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Highly Sensitive H2S Sensor Based on the Metal-Catalyzed SnO2 Nanocolumns Fabricated by Glancing Angle Deposition.

Yoo KS, Han SD, Moon HG, Yoon SJ, Kang CY - Sensors (Basel) (2015)

Bottom Line: After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure.The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s.These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48).

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, University of Seoul, 163, Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea. ksyoo@uos.ac.kr.

ABSTRACT
As highly sensitive H2S gas sensors, Au- and Ag-catalyzed SnO2 thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure. The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s. These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48).

No MeSH data available.


(a) A schematic diagram of the e-beam evaporation using the glancing angle deposition technique; (b) Deposition condition of the sensors.
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sensors-15-15468-f001: (a) A schematic diagram of the e-beam evaporation using the glancing angle deposition technique; (b) Deposition condition of the sensors.

Mentions: The substrate used for these sensors was the SiO2/Si wafer with Pt/Ti interdigitated electrodes (IDEs) that is comprised of an inter-electrode gap of 5 µm. The thicknesses of the Pt/Ti IDEs were 100 nm/50 nm, respectively, and IDEs were fabricated by photolithography and dry etching. SnO2 thin films of a 100 nm thickness (subsequently referred to as “SnO2 thin film sensor”) were deposited onto the substrate at an ambient temperature using an e-beam evaporator under 2 × 10−5 Torr. In the same manner, SnO2 thin films with nanocolumn morphology using the GAD technique (subsequently referred to as “SnO2 nanocolumn sensor”) were evaporated at a glancing angle of 85°, based on previous research [29]. The glancing vapor flux of atom randomly forms an initial nucleus like a nanoisland on the substrate. The initial nucleus makes a self-shadowed region that is not deposited on the opposite side of vapor flux. Next, continually growing up along one side by glancing vapor, the porous nanocolumns are formed on the tilt. In addition, Au or Ag of a 5 nm thickness was deposited onto the SnO2 nanocolumns. A schematic diagram of the e-beam evaporation as a function of the incident angle using the GAD technique and the details of the deposition conditions are shown in Figure 1. After the deposition, these thin films and nanocolumns were annealed at 500 °C for 40 h in air to produce SnO2 polycrystalline and metal nanoislands by aggregation.


Highly Sensitive H2S Sensor Based on the Metal-Catalyzed SnO2 Nanocolumns Fabricated by Glancing Angle Deposition.

Yoo KS, Han SD, Moon HG, Yoon SJ, Kang CY - Sensors (Basel) (2015)

(a) A schematic diagram of the e-beam evaporation using the glancing angle deposition technique; (b) Deposition condition of the sensors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541839&req=5

sensors-15-15468-f001: (a) A schematic diagram of the e-beam evaporation using the glancing angle deposition technique; (b) Deposition condition of the sensors.
Mentions: The substrate used for these sensors was the SiO2/Si wafer with Pt/Ti interdigitated electrodes (IDEs) that is comprised of an inter-electrode gap of 5 µm. The thicknesses of the Pt/Ti IDEs were 100 nm/50 nm, respectively, and IDEs were fabricated by photolithography and dry etching. SnO2 thin films of a 100 nm thickness (subsequently referred to as “SnO2 thin film sensor”) were deposited onto the substrate at an ambient temperature using an e-beam evaporator under 2 × 10−5 Torr. In the same manner, SnO2 thin films with nanocolumn morphology using the GAD technique (subsequently referred to as “SnO2 nanocolumn sensor”) were evaporated at a glancing angle of 85°, based on previous research [29]. The glancing vapor flux of atom randomly forms an initial nucleus like a nanoisland on the substrate. The initial nucleus makes a self-shadowed region that is not deposited on the opposite side of vapor flux. Next, continually growing up along one side by glancing vapor, the porous nanocolumns are formed on the tilt. In addition, Au or Ag of a 5 nm thickness was deposited onto the SnO2 nanocolumns. A schematic diagram of the e-beam evaporation as a function of the incident angle using the GAD technique and the details of the deposition conditions are shown in Figure 1. After the deposition, these thin films and nanocolumns were annealed at 500 °C for 40 h in air to produce SnO2 polycrystalline and metal nanoislands by aggregation.

Bottom Line: After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure.The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s.These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48).

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, University of Seoul, 163, Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea. ksyoo@uos.ac.kr.

ABSTRACT
As highly sensitive H2S gas sensors, Au- and Ag-catalyzed SnO2 thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure. The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s. These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48).

No MeSH data available.