Design and Modeling of High-Performance DBR-Based Resonant-Cavity-Enhanced GeSn Photodetector for Fiber-Optic Telecommunication Networks
15 Apr 2021-IEEE Sensors Journal (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 21, Iss: 8, pp 9900-9908
TL;DR: In this article, a distributed Bragg reflector (DBR)-based resonant-cavity-enhanced (RCE) GeSn photodetector on Si substrates was proposed to achieve high-performance photoderetection in terms of responsivity and 3-dB bandwidth for the short-wave infrared (SWIR) high-speed applications.
Abstract: In this work, we present a novel distributed Bragg reflector (DBR)-based resonant-cavity-enhanced (RCE) GeSn photodetector on Si substrates to achieve high-performance photodetection in terms of responsivity and 3-dB bandwidth (BW) for the short-wave infrared (SWIR) high-speed applications. The proposed structure consists of Si/SiO2 distributed Bragg reflectors (DBRs) to enhance the performance of the device. The top and bottom DBRs create a high-quality ( ${Q}$ ) optical cavity to enable multiple pass reflection schemes to increase the responsivity and also high wavelength selectivity with a sharp response. In addition, with an increase in Sn concentration in the active ( i- GeSn) layer, the photodetection range extends to longer wavelengths due to the shrinkage of bandgap energy. The calculated result shows an enhanced 3-dB BW and responsivity as compared to the existing p-i-n PDs. Therefore, the proposed DBR-based RCE GeSn PD can be a promising device for high-speed SWIR photodetection applications.
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TL;DR: In this paper , the authors presented the theory and simulation of heterojunction p-i-n MIR photodetectors (PDs) with Ge0.87Sn0.13/Ge0.92Sn 0.09 layer to elongate the photoabsorption path in the MIR spectrum.
Abstract: Silicon (Si)-based mid-infrared (MIR) photonics has promising potential for realizing next-generation ultra-compact spectroscopic systems for various applications such as label-free and damage-free gas sensing, medical diagnosis, and defense. The epitaxial growth of Ge1-xSnx alloy on Si substrate provides the promising technique to extend the cut-off wavelength of Si photonics to MIR range by Sn alloying. Here, we present the theory and simulation of heterojunction p-i-n MIR photodetectors (PDs) with Ge0.87Sn0.13/Ge0.92Sn0.08 quantum-wells with an additional Ge0.91Sn0.09 layer to elongate the photoabsorption path in the MIR spectrum. The incorporation of QW pairs (N) enables the light-matter interaction due to the carrier and optical confinement in the active region. As a result, the spectral response of the device is enhanced in the MIR range. Devices with varying N were compared in terms of various figure-of merits including dark-current, a photocurrent-to-dark current ratio, detectivity, spectral responsivity, and noise equivalent power (NEP). Additionally, parasitic capacitance-dependent RC and 3dB bandwidth were also studied using a small-signal equivalent circuit model. The proposed device exhibited the extended photodetection wavelength at ∼ 3370 nm and [Formula: see text] up to ∼ 7.3×103 with a dark current of ∼ 56.3 nA for N=8 at 300 K. At a bias of -3V, the proposed device achieved the spectral responsivity of 0.86 A/W at 2870 nm and 0.55 A/W at 3300 nm, detectivity more than 2.5×109 Jones and a NEP less than 2.1×10-13 WHz-0.5 for N=8 at 3250 nm. The calculated 3dB bandwidth of 47.8 GHz, the signal-to-noise ratio (SNR), and linear dynamic range (LDR) of 93 dB and 74 dB were achieved at 3300 nm for N=8 . Thus, these results indicate that the proposed GeSn-based QW p-i-n PDs pave the pathway towards the realization of new and high-performance detectors for sensing in the MIR regime.
11 citations
TL;DR: In this article , the authors presented a comprehensive theoretical study of GeSn vertical p-i-n homojunction waveguide photodetectors (WGPDs) that have a strain-free and defect-free GeSn active layer for 2 µm Si-based EPICs.
