Resonant-cavity-enhanced mid-infrared photodetector on a silicon platform (original) (raw)
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Monolithically integrated, resonant-cavity-enhanced dual-band mid-infrared photodetector on silicon
Applied Physics Letters, 2012
In this paper, we present experimental demonstration of a resonant-cavity-enhanced mid-infrared photodetector monolithically fabricated on a silicon substrate. Dual-band detection at 1.6 lm and 3.7 lm is achieved within a single detector pixel without cryogenic cooling, by using thermally evaporated nanocrystalline PbTe as the photoconductive absorbers. Excellent agreement between theory and experiment is confirmed. The pixel design can potentially be further extended to realizing multispectral detection. V
Mid-infrared materials and devices on a Si platform for optical sensing
Science and Technology of Advanced Materials, 2014
In this article, we review our recent work on mid-infrared (mid-IR) photonic materials and devices fabricated on silicon for on-chip sensing applications. Pedestal waveguides based on silicon are demonstrated as broadband mid-IR sensors. Our low-loss mid-IR directional couplers demonstrated in SiN x waveguides are useful in differential sensing applications. Photonic crystal cavities and microdisk resonators based on chalcogenide glasses for high sensitivity are also demonstrated as effective mid-IR sensors. Polymer-based functionalization layers, to enhance the sensitivity and selectivity of our sensor devices, are also presented. We discuss the design of mid-IR chalcogenide waveguides integrated with polycrystalline PbTe detectors on a monolithic silicon platform for optical sensing, wherein the use of a low-index spacer layer enables the evanescent coupling of mid-IR light from the waveguides to the detector. Finally, we show the successful fabrication processing of our first prototype mid-IR waveguide-integrated detectors.
Applied Physics Letters, 2020
The design, fabrication, and characterization of a resonant cavity-enhanced photodetector (RCE PD) operating in the long-wavelength infrared regime are demonstrated. The incorporation of the low bandgap InAs/InAs 0:70 Sb 0:30 type-II strained-layer superlattice into the absorber layer of the detector cavity, along with the high-reflectivity (R m > 0.9) AlAs 0:08 Sb 0:92 /GaSb distributed Bragg reflector pairs, results in resonant enhancement at 7.7-7.8 lm, which is a spectral region relevant in applications in sensing of chemical warfare agents and in medical biomarker diagnostics. These resonant wavelength peaks also display a high quality factor in the range of 76-86 and a small temperature coefficient of 0.52 nm K À1. An nBn architecture, where an Al 0:71 Ga 0:29 As 0:08 Sb 0:92 layer acts as a barrier for majority electrons while minimizing the valence band offset with the absorber, is also incorporated into the cavity in order to improve the electrical properties of the detector. Spectral response measurements yield a peak external quantum efficiency of 14.6% and a peak responsivity of 0.91 A W À1 at 77 K and À0.8 V; meanwhile, a dark current density of 2.0 Â 10 À4 A cm À2 at 77 K results in a specific detectivity of 3.7 Â 10 10 cm Hz 1=2 W À1 , coming close to the theoretical background-limited D Ã of an ideal broadband photovoltaic detector with the superlattice composition as that of the RCE PD.
Sensitivity Comparison of Integrated Mid-Infrared Silicon-Based Photonic Detectors
Proceedings, 2018
Integrated silicon photonics in the mid-infrared is a promising platform for cheap and miniaturized chemical sensors, including gas and/or liquid sensors for environmental monitoring and the consumer electronics market. One major challenge in integrated photonics is the design of an integrated detector sensitive enough to detect minimal changes in light intensity resulting from, for example, the absorption by the analyte. Further complexity arises from the need to fabricate such detectors at a high throughput with high requirements on fabrication tolerances. Here we analyze and compare the sensitivity of three different chip-integrated detectors at a wavelength of 4.17 µm, namely a resistance temperature detector (RTD), a diode and a vertical-cavity enhanced resonant detector (VERD).
Resonant cavity-enhanced (RCE) photodetectors
IEEE Journal of Quantum Electronics, 1991
The photosensitivity characteristics of resonant cavity-enhanced (RCE) photodetectors have been investigated. The photodetectors were formed by integrating the active absorption region into a resonant cavity composed of top and bottom (buried) mirrors. A general expression for quantum efficiency 7 for RCE photodetectors was derived taking the external losses into account. Drastic enhancement in 11 is demonstrated at resonant wavelengths for a high quality factor Q cavity with a very thin absorption layer. An improvement by a factor of 4 in the bandwidth-efficiency product for RCE p-in detectors is predicted. Device parameters for achieving very high 7 (> 0.99) without very thick absorption layers and any antireflection coating was discussed. Molecular beam epitaxially grown RCE-heterojunction phototransistors (RCE-HPT) were fabricated and measured demonstrating good agreement of the experiment and the theory. The wavelength selectivity of RCE detection was applied to wavelength demultiplexing. Crosstalk attenuation and efficiency-crosstalk product were calculated for various device parameters. Such a wavelength demultiplexing device was demonstrated by monolithically integrating three RCE-HPT's tuned at different wavelengths. The crosstalk attenuation was 12 dB.
