Broadband Tamm plasmon-enhanced planar hot-electron photodetector

High-Performance Planar Broadband Hot-Electron Photodetection through Platinum-Dielectric Triple Junctions

Recently, planar and broadband hot-electron photodetectors (HE PDs) were established but exhibited degraded performances due to the adoptions of the single-junction configurations and the utilizations of absorbable films with thicknesses larger than the electronic mean free path. In this work, we present a five-layer design for planar HE PDs assisted by triple junctions in which an ultrathin Pt layer dominates the broadband and displays strong optical absorption (>0.9 from 900 nm to 1700 nm). Optical studies reveal that the optical admittance matching between optical admittances of designed device and air at all interested wavelengths is responsible for broadband light-trapping that induces prominent energy depositions in Pt layers. Electrical investigations show that, benefitting from suppressed hot-electron transport losses and increased hot-electron harvesting junctions, the predicted responsivity of the designed HE PD is up to 8.51 mA/W at 900 nm. Moreover, the high average absorption (responsivity) of 0.96 (3.66 mA/W) is substantially sustained over a broad incidence angle regardless of the polarizations of incident light. The comparison studies between five-layer and three-layer devices emphasize the superiority of five-layer design in strong optical absorption in Pt layers and efficient hot-electron extraction.

Tamm plasmon polariton-based planar hot-electron photodetector for the near-infrared region

Light-trapping devices have always been a topic of intense interest among researchers. One such device that has gained attention is the hot-electron photodetector with a tunable detection wavelength. Photodetectors based on plasmon nanostructures that provide excitation of surface plasmon polaritons are challenging to manufacture. To address this issue, a planar hot-electron photodetector based on a Tamm plasmon polariton localized in a metal-semiconductor-multilayer mirror structure has been proposed in this study. The parameters and materials of the structure were adjusted to ensure perfect absorption at the resonance wavelength. As a result, the photoresponsivity of the proposed device can reach 42.6 mA W-1 at 905 nm. For the first time, the photosensitivity was calculated analytically by solving the dispersion law for the Tamm plasmon polariton.

Tailoring Tamm Plasmon Resonances in Dielectric Nanoporous Photonic Crystals

The fields of plasmonics and photonic crystals (PCs) have been combined to generate model light-confining Tamm plasmon (TMM) cavities. This approach effectively overcomes the intrinsic limit of diffraction faced by dielectric cavities and mitigates losses associated with the inherent properties of plasmonic materials. In this study, nanoporous anodic alumina PCs, produced by two-step sinusoidal pulse anodization, are used as a model dielectric platform to establish the methodology for tailoring light confinement through TMM resonances. These model dielectric mirrors feature highly organized nanopores and narrow bandwidth photonic stopbands (PSBs) across different positions of the spectrum. Different types of metallic films (gold, silver, and aluminum) were coated on the top of these model dielectric mirrors. By structuring the features of the plasmonic and photonic components of these hybrid structures, the characteristics of TMM resonances were studied to elucidate effective approaches to optimize the light-confining capability of this hybrid TMM model system. Our findings indicate that the coupling of photonic and plasmonic modes is maximized when the PSB of the model dielectric mirror is broad and located within the midvisible region. It was also found that thicker metal films enhance the quality of the confined light. Gas sensing experiments were performed on optimized TMM systems, and their sensitivity was assessed in real time to demonstrate their applicability. Ag films provide superior performance in achieving the highest sensitivity (S = 0.038 ± 0.001 nm ppm-1) based on specific binding interactions between thiol-containing molecules and metal films.

Multi-channel graphene-based perfect absorbers utilizing Tamm plasmon and Fabry-Perot resonances

In this paper, a multi-channel narrowband absorption structure utilizing the Tamm plasmon and Fabry-Perot resonances in the 1-2 THz range is presented. The structure consists of a graphene sheet, followed by a spacer layer and a dielectric-metal photonic crystal. The transfer matrix method (TMM) is employed to evaluate the effect of different parameters such as the constituent materials and thicknesses of the layers as well as the graphene chemical potential on the spectral response of the structure. Simulation results show that the number of channels, resonance frequencies, and absorption peaks can be easily adjusted by controlling the thicknesses and materials of the layers. The absorption value can reach as high as 99.23% for normal incidents. Additionally, perfect absorption of 100% is achievable by changing the angle of the incident light. Owing to high absorption and straightforward fabrication process, the proposed structure can find various applications such as filtering, sensing, optical switches, and thermal emissions.

