| Infrared detectors have important applications in many fields such as thermal imaging,remote sensing,and target recognition,etc.Antimonide type Ⅱ superlattice exhibits a unique energy band structure,which can be tuned by controlling its material compositions and thus is suitable for infrared detection covering the 3-30 μm mid-infrared spectral band.As compared with other infrared detectors,type Ⅱ superlattice detector has the advantages of material uniformity and low dark current,and thus is regarded as a promising candidate of the third generation of infrared detectors.Although type Ⅱ superlattice detector has achived rapid progresses in the past decade,it suffers from insufficient light absorption and limited quantum efficiency,which limit the further development and application of type Ⅱ superlattice detectors.Metasurface is an artificial periodic microstructure,which can effectively collect light energy by designing the periodic structure.Its resonance effect offers a possible way to improve light absorption and quantum efficiency in type Ⅱ superlattice detectors.In this thesis,light absorption and detection properties of metasurface-integrated type Ⅱ superlattice detectors are studied.We proposed and designed comb-shape antenna integrated type Ⅱ superlattice detectors,which exhibited enhanced light absorption and detection efficiency by using local plasmon resonance,Fabry-Perot(F-P)cavity mode and periodic microstructure-coupled waveguide mode.The interaction between antenna resonace mode and the detector material was investigated,and the enhacement on both light absorption and quantum efficiency was analysized in details.Our obtained main results are helpful for the development of high-performance type Ⅱ superlattice detectors,and are summarized as follows:(1)An In As/Ga Sb type Ⅱ superlattice detector integrated with guided mode resonant antenna was designed to achieve multi-band detection enhancement at TE polarization.Our simulation results indicated that the device structure exhibited waveguide mode and second-order F-P cavity mode at 10.15 μm and 7.65 μm,respectively.The absorption efficiencies of the detector absorption layer reached 77% and 71%,and the calculated external quantum efficiencies were 53% and 70% at the two resonance wavelengths.As compared with detector structure without antenna,external quantum efficiencies of our designed In As/Ga Sb type Ⅱ superlattice detector were increased by 4.8 and 3.8 times at the two resonance wavelengths.In addition,by adjusting the thickness of the absorption layer and the period of the Au strip antenna,the detection wavelength of the guided mode resonance was tunable withtin the band of 8 to 12 μm.(2)Ultra-thin In As/In As Sb type Ⅱ superlattice detector integrated with dual-mode resonant comb-shape antenna was proposed,which exhibited polarization insensitive enhancement in light absorption and detection.Our calculation results showed that at the detection wavelength of 4.12 μm,a local plasmon mode-coupled F-P cavity resonance was excited at TM polarization and a guided mode resonance mode was excited at TE polarization at the same time.These two modes led to 55% absorption efficiency at both polarizations within the detector absorption layer,which was enhanced by 11 times as compared with the reference structure without antenna.In the meantime,external quantum efficiency of the detector reached 55% and 40% at TM and TE polarization,respectively.Our proposed dual-mode resonant comb-shape antenna overcomed the deficiency of guided mode resonance structure,which could not achieve absorption and detection enhancement at TM polarization. |
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