24 September 2009 Laser fabrication of silicon carbide detector for gas sensing and focal plane array imaging
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A Mid-Wave Infra-Red (MWIR) detector is developed by doping an n-type 4H-SiC with an appropriate dopant to create a dopant energy level that matches with a quantum of energy for the wavelength of interest. The detector absorbs the photons and the absorbed photon energy modifies the electron density in the semiconductor by the photoexcitation, leading to changes in the refraction index. Ga is known to have an energy level of 0.30 eV in n-type 4H-SiC substrates, which corresponds to the wavelength 4.21 μm. A detector was fabricated for the MWIR wavelength of 4.21 μm by doping n-type 4H-SiC with Ga. The dopant energy level was confirmed by optical absorption measurements in the wavelength range of 4 to 5 μm. The optical response of the detector to the wavelength 4.21 μm was determined by measuring the reflectivity of the detector using a He-Ne laser of wavelength 632.8 nm as the probe beam. The reflectivity data were used to calculate the variation in the refraction index of the detector at the MWIR wavelength of interest and the selectivity of the detector was established by testing the sensor response to that of an as-received sample. The comparison yielded a distinct change in the refraction index curve for the detector, indicating that the detector is suitable for applications at the wavelength 4.21 μm.
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Geunsik Lim, Geunsik Lim, Tariq Manzur, Tariq Manzur, Aravinda Kar, Aravinda Kar, } "Laser fabrication of silicon carbide detector for gas sensing and focal plane array imaging", Proc. SPIE 7480, Unmanned/Unattended Sensors and Sensor Networks VI, 74800Y (24 September 2009); doi: 10.1117/12.835084; https://doi.org/10.1117/12.835084

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