Journal
SENSORS AND ACTUATORS B-CHEMICAL
Volume 212, Issue -, Pages 84-92Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.snb.2015.02.009
Keywords
CVD graphene; Sol-gel TiO2; TiO2/graphene interface; p-n heterojunction; I-V characteristics; H-2 sensor
Funding
- CSIR Govt. of India
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Thermally oxidized p-type Si [resistivity (5-10) Omega cm and < 1 0 0 > orientation] with oxide thickness of 245 nm was used as the substrate for the deposition of graphene by CVD. The formation of multilayer graphene (MLG) was confirmed by Raman spectroscopy. A heterojunction was fabricated by sol-gel coating of TiO2 on CVD grown graphene layer. The formation of titanium dioxide was verified by electron dispersion spectroscopy (EDS). The surfaces of TiO2, graphene as well as p-TiO2/n-graphene interface were characterized by scanning electron microscopy (SEM). Detail sensor study of the p-TiO2/n-graphene heterojunction was performed by taking two lateral catalytic metal (Pd) contacts deposited by e-beam evaporation. The response time of 16 s and the corresponding recovery time of 61 s were obtained for 0.5% H-2 in air at 125 degrees C. The p-TiO2/n-graphene junction showed selectivity for H-2 compared to methane. The stability study was performed and it showed almost the steady results over a period of 3 days as tested by the discrete measurements. The sensing mechanism was formulated using a simplified energy band diagram. (C) 2015 Elsevier B.V. All rights reserved.
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