Abstract: Silicon photonics is emerging as a competitive platform for electronic–photonic integrated circuits (EPICs) in the 2 µm wavelength band where GeSn photodetectors (PDs) have proven to be efficient PDs. In this paper, we present a comprehensive theoretical study of GeSn vertical p–i–n homojunction waveguide photodetectors (WGPDs) that have a strain-free and defect-free GeSn active layer for 2 µm Si-based EPICs. The use of a narrow-gap GeSn alloy as the active layer can fully cover entire the 2 µm wavelength band. The waveguide structure allows for decoupling the photon-absorbing path and the carrier collection path, thereby allowing for the simultaneous achievement of high-responsivity and high-bandwidth (BW) operation at the 2 µm wavelength band. We present the theoretical models to calculate the carrier saturation velocities, optical absorption coefficient, responsivity, 3-dB bandwidth, zero-bias resistance, and detectivity, and optimize this device structure to achieve highest performance at the 2 µm wavelength band. The results indicate that the performance of the GeSn WGPD has a strong dependence on the Sn composition and geometric parameters. The optimally designed GeSn WGPD with a 10% Sn concentration can give responsivity of 1.55 A/W, detectivity of 6.12 × 1010 cmHz½W−1 at 2 µm wavelength, and ~97 GHz BW. Therefore, this optimally designed GeSn WGPD is a potential candidate for silicon photonic EPICs offering high-speed optical communications.
5 citations
TL;DR: In this paper , the authors demonstrate a deep survey of the strain-controlling mechanisms in GeSn nanomaterials with different methodologies, using either layer configurations, Sn incorporation, or by external stressors, the emission of different photonic and nanoelectronic applications is controlled.
Abstract: Heterostructures based on the GeSn nanocompound have high impact on integrated photonics devices. The promising feature of GeSn nanostructures is its direct bandgap transition that is a result of Sn incorporation in the Ge networks, forming a strained structure. Herein, we demonstrate a deep survey of the strain-controlling mechanisms in GeSn nanomaterials with different methodologies. Using either layer configurations, Sn incorporation, or by external stressors, the emission of different photonic and nanoelectronic applications is controlled. We find that strain engineering modulates the bandgap of GeSn active media to control the region of emission for light emitting diodes, lasing applications, and spectral response for photodetection applications within the mid-IR region of the spectrum and enhances the performance of MOSFETs. This gives GeSn nanocompounds the chance to contribute greatly to IoT physical devices and compete with unstable perovskite materials since GeSn materials can achieve a stable and more reliable performance.
3 citations
TL;DR: In this article , a photonic heterostructure composed of silicon carbide (SiC) layer/germanium (Ge) cavity/distributed Bragg reflector (DBR) has been proposed.
Abstract: 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 ds = 0.75 μm, dg = 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.
2 citations
TL;DR: In this article , the authors report the unique photodetection properties of germanium (Ge) metal-semiconductor-metal (MSM) photoder with Ge micropillar array.
Abstract: Improving detection efficiency of Ge photodetector near the absorptance edge is crucial for fiber-optic telecommunication. Here, we report the unique photodetection properties of germanium (Ge) metal–semiconductor–metal (MSM) photodetector with Ge micropillar array. The responsivity and detectivity of the device at 1550 and 1990 nm are studied. When compared with the Ge photodetector without micropillar, the responsivity and detectivity of micropillar Ge device are improved by 2.76 and 4.21 times at 1550 nm, respectively. This phenomenon is mainly associated with the enhanced absorption efficiency by geometrical light trapping effect and guided modes supported in the micropillar array. Particularly, the values of responsivity and detectivity in the device with Ge micropillar array are enhanced over 29.9 and 37.1 times at 1990 nm than the results in the device without micropillar, which are quite larger than the values at 1550 nm. This feature is related to that the suitable position of absorption enhancement caused by the micropillar array, which can result in the efficiently separation and suppressed recombination of photogenerated carriers under bias voltage. This work provides a feasible approach to broaden the detection wavelength of Ge-based photodetectors, enhance the absorption near the absorption edge, and improve the detection performance.
1 citations
References
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TL;DR: In this paper, a vertical cavity employing a buried oxide layer and a deposited SiO2 top layer as reflectors is developed for enhancing the electroluminescence in the group-IV active layer.
