Research ArticleSEMICONDUCTORS

Near-infrared–to–visible highly selective thermal emitters based on an intrinsic semiconductor

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Science Advances  23 Dec 2016:
Vol. 2, no. 12, e1600499
DOI: 10.1126/sciadv.1600499
  • Fig. 1 Theoretical calculation results.

    (A) Spectral emissivity and (B) spectral radiance of Si rod-array emitter (solid lines) in the direction normal to the surface at 1400 K with a = 500 nm, h = 450 nm, r = 110 nm, and tSi = 50 nm. The inset in (A) illustrates the emitter structure and parameters. (C) Radiation angle dependence of emission intensity at 1400 K for the emitter with a 1-m2 area. (D) Radiation spectra of Si rod-array emitters at 1400 K integrated over the upper hemisphere with structural parameters a = 500 nm, h = 450 nm, r = 110 nm, and tSi = 50 nm (solid black line); a = 600 nm, h = 600 nm, r = 105 nm, and tSi = 0 nm (solid red line); and a = 700 nm, h = 800 nm, r = 190 nm, and tSi = 0 nm (solid green line). The blackbody spectrum at 1400 K integrated over the upper hemisphere (dashed line) and the irradiance of sunlight at AM1.5G (gray line) are also plotted.

  • Fig. 2 Experimental results.

    (A) Scanning electron microscope image of a fabricated sample with r = 105 nm. (B) Measured thermal emissivity of Si rod arrays (solid red lines) with r values of 105, 90, and 85 nm at 1273 K in surface normal direction in the near-infrared range. The theoretically calculated emissivity spectra are indicated by solid blue lines. (C) Measured wide-range emissivity spectra of Si rod arrays at 1273 K. The emissivity peak at 4200 nm is due to absorption by CO2.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/12/e1600499/DC1

    Material selection

    Absorption coefficient of Si

    Thermal radiation spectra of n-doped Si rod-array emitters

    fig. S1. Spectral irradiance of the sun [air mass 1.5 global (AM1.5G)] and blackbody radiation spectra integrated over a hemisphere at various temperatures.

    fig. S2. Theoretical absorption coefficient of Si at various temperatures on a linear scale and a log-log scale.

    fig. S3. Theoretical thermal radiation power density spectra of structurally identical Si rod-array emitters with different doping densities at 1400 K.

    table S1. Doping density dependence of the energy utilization efficiency of structurally identical Si rod-array emitters.

    References (2730)

  • Supplementary Materials

    This PDF file includes:

    • Material selection
    • Absorption coefficient of Si
    • Thermal radiation spectra of n-doped Si rod-array emitters
    • fig. S1. Spectral irradiance of the sun air mass 1.5 global (AM1.5G) and blackbody radiation spectra integrated over a hemisphere at various temperatures.
    • fig. S2. Theoretical absorption coefficient of Si at various temperatures on a linear scale and a log-log scale.
    • fig. S3. Theoretical thermal radiation power density spectra of structurally identical Si rod-array emitters with different doping densities at 1400 K.
    • table S1. Doping density dependence of the energy utilization efficiency of structurally identical Si rod-array emitters.
    • References (27–30)

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