High-Resolution p-Type Metal Oxide Semiconductor Nanowire Array as an Ultrasensitive Sensor for Volatile Organic Compounds.
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.
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.
Soo-Yeon
SY
Cho
The Fourth R&D Institute, Agency for Defense Development , Yuseong-gu, Daejeon 305-600, Korea.
Hae-Wook
HW
Yoo
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.
Ju Ye
JY
Kim
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.
Woo-Bin
WB
Jung
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.
Ming Liang
ML
Jin
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.
Jong-Seon
JS
Kim
Department of Nano-Structured Materials Research, Korea National Nanofab Center , Yuseong-gu, Daejeon 305-701, Korea.
Hwan-Jin
HJ
Jeon
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.
Hee-Tae
HT
Jung
gas sensor; high resolution; lithography; nanopattern; p-Type metal oxide; volatile organic compound