20-nm-Nanogap oxygen gas sensor with solution-processed cerium oxide
20-nm-Nanogap oxygen gas sensor with solution-processed cerium oxide
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DOI：
10.1016/j.snb.2021.130098
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发表时间：
2021-05-12
影响因子：
8.4
通讯作者：
Majima，Yutaka
中科院分区：
文献类型：
--
作者：
Phan，Trong Tue;Tosa，Tsubasa;Majima，Yutaka
采用电子束光刻技术制备了间距为20 nm的pt基纳米间隙电极。这些电极以溶液处理的氧化铈（ceria, CeO2）为传感材料制备纳米间隙气体传感器。采用电解液法和溶液法交替制备了底触和顶触两种类型的纳米间隙气体传感器。研究了氧对间隙间距、氧化铈膜厚度和操作温度的影响。传感器的响应强烈依赖于间隙的分离和氧化铈膜的纳米结构。在35 nm以下的小间隙情况下，在相对较低的573 K工作温度下，纳米间隙气体传感器具有10 s的快速响应时间；在相同的测量条件下，该响应时间比微间隙传感器所显示的响应时间大约短三个数量级。纳米间隙气体传感器也可以在1大气压下使用。传感器性能的提高主要归功于纳米间隙电极的极小间隙分离；减少间隙分离有利于电子在二氧化铈薄膜中跳跃传导。所提出的制造坚固的超细纳米间隙电极的方法以及用于形成传感层的简单涂层方法为开发具有快速响应时间的各种纳米间隙气体传感器开辟了可能性。
Pt-based nanogap electrodes with a gap separation of 20 nm were prepared by electron-beam lithography (EBL). These electrodes were employed to fabricate nanogap gas sensors by combining solution-processed cerium oxide (ceria, CeO2) as the sensing material. Two types (bottom- and top-contact) of nanogap gas sensors were prepared by alternating the EBL and the solution process. Oxygen gas responses were investigated as functions of the gap separation, ceria film thicknesses, and operating temperatures. The sensor response strongly depended on the gap separation and the nanostructure of the cerium oxide film. In the cases of the small gap separation below 35 nm, the nanogap gas sensor exhibits a fast response time of 10 s at a relatively low operating temperature of 573 K; this response time is approximately three orders of magnitude shorter than that exhibited by a microgap sensor under the same measurement conditions. The nanogap gas sensor could also be in use at 1 atm. The improved sensor performance is attributed to the extremely small gap separation of the nanogap electrodes; the reduced gap separation facilitates electron hopping conduction in the ceria film. The proposed approach for fabricating robust and ultrafine nanogap electrodes together with a facile coating method for forming the sensing layer opens up possibilities to develop various nanogap gas sensors with a fast response time.