Title

Wireless Chemical Sensor For Combustion Species At High Temperatures Using 4H-Sic

Abstract

Crystalline silicon carbide (SiC) is an attractive wide bandgap semiconductor material for gas sensor applications in harsh environments because of its high mechanical strength and chemical inertness at elevated temperatures. The optical properties of 4H-SiC can be changed by doping it with appropriate dopant elements to create a dopant energy level that matches with the characteristic emission spectral line of the combustion gas. The radiation emitted by the gas of interest changes the electron density in the semiconductor by the photoexcitation and, thereby, alters the refractive index of the sensor. Since the 4H-SiC substrate inherently acts as a Fabry-pérot interferometer, the experimental data yield an inteferrometric pattern for the reflected power of a He-Ne laser of wavelength 632.8 nm as a function of temperature. The variation of the refractive index has been obtained from this pattern up to 650°C, which provides a mechanism for constructing wireless chemical sensors. A gallium-doped 4H-SiC sensor with dopant energy level E v + 0.30 eV showed a distinct refractive index curve for CO 2, which was different from the curves obtained for NO and NO 2 gases. The dopant energy level is confirmed from optical absorption measurements in the wavelength range of 0.2 to 25 m. The selective changes in the refractive index due to CO2 indicate that the Ga-doped 4H-SiC substrate can be used as a wireless CO2 gas sensor.

Publication Date

1-1-2010

Publication Title

Ceramic Engineering and Science Proceedings

Volume

31

Issue

9

Number of Pages

109-118

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/9780470944080.ch12

Socpus ID

79952381717 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/79952381717

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