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▲ [13p-N106-3] Effect of LO phonon scattering on the selective IR emission from Au-GaAs stripe structures
Keywords:Thermal emission, LO phonon
The eminent advantage of phonon system in crystal semiconductors over electronic systems is the small interaction energy width with radiation field, which is applicable to photonic/optic devices within infra-red range (THz region). Previously, emission by surface phonon polariton using nanostructures of gratings, nanopillars, and so forth have been reported, whereas, metal structures have been omitted due to effects of energy broadening and high damping rate. However, we have reported significant reflectance and electric-dipole emission of s-polarized THz light resonating with the LO phonon energy from metal-GaAs surface stripe structures. [1] In this report, we discuss the dependence of optical emission spectrum on the structure dimensions of stripes: metal semiconductor width and mesa height along with the LO phonon scattering from dipole resonant polarization.
Mesa stripe structures fabricated by photolithography with wet etching process were measured using FTIR spectrometer. Figure 1 shows examples of emission spectra at approximately 630 K for the u-GaAs mesa-stripe with of 6μm. Figure 2 shows that wide mesa structures exhibit the decrease in the emission intensity as the increase in mesa height, whereas for the narrow mesa width, the intensity increases as the mesa height increases to 1mm. It is considered that the emission intensity is determined by the balance of absorption and emission. As the emission probability is highly affected by LO phonon scattering, phonon scattering takes place before the LO phonon resonant emission where absorption effect dominates with the increase in the mesa height.
Mesa stripe structures fabricated by photolithography with wet etching process were measured using FTIR spectrometer. Figure 1 shows examples of emission spectra at approximately 630 K for the u-GaAs mesa-stripe with of 6μm. Figure 2 shows that wide mesa structures exhibit the decrease in the emission intensity as the increase in mesa height, whereas for the narrow mesa width, the intensity increases as the mesa height increases to 1mm. It is considered that the emission intensity is determined by the balance of absorption and emission. As the emission probability is highly affected by LO phonon scattering, phonon scattering takes place before the LO phonon resonant emission where absorption effect dominates with the increase in the mesa height.