Heavily Doped Semiconductor Metamaterials for Mid‐Infrared Multispectral Perfect Absorption and Thermal Emission

Abstract

A metamaterial perfect absorber based on layered, doped and undoped semiconductors is experimentally and theoretically investigated. Design rules are given to control the multispectral, narrow, strong absorption features (>98% absorption) in the mid‐IR spectrum. The proposed sub‐wavelength grating structures support localized surface plasmons and photonic resonances associated to the quarter wavelength optical thickness of the undoped spacer layer. The resonances hybridize depending on the geometric setup of the metamaterial and the material properties of the heavily doped semiconductor. The angular response of the resonances is studied to determine the acceptance angle. While the absorption is best at near‐normal incidence, the spectral position of the absorption bands is weakly dependent on the angular incidence up to angles of 45°. Complementary to the polarization‐dependent grating design of the metamaterial, an alternative based on a crossed grating nanopattern is also investigated for polarization insensitivity. Furthermore, it is demonstrated that the metamaterial perfect absorber provides a tailored thermal emission spectrum. Based on the heavily doped InAsSb/GaSb metamaterial platform, integrable and miniaturized perfect absorbers and thermal sources can be built.

Surface-Enhanced Thermal Emission Spectroscopy with Perfect Absorber Metasurfaces

“…This can be explained by defects and carrier trapping due to the technological processing and is discussed in more detail in reference. 49 After this fitting procedure, a 2 nm thin material layer was added to the model, representing the thickness of a PFTMS monolayer. Absorbance band fitting was performed using the IR spectrum of PFTMS to extract the dielectric function as a sum of 21 Lorentz oscillators (see Supporting Information, Figure S1).…”

“…The two resonances in Figure a correspond to an antireflectance effect at 1038 cm –1 , depending on the quarter-wavelength optical thickness of the dielectric spacer layer and a surface plasmon resonance close to 810 cm –1 , presenting the emittance maximum for the investigated sample or, in other terms, a reflectance below 0.01. These resonances may hybridize as discussed elsewhere, giving a plasmonic character to the “quarter-wavelength” resonance. In the opposite polarization, parallel to the grating’s grooves, the emission peak is linked to the quarter-wavelength optical thickness reflectance minimum.…”

“…48 Using a layer system of InAsSb:Si as a metal-like material stacked with GaSb as spacer, near perfect absorption can be achieved. 49 When the system is at resonance, the effective optical impedance equals the free space impedance so that reflection is suppressed. Simultaneously, transmission is avoided due to the optically thick heavily doped semiconductor (InAsSb:Si) metal-like ground plane.…”

“…Using a layer system of InAsSb:Si as a metal-like material stacked with GaSb as spacer, near perfect absorption can be achieved . When the system is at resonance, the effective optical impedance equals the free space impedance so that reflection is suppressed.…”

Sensing, Switching and Modulating Applications of a Superconducting THz Metamaterial

“…The emergence of planar metamaterials has opened a gateway to unprecedented electromagnetic properties and functionality unattainable from naturally occurring materials, thus enabling a family of PrMM based devices such as biosensors [26]- [33], biomedical detectors [34]- [36], optical non-linear liquid sensors [37]- [40], chemical sensors [41]- [43], glucose sensors [44], [45], slow light devices [46]- [49], optical buffering [50], [51], modulator devices [52]- [54], super lenses [55], [56], cloak designs [57], [58], and switches [59], [60]. The response of PrMMs can also be engineered to mimic EM response in all frequency regimes such as visible [61]- [64], near-infrared [39], [40], [45], [65]- [68], mid-infrared [59]- [72], far-infrared [73]- [75], and THz [41], [47], [7], [77]- [80].…”