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Browsing by Subject "Infrared"

Now showing 1 - 2 of 2
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    Design and fabrication of state of the art uncooled thermopile infrared detectors with cavity coupled absorption
    (2013-06) Shea, Ryan Patrick
    We present the design, fabrication, and characterization of uncooled thermopile infrared detectors with cavity coupled absorption in the long wave infrared with performance exceeding all published works. These detectors consist of a two die optical cavity which enhances absorption in the desired spectral range while rejecting unwanted noise off resonance. The electrical transduction mechanism is a thermopile consisting of four thermoelectric junctions of co-sputtered Bi2Te3 and Sb2<\sub>Te3<\sub> having a room temperature unitless thermoelectric figure of merit of .43. Processing steps are described in detail for the fabrication of extremely thermally isolated structures necessary for highly sensitive detectors. Optical characterization of the devices reveals a responsivity of 4700 V/W, thermal time constant of 58 ms, and specific detectivity of at least 3.0x109<\super> cmHz1/2/W. Also presented are a theoretical proposal for a midwave infrared detector using semiconductor selective absorption to enhance detectivity beyond the blackbody radiation limit and a new method for the analysis of radiation thermal conduction in highly thermally isolated structures.
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    Dusty Lyman-alpha emitters as seen by Spitzer
    (2014-06) Dolan, Kyle Arthur
    We present an analysis of Spitzer data for a large sample of low-redshift Lyα-emitting galaxies discovered by GALEX. Using the Donley et al. (2012) AGN selection region in color-color space IRAC photometry, we determined from our sample that the LAEs at z~0.3 have an AGN fraction of ~24%. The total bolometric LIR for the sample was found using χ2 fitting along with template SEDs, and we found that the galaxies ranged from 108.05LSun to 1011.57LSun, with a median LIR value of 1010.39LSun. LIR and LLyα for our sample do not appear to be correlated, unlike the high-LIIRLyα-emitting objects examined by Colbert et al. (2006) and Nilsson & Mller (2009), which may mean that their samples of LAEs, with LIR/LSun > 1012, are qualitatively different from our own. The SFR values for the sample have a median value of 5.63 MSun yr-1, in agreement with the value of 6MSun yr-1 found in Cowie et al. (2011). Also, we find that most of the sample has a contribution of SFRIR to SFRTotal that is greater than 60%, indicating that these LAEs have a significant amount of dust extinction, and SFRUV alone is also not a good indicator for SFRTotal. From comparing dust extinction to UV continuum slope , it was found that LAEs do not follow the same curves predicted for SF or SB galaxies, indicating that LAEs at low redshift may experience more variation in their native UV spectra, making it impossible to recover their dust attenuation from their UV slope. This would suggest that LAEs may consist of stellar populations of varying ages, leading to more intrinsic variation in their UV slope.