Abstract
The sensing properties of a surface plasmon resonance (SPR) based waveguide sensor on a wide bandgap semiconductor, silicon carbide (SiC), were studied. Compared to other waveguide sensors, the large bandgap energy of SiC material allows the sensor to operate in the visible and near infrared wavelength range, while the SPR effect by a thin gold film is expected to improve the sensitivity. The confinement factor of the sensor at various wavelengths of the incident light and refractive index of the analyte were investigated using an effective index method. Since the change of analyte type and concentration is reflected by the change of refractive index, the sensing performance can be evaluated by the shift of resonant wavelength from the confinement factor spectrum at different refractive index. The results show that the shift of resonant wavelength demonstrates linear characteristics. A sensitivity of 1928 nm/RIU (refractive index unit) shift could be obtained from the refractive index of 1.338~1.348 which attracts research interests because most biological analytes are in this range.
Highlights
In the fields of clinical diagnosis, drug detection, food safety and environmental health [1,2,3,4], and so forth, identification and quantification of biological and chemical analytes in water, blood, or other carriers, as well as detection of interactions at interfaces, are very important
Since the sensitivity S of the waveguide sensor is characterized by the change of absorbance A to the change of concentration in analyte as S ∝ ΔA/Δc = fαl when combining with (1), it is clear that a higher confinement factor indicates a better sensitivity of the waveguide sensor
The sensing performance of a silicon carbide (SiC) waveguide based surface plasmon resonance (SPR) optical sensor was characterized by the shift of the resonant wavelength of confinement factor under various refractive index of analyte
Summary
In the fields of clinical diagnosis, drug detection, food safety and environmental health [1,2,3,4], and so forth, identification and quantification of biological and chemical analytes in water, blood, or other carriers, as well as detection of interactions at interfaces, are very important. When used for chemical and biological sensing with water or water based medium, SiC is more desirable over conventional materials such as silicon (Si) because the large bandgap energy (2.2 eV in 3CSiC polytype versus 1.12 eV in Si) allows SiC waveguide sensor to operate in visible and near-infrared light range. This advantage efficiently overcomes the large absorption coefficient of water in the near infrared range, which is the challenge faced by Si with strong absorption below the wavelength of 1.1 μm. Excellent material properties such as the chemical inertness [16], radiation hardness [17], and compatibility between SiC device fabrication and standard Si device fabrication are suitable for manufacturing and on chip integration
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