Yang Chia-Ming, Chen Tsung-Cheng, Yang Yu-Cheng, Meyyappan M
Department of Electronic Engineering, Chang-Gung University Taoyuan 333 Taiwan
Institute of Electro-Optical Engineering, Chang Gung University Taoyuan 333 Taiwan.
RSC Adv. 2019 Jul 29;9(40):23343-23351. doi: 10.1039/c9ra01295h. eCollection 2019 Jul 23.
The response and recovery of a graphene-based sensor for nitrogen dioxide (NO) sensing is improved by a combination of two treatments including rapid thermal annealing (RTA) of graphene and UV illumination during the pump down period. A two-dimensional monolayer graphene grown by chemical vapor deposition was transferred to an arc-shape electrode and subsequently heated at temperatures from 200 to 400 °C for 1 min in N atmosphere by RTA to eliminate the chemical residues on the graphene generated in the transfer process. The effect of RTA and poly(methyl methacrylate) (PMMA) residues was investigated using Raman spectroscopy. The shift of the G and 2D bands could be due to graphene suffering from compressive strain and hole doping from the substrate enhanced by the RTA treatment. The hole doping effect was also observed from Hall measurements. Atomic force microscopy images confirm the PMMA residues and surface roughness reduction by the RTA treatment. Annealing at 300 °C enhances the NO sensing response at 1 ppm by 4 times compared to the pristine graphene without RTA. Full recovery of the sensor to the initial baseline could be achieved by the adjustment of UV illumination time.
通过两种处理方法的结合，即石墨烯的快速热退火（RTA）和抽气阶段的紫外线照射，可提高用于二氧化氮（NO）传感的基于石墨烯的传感器的响应和恢复性能。通过化学气相沉积生长的二维单层石墨烯被转移到弧形电极上，随后在氮气气氛中通过RTA在200至400°C的温度下加热1分钟，以消除转移过程中在石墨烯上产生的化学残留物。使用拉曼光谱研究了RTA和聚甲基丙烯酸甲酯（PMMA）残留物的影响。G带和2D带的位移可能是由于石墨烯受到压缩应变以及RTA处理增强了来自基底的空穴掺杂。从霍尔测量中也观察到了空穴掺杂效应。原子力显微镜图像证实了PMMA残留物以及RTA处理导致的表面粗糙度降低。与未经RTA处理的原始石墨烯相比，在300°C退火可使传感器在1 ppm时的NO传感响应提高4倍。通过调整紫外线照射时间，传感器可完全恢复到初始基线。