Sensors and Actuators B-Chemical, 2013
We present theory and simulation of a mid-infrared ( = 3.2 m) chalcogenide waveguide monolithically integrated with an evanescently coupled PbTe photodetector for lab-on-a-chip sensing applications. A spacer layer is used to modify effective index of the structure, enabling a waveguide-detector mode to propagate in the chalcogenide waveguide and be absorbed in the PbTe detector. The relation between quantum efficiency and detector dimensions is analyzed showing that the design geometry can be optimized to maximize signal to noise ratio. In addition, the location of metal contacts is optimized to minimize loss while maintaining good device performance. The design is compatible with standard planar lithographic processing and its flexibility suggests multiple applications in the fields of biological and chemical sensing.
Quantum Efficiency Enhancement of Mid Infrared Photodetectors with Photon Trapping Micro-Structures
2018 IEEE Photonics Society Summer Topical Meeting Series (SUM), 2018
The study proposes to use the photon trapping micro-structures to enhance quantum efficiency of the mid infrared photodetectors. The nanostructure that is consist of micro holes reduces reflection and bends the near normally incident light into the lateral modes in the absorbing layer. Summery The recent study show interest in mid infrared photodetectors (MID) for room temperature [1,2]. The new 2D materials such a b-AsP or graphene can show significant absorption for infrared wavelength. Our study proposes the photon trapping nanostructure that enhances performance of the traditional HgCdTe [3] photodetectors as well enhance the coupling of the infrared radiation with the new 2D materials. Recent theoretical and experimental studies [4] showed that micro-holes nanostructures enhanced quantum efficiency (QE) for fast Si photodetectors for data communication. We optimized the micro hole parameters for the MID. Our simulations show that the QE can be increased and the operation region can be widened toward the region where the absorption of the material is relatively small. The QE enhancement also can increase the MID performance at high temperature.
InAsSb∕GaSb heterostructure based mid-wavelength-infrared detector for high temperature operation
Applied Physics Letters, 2007
The properties of a mid infrared photodetector, based on a lattice matched n-N InAs 0.91 Sb 0.09 /GaSb type II heterostructure, were investigated. The relatively simple two layer structure shows very promising characteristics for sensitive and dual color infrared detection. I-V characteristics and spectral response were measured at the temperature range of 10K to 300K. High zero resistance of 2.5 Ω·cm 2 was obtained at room temperature. Detectivity corresponding to InAsSb absorption was measured to be 1.3·10 10 and 4.9·10 9 cm·Hz 1/2 W -1 at 180K and 300K, respectively. An enhanced optical response with gain larger than unity was observed below 120K. Bias tunable dual color detection was demonstrated at all measured temperatures.
Upmost efficiency, few-micron-sized midwave infrared HgCdTe photodetectors
Applied Optics, 2019
Resonant cavity-assisted enhancement of optical absorption was a photodetector designing concept emerged about two and half decades ago, which responded to the challenge of thinning the photoactive layer while outperforming the efficiency of the monolithic photodetector. However, for many relevant materials, meeting that challenge with such a design requires unrealistically many layer deposition steps, so that the efficiency at goal hardly becomes attainable because of inevitable fabrication faults. Under this circumstance, we suggest a new approach for designing photodetectors with absorber layer as thin as that in respective resonant cavity enhanced ones, but concurrently, the overall detector thickness being much thinner, and topmost performing. The proposed structures also contain the cavity-absorber arrangement but enclose the cavity by two dielectric one-dimensional grating-on-layer structures with the same grating pitch, instead of the distributed Bragg reflectors typical of the resonant cavity enhancement approach. By design based on the in-house software, the theoretical feasibility of such ∼ 7.0µm − 8.5µm thick structures with ∼ 100% efficiency for a linearly polarized (TE or TM) mid-infrared range radiation is demonstrated. Moreover, the tolerances of the designed structures' performance against the gratings' fabrication errors are tested, and fair manufacturing tolerance while still maintaining high peak efficiency along with a small deviation of its spectral position off initially predefined central-design wavelength is proved. In addition, the electromagnetic fields amplitudes and Poynting verctor over the cavity-absorber area are visualized. As a result, it is inferred that the electromagnetic fields' confinement in the designed structure, which is a key to their upmost efficiency, is two-dimensional combining in-depth vertical resonant-cavity like confinement, with the lateral microcavity like one set by the presence of gratings.
Resonant Cavity Enhanced Photodiodes in the Short-Wave Infrared for Spectroscopic Detection
IEEE Photonics Technology Letters, 2020
The design, fabrication and characterization of resonant cavity enhanced photodiodes for the shortwave infrared has been investigated. An InGaAsSb absorber and AlGaSb barrier were used in an nBn structure, within a Fabry-Perot cavity bounded by AlAsSb/GaSb DBR mirrors. The resonant cavity design produced a narrow response at 2.25 µm, with a FWHM of ∼ 26 nm and peak responsivity of 0.9 A/W. The photodiodes exhibited high specific detectivities and low leakage currents at 300 K-5 × 10 10 cmHz 1/2 W −1 and 0.2 mAcm −2 respectively, with an applied bias voltage of −100 mV. A maximum specific detectivity of 1 × 10 11 cmHz 1/2 W −1 was achieved at 275 K and the detector continued to perform well at high temperatures-at 350 K the peak specific detectivity was 3×10 9 cmHz 1/2 W −1. The narrow resonant response of these detectors make them suitable for spectroscopic sensing, demonstrated by measurements of glucose concentrations in water. Concentrations as low as 1 % were discriminated, limited only by the associated electronic systems.