Jang Soohwan, Jung Sunwoo, Baik Kwang Hyeon
Department of Chemical Engineering, Dankook University, Yongin 16890, Korea.
Department of Materials Science and Engineering, Hongik University, Sejong 30016, Korea.
Sensors (Basel). 2020 Feb 4;20(3):835. doi: 10.3390/s20030835.
Enhanced hydrogen sensing performance of Pt Schottky diodes on ZnO single crystal wafers in humid ambient conditions is reported using a polymethylmethacrylate (PMMA) membrane layer. ZnO diode sensors showed little change in forward current when switching to wet ambient H conditions with 100% relative humidity. This sensitivity drop in the presence of water vapor can be attributed to surface coverage of hydroxyl groups on the Pt surface in humid ambient conditions. The hydrogen sensitivity of PMMA-coated diode sensors recovered up to 805% in wet H ambient conditions at room temperature. The PMMA layer can selectively filter water vapor and allow H molecules to pass through the membrane layer. It is clear that the PMMA layer can effectively serve as a moisture barrier because of low water vapor permeability and its hydrophobicity. In both dry and wet conditions, ZnO diodes exhibited relatively fast and stable on/off switching in each cycle with good repeatability.
据报道，使用聚甲基丙烯酸甲酯（PMMA）膜层可提高ZnO单晶晶片上的Pt肖特基二极管在潮湿环境条件下的氢传感性能。当切换到相对湿度为100%的潮湿环境H条件时，ZnO二极管传感器的正向电流变化很小。在有水蒸气存在的情况下这种灵敏度下降可归因于潮湿环境条件下Pt表面羟基的表面覆盖。在室温下的潮湿H环境条件下，涂有PMMA的二极管传感器的氢灵敏度恢复高达805%。PMMA层可以选择性地过滤水蒸气并允许H分子穿过膜层。很明显，由于低水蒸气渗透性及其疏水性，PMMA层可以有效地用作防潮层。在干燥和潮湿条件下，ZnO二极管在每个周期中都表现出相对快速且稳定的开/关切换，具有良好的重复性。
