Sosada-Ludwikowska F, Reiner L, Egger L, Lackner E, Krainer J, Wimmer-Teubenbacher R, Singh V, Steinhauer S, Grammatikopoulos P, Koeck A
Materials Center Leoben Forschung GmbH 8700 Leoben Austria.
Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST), Graduate University 904-0495 Okinawa Japan.
Nanoscale Adv. 2024 Jan 15;6(4):1127-1134. doi: 10.1039/d3na00552f. eCollection 2024 Feb 13.
Smart gas-sensor devices are of crucial importance for emerging consumer electronics and Internet-of-Things (IoT) applications, in particular for indoor and outdoor air quality monitoring (, CO levels) or for detecting pollutants harmful for human health. Chemoresistive nanosensors based on metal-oxide semiconductors are among the most promising technologies due to their high sensitivity and suitability for scalable low-cost fabrication of miniaturised devices. However, poor selectivity between different target analytes restrains this technology from broader applicability. This is commonly addressed by chemical functionalisation of the sensor surface catalytic nanoparticles. Yet, while the latter led to significant advances in gas selectivity, nanocatalyst decoration with precise size and coverage control remains challenging. Here, we present CMOS-integrated gas sensors based on tin oxide (SnO) films deposited by spray pyrolysis technology, which were functionalised with platinum (Pt) nanocatalysts. We deposited size-selected Pt nanoparticles (narrow size distribution around 3 nm) by magnetron-sputtering inert-gas condensation, a technique which enables straightforward surface coverage control. The resulting impact on SnO sensor properties for CO and volatile organic compound (VOC) detection functionalisation was investigated. We identified an upper threshold for nanoparticle deposition time above which increased surface coverage did not result in further CO or VOC sensitivity enhancement. Most importantly, we demonstrate a method to adjust the selectivity between these target gases by simply adjusting the Pt nanoparticle deposition time. Using a simple computational model for nanocatalyst coverage resulting from random gas-phase deposition, we support our findings and discuss the effects of nanoparticle coalescence as well as inter-particle distances on sensor functionalisation.
智能气体传感器设备对于新兴的消费电子产品和物联网（IoT）应用至关重要，特别是用于室内和室外空气质量监测（如一氧化碳水平）或检测对人体健康有害的污染物。基于金属氧化物半导体的化学电阻式纳米传感器是最有前途的技术之一，因为它们具有高灵敏度且适合以低成本大规模制造小型化设备。然而，不同目标分析物之间的选择性较差限制了该技术的更广泛应用。这通常通过传感器表面催化纳米颗粒的化学功能化来解决。然而，尽管后者在气体选择性方面取得了重大进展，但精确控制尺寸和覆盖率的纳米催化剂修饰仍然具有挑战性。在这里，我们展示了基于喷雾热解技术沉积的氧化锡（SnO）薄膜的CMOS集成气体传感器，这些传感器用铂（Pt）纳米催化剂进行了功能化。我们通过磁控溅射惰性气体凝聚沉积了尺寸选择的Pt纳米颗粒（3nm左右的窄尺寸分布），这是一种能够直接控制表面覆盖率的技术。研究了由此对SnO传感器用于检测CO和挥发性有机化合物（VOC）的性能及功能化的影响。我们确定了纳米颗粒沉积时间的上限，超过该上限，表面覆盖率的增加不会导致CO或VOC灵敏度的进一步提高。最重要的是，我们展示了一种通过简单调整Pt纳米颗粒沉积时间来调节这些目标气体之间选择性的方法。使用一个简单的计算模型来描述随机气相沉积产生的纳米催化剂覆盖率，我们支持了我们的发现，并讨论了纳米颗粒聚结以及颗粒间距离对传感器功能化的影响。
