn 原子，因此又可以获得低电阻率 NWs。因此，通过优化 NW 直径和界面态的良好控制生长，我们能够调整 Sn 掺杂 ITO NWs 的电性能。
