Photodetectors Research Articles

Silica-Based Hybrid-Integrated Receiver Optical Subassembly for 400 Gbps Ethernet

A silica-based hybrid-integrated receiver optical subassembly (ROSA) for 400 Gbps Ethernet (400GbE) is demonstrated, which consists of an 8-channel silica-based arrayed waveguide grating (AWG), two 4-channel InP-based surface-illuminated photodetector (PD) arrays, two 4-channel transimpedance amplifier (TIA) arrays, and a high-frequency flexible printed circuit (FPC). All lanes of the ROSA exhibit responsivities of over 0.539 A/W, 3-dB bandwidths of greater than 30.86 GHz, and receiver sensitivities of less than −11.7 dBm. The ROSA has achieved a transmission rate of 8 × 50 Gbps for data center interconnect.

Miniaturized computational spectrometer based on two-photon absorption

On-chip spectrometers hold significant promise in the development of laboratory-on-a-chip applications. However, the spectrometers usually require extra on-chip or off-chip photodetectors (PDs) to sense optical signals, resulting in increased footprints and costs. In this paper, we address this issue by proposing a fully on-chip spectrometer based on two-photon absorption (TPA) in a simple micro-ring resonator (MRR) configuration. While TPA is a commonly undesired phenomenon in conventional silicon devices due to its attached absorption losses and nonlinearity, we exploit it as a powerful and efficient tool for encoding spectral information, instead of using additional PDs. The input spectrum can be reconstructed from the sensed TPA current. Our proposed spectrometer achieves a bandwidth of 10 nm with a resolution of 0.4 nm while occupying a small footprint of only 16×16µm2, and the bandwidth can be further improved through several cascaded MRRs. This advancement could enable forward fully integrated and miniaturized spectrometers with low cost, which holds far-reaching applications in in situ biochemical analysis, remote sensing, and intelligent healthcare.

Achieving Low Cost and High Performance Flexible CsPbIBr2 Perovskite Photodetectors Arrays with Imaging System via Dual Interfacial Optimization and Structural Design

AbstractAll‐inorganic metal halide perovskites are competitive candidate as next‐generation flexible photodetectors (PDs) materials due to the remarkable photoelectric properties, enhanced heat stability, and mechanical flexibility. However, constructing low‐cost flexible perovskites PDs with high photodetection performance, good operation stability and mechanical robustness, and manufacturing corresponding flexible PDs array have been a challenge. Herein, the PbCl2 and Zinc(II) Dibenzyldithiocarbamate (Zn(DBDTC)2) are employed to modify bottom and top interface of CsPbIBr2 perovskite layer, respectively, to passivate surface trap state, enhance hydrophobicity and resist phase segregation, and improve interface contact. Consequently, the self‐powered champion PDs with low‐cost Bi2Te3 electrode reach a responsivity of 0.38 A W−1 and a maximum detectivity of 3.44 × 1013 Jones at 570 nm, and maintain the outstanding long‐term and operational stability without additional encapsulation. Meanwhile, the HTL‐free flexible PDs based on low‐temperature CsPbIBr2 perovskite layer exhibit impressive photodetection performance and mechanical robustness in bending test. More importantly, the flexible PDs array (5 × 5 pixels) and corresponding imaging system are fabricated with uniform and clear imaging results under flatting and bending state. This research is of great significance for the application of stable and high‐performance inorganic perovskites PDs and flexible array imaging systems.

Tuning the Optoelectronic Properties of Pulsed Laser Deposited “3D”‐MoS2 Films via the Degree of Vertical Alignment of Their Constituting Layers

