Title

Optical Property-Based Wireless Sensors For Co2 And No Gases Using Silicon Carbide

Keywords

Carbon dioxide (CO ) 2; Gas sensor; Laser doping; Nitrogen monoxide (NO); Silicon carbide (SiC)

Abstract

Silicon carbide (SiC) is a wide bandgap semiconductor material with excellent high temperature properties, which makes it suitable for sensor applications in harsh environments. The optical properties of SiC can be changed by doping it with appropriate dopant elements for fabricating combustion gas sensors. If the dopant energy level matches the characteristic emission spectral line of any chemical, the electromagnetic wave of the chemical affects the optical properties of the semiconductor. This semiconductor optics principle is utilized to fabricate an optical sensor for combustion gases. The optical response can be detected remotely with a laser beam, such as a He-Ne laser beam of wavelength 632.8 nm, which makes it a wireless sensor. SiC has been doped with gallium and aluminum to create sensor elements for the carbon dioxide (CO2) and nitrogen monoxide (NO) gas, respectively. The dopants produce an acceptor energy level in 6H-SiC corresponding to the CO2 and NO emission spectral line 4.32 and 5.26 μ (i.e., 0.29 and 0.23 eV), respectively. The optical response of each sensor is obtained as a function of temperature. The sensor was also tested for other combustion gases such as CO and NO2. From these optical measurements, the refractive index of the Ga-doped sensor was calculated, which shows that the CO2 gas exhibits a refractive index curve that is distinctly different from the curve obtained for CO, NO and NO2 gases. The latter three gases exhibit a single refractive index curve, indicating that their interactions with SiC do not affect the Ga dopant energy level. So the Ga-doped SiC preferentially responds to CO2 gas. Similarly, the refractive index change of Al-doped 6H-SiC strongly response to NO gas and it indicates that these data can be used as sensors for the combustion gases.

Publication Date

12-1-2009

Publication Title

Proceedings of the International Instrumentation Symposium

Volume

479

Number of Pages

316-326

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

72949115263 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/72949115263

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