Hybrid Tamm and quasi-BIC microcavity modes

The microcavity in the form of a liquid crystal defect layer embedded in a one-dimensional photonic crystal is considered. The microcavity mode has a tunable radiation decay rate in the vicinity of a bound state in the continuum. It is demonstrated that coupling between the microcavity mode and a Tamm plasmon polariton results in hybrid Tamm-microcavity modes with a tunable Q factor. The measured spectral features of hybrid modes are explained in the framework of the temporal coupled mode theory.

Ultrabroadband hot-hole photodetector based on ultrathin gold film

Hot carriers injected into semiconductor enables below-bandgap photodetection, thus attracting increasing interest. The performance of hot carrier-based device is directly related to the absorptivity of metal. Several strategies such as surface plasmons, metamaterials, and optical cavities are utilized to enhance the weak intrinsic absorption of the metal. However, the detection range is limited by their narrow resonance bandwidth alternatively. Impedance-matched absorbers, whose sheet resistance is equal to half of the free-space impedance (188 Ω), can achieve a wavelength-independent absorptivity up to 50%. Herein, we theoretically design a purely planar hot-hole photodetector based on ultrathin gold film, a new type of metallic impedance-matched absorber. Benefiting both from the efficient absorption and ultrathin nature of the film, we predict that the photoresponsivity of our device can reach 35.7 mA W^-1 under zero bias at the wavelength of 1.3 μm, with a full width at half maximum (FWHM) of detection range reaching 1050 nm, setting a new record for the bandwidth of the hot carrier photodetectors. We also demonstrated that the device is robust to the incident angle and can be tuned through the external bias voltage. This work provides a pathway for broadband hot carrier detectors and other hot carrier-based applications.

Plasmonic hot-electron reconfigurable photodetector based on phase-change material Sb2S3

Hot-carrier based photodetectors and enhanced by surface plasmons (SPs) hot-electron injection into semiconductors, are drawing significant attention. This photodetecting strategy yields to narrowband photoresponse while enabling photodetection at sub-bandgap energies of the semiconductor materials. In this work, we analyze the design of a reconfigurable photodetector based on a metal-semiconductor (MS) configuration with interdigitated dual-comb Au electrodes deposited on the semiconducting Sb₂S₃ phase-change material. The reconfigurability of the device relies on the changes of refractive index between the amorphous and crystalline phases of Sb₂S₃ that entail a modulation of the properties of the SPs generated at the dual-comb Au electrodes. An exhaustive numerical study has been realized on the Au grating parameters formed by the dual-comb electrodes, and on the SP order with the purpose of optimizing the absorption of the device, and thus, the responsivity of the photodetector. The optimized photodetector layout proposed here enables tunable narrowband photodetection from the O telecom band (λ = 1310 nm) to the C telecom band (λ = 1550 nm).

Five-layer planar hot-electron photodetectors at telecommunication wavelength of 1550 nm

Cost-effective and high-responsivity photodetectors at a telecommunication wavelength of 1550 nm are highly desired in optical communication systems. Differing from conventional semiconductor-based photodetectors, several planar hot-electron photodetectors (HE PDs) that operate at 1550 nm have been reported. However, these devices were often comprised of many planar layers and exhibited relatively low responsivities. Herein, we propose a design of high-performance planar HE PDs consisting of five layers. Utilizing Fabry-Pérot (FP) resonance, the nearly perfect absorption of the proposed device can be achieved at the targeted wavelength of 1550 nm. Simulation results show that FP resonance orders are crucial for the optical absorption efficiencies, and then electrical responses. Analytical electrical calculations reveal that, benefiting from the strong absorption (>0.6) in the ultrathin Au layer with a thickness of 5 nm and the low Schottky barrier (0.5 eV) of Au-MoS₂ contact, predicted responsivity of proposed HE PD at zero-order FP resonance is up to ∼10 mA/W. Our design provides a new approach to realize low-cost and efficient photodetection for optical communication technology.

