Structural, optical and gas sensing properties of vertically well-aligned ZnO nanowires grown on graphene/Si substrate by thermal evaporation method
- Technical Equipment and Allocation Administration, Ministry of Public Security, 47 Pham Van Dong, Cau Giay, Ha Noi (Viet Nam)
- Faculty of Materials Technology, Ho Chi Minh city University of Technology, VNU-HCM, 268 Ly Thuong Kiet street, Ward 14, District 10, Ho Chi Minh City (Viet Nam)
- Institute of Chemistry and Materials, 17 Hoang Sam, Cau Giay, Ha Noi (Viet Nam)
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)
Highlights: • Vertically well-aligned ZnO NW arrays with high aspect ratio and extremely large-surface-volume ratio were synthesized on graphene/Si substrate without the aid of metal catalyst by a simple thermal evaporation. • The gas sensor based on the vertical ZnO NW arrays-graphene structure exhibited high sensitivity and rapid response/recovery characteristics to NO{sub 2} gas at 200oC, and could be used to detect NO{sub 2} gas at very low levels (2, 6, 10 ppm). • The excellent sensing performance is mainly because of the large specific surface area and the presence of oxygen-vacancies at the surface of ZnO NWs, together with the creation of p-n heterojunctions between n-type ZnO NW and p-type graphene. • The common defects and optical properties of the ZnO NW arrays-graphene structure were studied in detail. • The possible growth mechanism of vertically well-aligned ZnO NWs on graphene and the gas-sensing mechanism of sensors were proposed. - Abstract: We report catalyst-free vertical growth of high-density ZnO nanowire (NW) arrays on Si substrate with a graphene buffer layer by thermal evaporation method. Structural, surface morphology, chemical composition and optical properties of ZnO NWs were studied by Field emission scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and Raman spectroscopy. The results indicate that the grown ZnO NWs are single-crystalline and exhibit the hexagonal wurtzite crystal structure with a preferred orientation along the [0001] direction; all of the ZnO NWs vertically grow on the graphene/Si substrate. The majority of the as-grown NWs have diameters in the range of 250–300 nm and length up to several tens of micrometers, whereas a small portion of NWs have a diameter of approximately of 9–12 nm. Room temperature PL spectrum of the ZnO NWs exhibits a sharp and strong ultraviolet emission at 380 nm and a weak visible emission at around 516 nm. The role of graphene buffer layer in the vertical-aligned ZnO NW arrays growth and its improved optical properties is demonstrated. Importantly, the gas sensor based on these ZnO NWs exhibits high sensitivity and rapid response/recovery characteristics to NO{sub 2} gas at 200 °C, and can detect NO{sub 2} concentration as low as 2, 6 and 10 ppm. The excellent sensing performance is mainly due to the combination of the large specific surface area and the presence of oxygen-vacancies at the surface of ZnO NWs, together with the creation of p-n heterojunctions between n-type ZnO NW and p-type graphene. Such a ZnO NW/graphene structure is very promising for various applications, such as photonic, optoelectronic and sensor devices. In addition, the possible growth mechanism and the NO{sub 2} sensing gas mechanism of the ZnO NWs-graphene structure have been discussed.
- OSTI ID:
- 22805046
- Journal Information:
- Materials Characterization, Vol. 141; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis of a Hybrid Nanostructure of ZnO-Decorated MoS2 by Atomic Layer Deposition
Schottky-contacted vertically self-aligned ZnO nanorods for hydrogen gas nanosensor applications
Related Subjects
CATALYSTS
FIELD EMISSION
FOURIER TRANSFORM SPECTROMETERS
GRAPHENE
INFRARED SPECTRA
LAYERS
NANOWIRES
NITROGEN DIOXIDE
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
P-N JUNCTIONS
RAMAN SPECTROSCOPY
SCANNING ELECTRON MICROSCOPY
SILICON
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
ULTRAVIOLET RADIATION
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
ZINC OXIDES