AbstractPulsed‐laser‐deposition (PLD) is used to deposit MoS2 thin films at substrate temperatures (Td) ranging from 25 to 700 °C. A Td = 500 °C is identified as the optimal temperature that yields MoS2 films consisting of highly‐crystallized 2H‐MoS2 phase with a strong (002) preferential orientation, a direct optical bandgap (Eg) of ∼1.4 eV and a strong photoresponse of ∼1500%. Raman spectroscopy revealed that the degree of vertical alignment of MoS2 layers in the films also reaches its maximum at Td = 500 °C. High‐resolution‐transmission‐electron‐microscopy has provided a clear‐cut evidence that the PLD‐MoS2 films predominantly consist of vertically aligned MoS2 layers over all the film thickness of ∼90 nm, enabling those “3D” films to behave as a direct‐bandgap “2D‐MoS2” with exceptional optoelectronic properties. Indeed, at Td = 500 °C, the PLD‐MoS2 based photodetectors (PDs) devices are shown to exhibit the highest responsivity (R) and detectivity (D*) values (125 mA W−1 and 9.2 × 109 Jones, respectively) ever reported for large area (≥ 1 cm2) MoS2‐based PDs operating at a voltage as low as 1 V. For the first time, a constant‐plus‐linear relationship between Eg, R, and D* of the PDs and the degree of vertical alignment of the MoS2 layers is established. Such a correlation is fundamental for the controlled growth of PLD‐MoS2 films and the tuning of their properties in view of their integration with standard large‐scale‐integration processing.

Vacuum-ultraviolet (λ < 200 nm) photodetector array

The vacuum-ultraviolet (VUV, 10–200 nm) imaging photodetector (PD) based on the wide bandgap semiconductor (WBGS) can realize a more detailed observation of solar storms than the silicon ones. Here, an 8 × 8 VUV PD array based on the semiconductor AlN with an ultra-wide bandgap is presented, exhibiting the shortest cutoff wavelength (203 nm) reported so far. The PD array with a Pt/AlN/SiC/Ti/Au photovoltaic structure shows an excellent selective response to VUV light, an extremely low dark current density of 2.85 × 10–11 A·cm−2@ -2 V, a responsivity of 0.054 A·W−1@ 0 V and an ultra-short rise time of 13 ns. Also, the clear boundaries and an obvious contrast between light and dark of the VUV image displayed in the imaging measurement indicate the good imaging ability of this PD array, which can be used for the imaging application with high signal-to-noise ratio and high response speed. These results provide rich experience for the development of VUV imaging PDs based on WBGSs both in their fabrication and the practical applications in VUV detection.

Unveiling the contribution of piezoelectric and ferroelectric effect to inorganic halide perovskites photodetectors

Compression and tensile strain based on piezo-phototronic effect represent a valid method for modulating the photocurrent of photodetectors. However, the underlying mechanism responsible for the asymmetric increase/decrease of photocurrent under identical compressive/tensile stresses remains unclear. Herein, a PVDF/CsPbBr3 composite fiber incorporating orthorhombic CsPbBr3 (a piezoelectric phase) is fabricated through room-temperature electrospinning. Subsequently, flexible photodetectors (PDs) based on PVDF/CsPbBr3 are constructed to explore the impact of strain on photocurrent. The results reveal a 103% increase in photocurrent under a strain of −0.09% (compressive strain), significantly exceeding the 38% decrease observed under a strain of 0.09% (tensile strain). Furthermore, the piezoelectric and ferroelectric properties of the orthorhombic CsPbBr3 are computed using density functional theory (DFT), confirming that the asymmetric modulation of photocurrent stems from the nature of the piezoelectric effect and ferroelectric effect. Additionally, the ferroelectric effect exerts a more pronounced influence on the photocurrent, which is 2.2 times greater than the piezoelectric effect. This work provides compelling evidence for the piezoelectric and ferroelectric effects of inorganic halide perovskites, underscoring the substantial potential of these effects in optoelectronic devices.

Facile sulfur-assisted synthesis of GaAs nanowires /si heterojunctions for broadband self-powered photodetector

