Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST) , Yuseong-gu, Daejeon 305-701, Korea.
KAIST Institute for Nanocentury , Yuseong-gu, Daejeon 305-701, Korea.
Nano Lett. 2016 Jul 13;16(7):4508-15. doi: 10.1021/acs.nanolett.6b01713. Epub 2016 Jun 17.
The development of high-performance volatile organic compound (VOC) sensor based on a p-type metal oxide semiconductor (MOS) is one of the important topics in gas sensor research because of its unique sensing characteristics, namely, rapid recovery kinetics, low temperature dependence, high humidity or thermal stability, and high potential for p-n junction applications. Despite intensive efforts made in this area, the applications of such sensors are hindered because of drawbacks related to the low sensitivity and slow response or long recovery time of p-type MOSs. In this study, the VOC sensing performance of a p-type MOS was significantly enhanced by forming a patterned p-type polycrystalline MOS with an ultrathin, high-aspect-ratio (∼25) structure (∼14 nm thickness) composed of ultrasmall grains (∼5 nm size). A high-resolution polycrystalline p-type MOS nanowire array with a grain size of ∼5 nm was fabricated by secondary sputtering via Ar(+) bombardment. Various p-type nanowire arrays of CuO, NiO, and Cr2O3 were easily fabricated by simply changing the sputtering material. The VOC sensor thus fabricated exhibited higher sensitivity (ΔR/Ra = 30 at 1 ppm hexane using NiO channels), as well as faster response or shorter recovery time (∼30 s) than that of previously reported p-type MOS sensors. This result is attributed to the high resolution and small grain size of p-type MOSs, which lead to overlap of fully charged zones; as a result, electrical properties are predominantly determined by surface states. Our new approach may be used as a route for producing high-resolution MOSs with particle sizes of ∼5 nm within a highly ordered, tall nanowire array structure.
基于 p 型金属氧化物半导体 (MOS) 的高性能挥发性有机化合物 (VOC) 传感器的开发是气体传感器研究的重要课题之一，因为它具有独特的传感特性，即快速恢复动力学、低温依赖性、高湿度或热稳定性以及 p-n 结应用的高潜力。尽管在这一领域进行了大量的努力，但由于 p 型 MOS 的灵敏度低、响应慢或恢复时间长等缺点，这些传感器的应用受到了限制。在这项研究中，通过形成具有超小晶粒（约 5nm 尺寸）的超薄高纵横比（约 25）结构（约 14nm 厚）的图案化 p 型多晶 MOS，显著增强了 p 型 MOS 的 VOC 传感性能。通过二次溅射通过 Ar(+) 轰击制造了具有约 5nm 晶粒尺寸的高分辨率多晶 p 型 MOS 纳米线阵列。通过简单地改变溅射材料，很容易制造出各种 p 型纳米线阵列，如 CuO、NiO 和 Cr2O3。所制造的 VOC 传感器表现出更高的灵敏度（使用 NiO 通道在 1ppm 己烷下 ΔR/Ra = 30），以及更快的响应或更短的恢复时间（约 30s），优于以前报道的 p 型 MOS 传感器。这一结果归因于 p 型 MOS 的高分辨率和小晶粒尺寸，这导致完全充电区的重叠；因此，电特性主要由表面态决定。我们的新方法可以用作在高度有序、高大纳米线阵列结构内制造具有约 5nm 粒径的高分辨率 MOS 的途径。
