Functionalization of GaN Nanowire Sensors With Metal Oxides: An Experimental and DFT Investigation
Functionalization of GaN Nanowire Sensors With Metal Oxides: An Experimental and DFT Investigation
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DOI：
10.1109/jsen.2020.2978221
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发表时间：
2020-07-01
影响因子：
4.3
通讯作者：
Rao, Mulpuri, V
中科院分区：
文献类型：
--
作者：
Khan, Md Ashfaque Hossain;Thomson, Brian;Rao, Mulpuri, V
本文基于密度泛函理论（DFT）的第一性原理计算，对各种金属氧化物功能化的氮化镓纳米线传感器对NO2分子的检测进行了全面的研究。在本研究中，采用标准的自顶向下制造工艺在Si衬底上制备GaN纳米线，然后制成基于电阻的化学传感器。采用TiO2、ZnO和SnO2三种金属氧化物对GaN纳米线表面进行了功能化处理。紫外照明器件表征结果表明，TiO2功能化器件对NO2气体的响应最高。反应速度快（240s），恢复速度快（280s），具有较强的NO2选择性。在建模中，设计了与NO2分子接触的氧化官能化GaN，并对其进行了几何优化。模拟结果表明，在三种金属氧化物中，TiO2官能化使吸附NO2的能量最有利的表面。此外，这些氧化官能化氮化镓的电子性质已经在总态密度（TDOS）和投射态密度（PDOS）方面进行了研究，表明与上述实验测量结果非常吻合。此外，还模拟研究了环境湿度对吸附-纳米复合材料相互作用的影响。总体而言，金属氧化物功能化显著提高了GaN气体传感器的性能，选择合适的氧化物将优化检测。
The detection of NO2 molecules by GaN nanowire sensors which were functionalized with various metal oxides have been comprehensively studied with device fabrication, characterization and modeling with first-principles calculations based on density functional theory (DFT). In this work, GaN nanowires were prepared on Si substrate by standard top-down fabrication process and then fabricated into resistor based chemical sensors. The surface of GaN nanowires were functionalized by three metal oxides: TiO2, ZnO and SnO2 for analysis. The UV illuminated device characterization results indicated that the devices with TiO2 functionalization exhibited the highest response toward NO2 gas. It showed quick response (240s) and recovery (280s) process with strong NO2 selectivity. In modeling, the oxide functionalized GaN in contact with NO2 molecule was designed and geometrically optimized. Simulation results indicated that TiO2 functionalization enabled the most energy favorable surface for NO2 adsorption among the three metal oxides. In addition, the electronic properties of these oxide functionalized GaN have been studied in terms of the total density of states (TDOS) and projected density of states (PDOS), indicating an excellent agreement with the above-mentioned experimental measurements. Furthermore, the effect of environmental humidity on the adsorbate-nanocomposite interaction has been simulated and studied. Overall, the metal oxide functionalization significantly enhances the performance of GaN gas sensors and selecting an appropriate oxide will optimize the detection.