Abstract: An efficient electrically injected group-IV light source compatible with the complementary metal-oxide-semiconductor (CMOS) process is the holy grail for realizing functional, intelligent electronic-photonic integrated circuits for a wide range of applications. The group-IV GeSn material is considered as a promising solution for efficient light sources because its bandgap can be fundamentally transformed from indirect to direct with appropriate Sn compositions. However, an important challenge in realizing efficient electrically injected light emitters is the incorporation of an optical cavity with electrical structures. Here we demonstrate, to the best of our knowledge, the first electrically injected GeSn vertical-cavity surface emitter on the silicon-on-insulator platform. A vertical cavity employing a buried oxide layer and a deposited SiO2 top layer as reflectors is developed for enhancing the electroluminescence in the GeSn active layer. Room-temperature electroluminescence experiments reveal clear c...
40 citations
TL;DR: In this article, a series of strained-layer Ge1−xSnx/Ge superlattices with various Sn contents up to a threshold value that affords a direct bandgap is achieved by the technique of low temperature growth using molecular beam epitaxy.
Abstract: We report an investigation on low dimensional Ge1−xSnx/Ge heterostructures. A series of strained-layer Ge1−xSnx/Ge superlattices with various Sn contents up to a threshold value that affords a direct bandgap is achieved by the technique of low temperature growth using molecular beam epitaxy. The Sn composition, strain status, and crystallographic are systematically characterized by cross-sectional transmission electron microscope and x-ray diffraction. Optical absorption measurements were carried out at room temperature to determine the bandgap energies of the Ge1−xSnx/Ge superlattices. Analyzing the direct transition energies reveals the room-temperature quantum confinement in the Ge1−xSnx/Ge superlattices. Present investigation demonstrates the growth and the quantum confinement of Ge1−xSnx/Ge superlattices, moving an important step forward toward the development of high-performance photonic devices based on Sn-containing group-IV low-dimensional structures.
33 citations
TL;DR: In this article, Resonant cavity enhanced (RCE) photodiodes were fabricated by bonding on a SOI wafer and a broad peak around 1.55-mu m wavelength was observed with higher peak intensity for the 10-layer MQW which had less defects than the 20-layer sample.
26 citations
TL;DR: In this paper, a germanium-tin multiple quantum well (Ge0.9Sn0.1 MQW)-on-Si avalanche photodiode (APD) was proposed for light detection near the 2 μm wavelength range.
Abstract: We report the demonstration of a germanium-tin multiple quantum well (Ge0.9Sn0.1 MQW)-on-Si avalanche photodiode (APD) for light detection near the 2 μm wavelength range. The measured spectral response covers wavelengths from 1510 to 2003 nm. An optical responsivity of 0.33 A W−1 is achieved at 2003 nm due to the internal avalanche gain. In addition, a thermal coefficient of breakdown voltage is extracted to be 0.053% K−1 based on the temperature-dependent dark current measurement. As compared to the traditional 2 μm wavelength APDs, the Si-based APD is promising for its small excess noise factor, less stringent demand on temperature stability, and its compatibility with silicon technology.
25 citations
TL;DR: The design, growth, and characterization of GeSn MSM PDs that are suitable for photonic integrated circuits are presented and it is shown that the spectral responsivity increases with an increase in bias voltage caused by the high electric field, which enhances the carrier generation rate and the carrier collection efficiency.
Abstract: Metal-semiconductor-metal photodetectors (MSM PDs) are effective for monolithic integration with other optical components of the photonic circuits because of the planar fabrication technique. In this article, we present the design, growth, and characterization of GeSn MSM PDs that are suitable for photonic integrated circuits. The introduction of 4% Sn in the GeSn active region also reduces the direct bandgap and shows a redshift in the optical responsivity spectra, which can extend up to 1800 nm wavelength, which means it can cover the entire telecommunication bands. The spectral responsivity increases with an increase in bias voltage caused by the high electric field, which enhances the carrier generation rate and the carrier collection efficiency. Therefore, the GeSn MSM PDs can be a suitable device for a wide range of short-wave infrared (SWIR) applications.
24 citations