Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4.
Langmuir. 2010 Mar 16;26(6):4368-76. doi: 10.1021/la903444e.
The glancing angle deposition (GLAD) technique is used to fabricate nanostructured thin films with high surface area. Quantifying this property is important for optimizing GLAD-based device performance. Our group has used high-sensitivity krypton gas adsorption and the complementary technique of cyclic voltammetry to measure surface area as a function of deposition angle, thickness, and morphological characteristics for several metal oxide thin films. In this work, we studied amorphous titanium dioxide (TiO(2)), amorphous silicon dioxide (SiO(2)), and polycrystalline indium tin oxide (ITO) nanostructures with vertical and helical post morphologies over a range of oblique deposition angles from 0 to 86 degrees. Krypton gas sorption isotherms, evaluated using the Brunauer-Emmettt-Teller (BET) method, revealed maximum surface area enhancements of 880 +/- 110, 980 +/- 125, and 210 +/- 30 times the footprint area (equivalently 300 +/- 40, 570 +/- 70, and 50 +/- 6 m(2) g(-1)) for vertical posts TiO(2), SiO(2), and ITO. We also applied the cyclic voltammetry technique to these ITO films and observed the same overall trends as seen with the BET method. In addition, we applied the BET method to the measurement of helical films and found that the surface area trend was shifted with respect to that of vertical post films. This revealed the important influence of the substrate rotation rate and film morphology on surface properties. Finally, we showed that the surface area scales linearly with film thickness, with slopes of 730 +/- 35 to 235 +/- 10 m(2) m(-2) microm(-1) found for titania vertical post films deposited at angles from 70 to 85 degrees. This characterization effort will allow for the optimization of solar, photonic, and sensing devices fabricated from thin metal oxide films using GLAD.
掠角沉积（GLAD）技术用于制造具有高表面积的纳米结构薄膜。定量测量这一特性对于优化基于 GLAD 的器件性能非常重要。我们的团队使用高灵敏度氪气吸附和循环伏安法的互补技术，测量了几种金属氧化物薄膜的沉积角、厚度和形态特征对表面积的影响。在这项工作中，我们研究了具有垂直和螺旋柱形态的非晶二氧化钛（TiO2）、非晶二氧化硅（SiO2）和多晶氧化铟锡（ITO）纳米结构，其斜角沉积范围从 0 到 86 度。使用 Brunauer-Emmett-Teller（BET）方法评估的氪气吸附等温线表明，垂直柱 TiO2、SiO2 和 ITO 的最大表面积增强分别为 880 ± 110、980 ± 125 和 210 ± 30 倍足迹面积（相当于 300 ± 40、570 ± 70 和 50 ± 6 m2 g-1）。我们还将循环伏安法应用于这些 ITO 薄膜，并观察到与 BET 方法相同的总体趋势。此外，我们将 BET 方法应用于螺旋薄膜的测量，发现表面积趋势相对于垂直柱薄膜发生了偏移。这揭示了基底旋转速度和薄膜形态对表面性能的重要影响。最后，我们发现表面积与薄膜厚度呈线性关系，在 70 到 85 度角沉积的 TiO2 垂直柱薄膜中，斜率为 730 ± 35 到 235 ± 10 m2 m-2 μm-1。这项特性评估工作将有助于优化使用 GLAD 制造的薄金属氧化物薄膜太阳能、光子和传感器件。
