Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea.
Nanotechnology. 2010 Apr 23;21(16):165503. doi: 10.1088/0957-4484/21/16/165503. Epub 2010 Mar 26.
We report on a novel method for the fabrication of highly sensitive hydrogen gas sensors based on palladium oxide thin films and have investigated their hydrogen sensing properties and nanostructures. To our knowledge, this is the first report on the use of palladium oxide and reduced palladium thin films as hydrogen sensors. The palladium oxide thin films were deposited on thermally oxidized Si substrates using a reactive direct current (DC) magnetron sputtering system. Considerable changes in the resistance of the palladium oxide thin films were observed when they were initially exposed to hydrogen gas, as a result of the reduction process. After the initial exposure to hydrogen gas of PdO(30%), its sensitivity increased up to approximately 4.5 x 10(3)%. The morphology of the PdO surface was analyzed using a scanning electron microscope (SEM), in order to investigate the interactions between palladium oxide and hydrogen. The SEM images showed a large number of nano-sized cracks on the surface of the palladium oxide during the reduction process, which acted to increase the effective surface-to-volume ratio. The response behaviors of the reduced Pd films to hydrogen gas were reversible and had an enhanced sensing property when compared with those of the pure Pd films. In addition, their sensitivities and response times were improved due to the nano-sized cracks on the surfaces. The results demonstrate that palladium oxide and reduced palladium thin films can be applied for use in highly sensitive hydrogen sensors.
我们报告了一种基于氧化钯薄膜的高灵敏度氢气传感器的新型制造方法，并研究了它们的氢气传感性能和纳米结构。据我们所知，这是首次报道将氧化钯和还原钯薄膜用作氢气传感器。氧化钯薄膜是通过反应直流（DC）磁控溅射系统沉积在热氧化的 Si 衬底上的。当氧化钯薄膜最初暴露于氢气中时，由于还原过程，其电阻发生了相当大的变化。在初始暴露于 30%的氢气后，其灵敏度增加到约 4.5 x 10(3) %。使用扫描电子显微镜（SEM）分析了 PdO 表面的形态，以研究氧化钯与氢气之间的相互作用。SEM 图像显示，在还原过程中，氧化钯表面上出现了大量纳米级裂纹，这增加了有效表面积与体积比。与纯 Pd 薄膜相比，还原 Pd 薄膜对氢气的响应行为具有可逆性和增强的传感性能。此外，由于表面上的纳米级裂纹，其灵敏度和响应时间得到了改善。结果表明，氧化钯和还原钯薄膜可用于高灵敏度氢气传感器。
