Monolithically integrated, resonant-cavity-enhanced dual-band mid-infrared photodetector on silicon (original) (raw)
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Resonant-cavity-enhanced mid-infrared photodetector on a silicon platform
Optics Express, 2010
In this paper, we demonstrate high optical quantum efficiency (90%) resonant-cavity-enhanced mid-infrared photodetectors fabricated monolithically on a silicon platform. High quality photoconductive polycrystalline PbTe film is thermally evaporated, oxygen-sensitized at room temperature and acts as the infrared absorber. The cavity-enhanced detector operates in the critical coupling regime and shows a peak responsivity of 100 V/W at the resonant wavelength of 3.5 µm, 13.4 times higher compared to blanket PbTe film of the same thickness. Detectivity as high as 0.72 × 10 9 cmHz 1/2 W −1 has been measured, comparable with commercial polycrystalline mid-infrared photodetectors. As low temperature processing (< 160 °C) is implemented in the entire fabrication process, our detector is promising for monolithic integration with Si readout integrated circuits.
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.
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).
All‐Silicon Double‐Cavity Fourier‐Transform Infrared Spectrometer On‐Chip
Advanced Materials Technologies, 2019
compact and low-cost form enables a paradigm shift in the analytical chemistry, because the spectrometer in this case goes to the sample anywhere. [14-19] Having the spectrometry affordable and accessible can enable every person to have his own spectrometer in a smartphone or a wearable device. [20-23] Therefore, a tremendous effort is being exerted into this direction. The most recent microscale spectrometers reported in literature have shown different realizations using folded metasurface, [24] photonic crystal slabs, [25] and holographic planar optics. [26] However, these are operating in the visible/near-infrared (NIR) region with very limited spectral range hindering their practical use. This limited range is the main challenge as well facing the spectrometer realization based on the silicon photonics technology. [27] In addition, operating in the visible range means the device is detecting the very weak second overtones of the transition of the molecular vibrations. [28] The diffraction grating microspectrometer introduced in refs [29,30] is characterized by a reasonable spectral range in the NIR but it is not compact enough as the high resolution and compact size constraints cannot be met simultaneously in this architecture. Tunable filter spectrometers have been proposed in refs. [31-33] with good spectral resolution but again limited spectral range. Alternatively, linear variable filter (LVF) spectrometers have been reported [34,35] but the discrete nature of the LVF compromise the scalability of the solution. Fourier Transform InfraRed spectrometers have the advantage of wide spectral range using a single photodetector, good resolution, and high sensitivity due to the multiplex advantage. [36] It has been reported using a Michelson interferometer with inplane mirror, oriented with respect to the substrate, in ref. [37] or out-of-plane mirror in ref. [38]. The assembly of different microcomponents has been reported in refs [17,39] to realize the interferometer, while monolithic integration has been reported in refs. [14,40-43]. Highly reflective micromirrors have been achieved by thin-film metallic coating of the vertically etched surfaces through a shadow mask to keep the beam splitter protected. [44] This usually complicates the fabrication process and compromises the compactness of the spectrometer. In this work, a Fourier transform spectrometer is presented based on cascading monolithically integrated low-finesse optical cavities, or interferometers as shown in Figure 1. [45,46]
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.
Mid-Infrared Tunable Resonant Cavity Enhanced Detectors
Sensors, 2008
Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED) principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 µm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 µm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA).
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.
Applied Physics Letters, 2006
A p-type Si homojunction detector responding in both near-and very-long-wavelength-infrared ͑NIR and VLWIR͒ ranges is demonstrated. The detector consists of a p ++-Si top contact layer, a p +-Si emitter, an undoped Si barrier, and a p ++-Si bottom contact layer grown on a Si substrate. Interband and intraband transitions lead to NIR and VLWIR responses, respectively. The responsivity, quantum efficiency, and detectivity at −1 V bias and 4.6 K are ϳ0.024 A / W, 3.7%, and ϳ1.7ϫ 10 9 cm Hz 1/2 / W at 0.8 m, while they are 1.8 A / W, 8.8%, and ϳ1.2 ϫ 10 11 cm Hz 1/2 / W at 25 m, respectively. The background limited infrared performance temperature at ±0.9 V bias is 25 K.
ACS Sensors, 2016
Mid-infrared spectroscopic techniques rely on the specic "ngerprint" absorption lines of molecules in the mid-infrared band to detect the presence and concentration of these molecules. Despite being very sensitive and selective, bulky and expensive equipment such as cooled mid-infrared detectors are required for conventional systems. In this paper, we demonstrate a miniature CMOS-compatible Silicon-on-Insulator (SOI) photothermal transducer for mid-infrared spectroscopy which can potentially be made in high volumes and at a low cost. The optical absorption of an analyte in the midinfrared wavelength range (3.25 − 3.6µm) is thermally transduced to an optical transmission change of a micro-ring resonator through the thermo-optic eect in silicon. The photothermal signal is further enhanced by locally removing the silicon substrate beneath the transducer, hereby increasing the eective thermal isolation by a factor 1