Selective Properties of Mid-Infrared Tamm Phonon-Polaritons Emitter with Silicon Carbide-Based Structures

Electromagnetic (EM) absorbers and emitters have attracted much interest because of their versatile applications. A photonic heterostructure composed of silicon carbide (SiC) layer/germanium (Ge) cavity/distributed Bragg reflector (DBR) has been proposed. Selective emission properties have been investigated through rigorous coupled wave analysis (RCWA) method. The results illustrate that Tamm phonon-polaritons can be excited, and the magnetic field is partially centralized at the junction of Ge cavity and SiC film, aimed to improve the interactions of photon-phonon. The absorptivity/emissivity of the structure can be better optimized by controlling the coupling of surface modes with the incident wave. Near-unity absorption can be achieved through optimizing the SiC grating/Ge cavity/distributed Bragg reflector (DBR) multilayer structure with geometrical parameters of d_s = 0.75 μm, d_g = 0.7 μm, d₁ = 1.25 μm and d₂ = 0.75 μm, respectively. Physical mechanism of selective emission characteristics is deliberated. In addition, the simulation results demonstrate that the emitter desensitizes to the incidence angle and polarization state in the mid-infrared (MIR) range. This research ameliorates the function of the selective emitters, which provides more efficient design for SiC-based systems.

Broadband Tamm Plasmons in Chirped Photonic Crystals for Light-Induced Water Splitting

An electrode of a light-induced cell for water splitting based on a broadband Tamm plasmon polariton localized at the interface between a thin TiN layer and a chirped photonic crystal has been developed. To facilitate the injection of hot electrons from the metal layer by decreasing the Schottky barrier, a thin n-Si film is embedded between the metal layer and multilayer mirror. The chipping of a multilayer mirror provides a large band gap and, as a result, leads to an increase in the integral absorption from 52 to 60 percent in the wavelength range from 700 to 1400 nm. It was shown that the photoresponsivity of the device is 32.1 mA/W, and solar to hydrogen efficiency is 3.95%.

Planar narrowband Tamm plasmon-based hot-electron photodetectors with double distributed Bragg reflectors

Hot-electron photodetectors (HE PDs) are attracting a great deal of attention from plasmonic community. Many efficient HE PDs with various plasmonic nanostructures have been demonstrated, but their preparations usually rely on complicated and costly fabrication techniques. Planar HE PDs are viewed as potential candidates of cost-effective and large-area applications, but they likely fail in the simultaneous achievement of outstanding optical absorption and hot-electron collection. To reconcile the contradiction between optical and electrical requirements, herein, we propose a planar HE PD based on optical Tamm plasmons (TPs) consisted of an ultrathin gold film (10 nm) sandwiched between two distributed Bragg reflectors (DBRs). Simulated results show that strong optical absorption (>0.95) in the ultrathin Au film is realized. Electrical calculations show that the predicted peak photo-responsivity of proposed HE PD with double DBRs is over two times larger than that of conventional single-DBR HE PD. Moreover, the planar dual-DBR HE PDs exhibit a narrowband photodetection functionality and sustained performance under oblique incidences. The optical nature associated with TP resonance is elaborated.

Simulated Study of High-Sensitivity Gas Sensor with a Metal-PhC Nanocavity via Tamm Plasmon Polaritons

An optical configuration was designed and simulated with a metal-photonic crystal (PhC) nanocavity, which had high sensitivity on gas detection. The simulated results shows that this configuration can generate a strong photonic localization through exciting Tamm plasmon polaritons. The strong photonic localization highly increases the sensitivity of gas detection. Furthermore, this configuration can be tuned to sense gases at different conditions through an adjustment of the detection light wavelength, the period number of photonic crystal and the thickness of the gas cavity. The sensing routes to pressure variations of air were revealed. The simulation results showed that the detection precision of the proposed device for gas pressure could reach 0.0004 atm.

Broadband wide-angle multilayer absorber based on a broadband omnidirectional optical Tamm state

Recently, broadband optical Tamm states (OTSs) in heterostructures composed of highly lossy metal layers and all-dielectric one-dimensional (1D) photonic crystals (PhCs) have been utilized to realize broadband absorption. However, as the incident angle increases, the broadband OTSs in such heterostructures shift towards shorter wavelengths along the PBGs in all-dielectric 1D PhCs, which strongly limits the bandwidths of wide-angle absorption. In this paper, we realize a broadband omnidirectional OTS in a heterostructure composed of a Cr layer and a 1D PhC containing layered hyperbolic metamaterials with an angle-insensitive photonic band gap. Assisted by the broadband omnidirectional OTS, broadband wide-angle absorption can be achieved. High absorptance (A > 0.85) can be remained when the wavelength ranges from 1612 nm to 2335 nm and the incident angle ranges from 0° to 70°. The bandwidth of wide-angle absorption (0°-70°) reaches 723 nm. The designed absorber is a lithography-free 1D structure, which can be easily fabricated under the current magnetron sputtering or electron-beam vacuum deposition technique. This broadband, wide-angle, and lithography-free absorber would possess potential applications in the design of photodetectors, solar thermophotovoltaic devices, gas analyzers, and cloaking devices.