Nanowires (NWs)-based heterojunction photodetectors (PDs) have been widely applied in the fields of remote sensing, night vision, environmental monitoring, and optical communications with high light absorption coefficient and photoelectric conversion efficiency. Here, S-GaAs NWs/Si heterojunction was developed to form a broadband self-powered PDs by growing GaAs NWs on Si substrate through the sulfur-catalyzed assisted chemical vapor deposition (CVD) technology. Compared with the pure GaAs NWs, the sulfur-assisted catalysts could not only inhibit Ostwald ripening of Au seeds to improve the crystalline quality of NWs but also form a thin Ga–S bond passivation layer to reduce surface defects and enhance the optoelectronic performance of the PDs. The fabricated GaAs NWs/Si heterojunction PDs exhibit excellent performances with the large responsivity of 10.3 mA W−1 and high detectivity of 9.59 × 1012 cm Hz1/2 W−1. Additionally, the designed PDs have the broadband wavelength photoresponse from visible to near infrared and fast response speed (rise/fall time of 3.8/21.8 ms). Importantly, the develop strategy of hybrid heterojunction PDs can be extended to other semiconductor materials for facilitating the practical application of high-performance optoelectronic devices.

Unveiling the potentiality of a self-powered CGT chalcopyrite-based photodetector: theoretical insights

The article demonstrates the design and modelling of CuGaTe2 direct bandgap (1.18 eV) chalcopyrite-based photodetector (PD), which has superb optical and electronic characteristics and shows remarkable performance on the photodetector. The photodetector has been investigated throughout the work by switching width, carrier and defect densities of particular layers and also the interface defect density of particular interfaces. The various layers have been optimized for the higher performance of the PD. Also, the impression of various device resistances has been analyzed. The JSC and VOC of the heterostructure photodetector is found to be 38.27 mA/cm2 and 0.94 V, in turn. The maximum responsivity, R and detectivity, D* are found to be 0.663A/W and 1.367 × 1016 Jones at a wavelength of 920 nm. The spectral response has a very high value in the range of 800 to 1000 nm light wavelength, which confirmed that this device is capable of detecting the near infrared (NIR) region of light. This work gives important guidance for the manufacture of CGT material-based photodetectors with higher performance.

High-performance photoelectrochemical (PEC) type self-powered ultraviolet photodetectors (PDs) based on three-dimensional ZnO film/carbon fiber paper

Novel photoelectrochemical ultraviolet detection technologies based on semiconductor/electrolyte heterojunctions have attracted significant attention due to their cost-effective fabrication and self-powered characteristic. In this study, ZnO films were deposited on three-dimensional carbon fiber paper (3D CFP) using a one-step sputtering method, resulting in the preparation of 3D ZnO/CFP composites as photoanodes for photoelectrochemical (PEC) type photodetectors (PDs). The fabricated device demonstrates outstanding photoelectrochemical performance, showcasing a remarkable responsivity of approximately 31.76 mA/W, a detectivity of 3.06 × 1012 jones, and a rapid photoresponse time of 76.51/48.51 ms. Furthermore, the device exhibits exceptional photoresponse stability during cycling tests. The unique structure of 3D CFP, composed of intertwined carbon fiber in three dimensions, offers an enlarged specific surface area and efficient carrier transport pathways for the photoanode in self-powered PEC-PDs. This characteristic facilitates effective electrolyte diffusion throughout the entire film, as well as efficient transport of photo-generated charge carriers, thereby significantly enhancing the overall performance of the PEC-PDs. This study affirms the effectiveness of the synergistic interaction between 3D CFP and ZnO film for advanced UV photodetectors, demonstrating both mass production viability and promise for the future of photoelectrochemical detection technology.

MoS2 based flexible photodetector for broadband visible light photodetection

In recent years, flexible photodetectors (PD) have emerged as a significant innovation with potential applications in healthcare, security, and environmental monitoring. Two-dimensional (2D) layers of metal dichalcogenides MoS2 have gathered significant attention due to their ultrathin thickness and promising applications in the fields of flexible PD. 2H phase of MoS2 micro-flowers were synthesized by facile hydrothermal route. Raman spectra was employed to analyze the quality of grown MoS2 and confirmed with E12g and A1g Raman phonon modes. The micro-flower morphological was verified through FESEM. Subsequently, PD device was fabricated through bar coating method over a flexible polyethylene terephthalate (PET) substrate and Indium Tin oxide (ITO) was employed as an electrode. Photodetection property of the device was tested under dark and illumination. MoS2-microflower PD exhibit good photoresponsivity and detectivity of 1.5 µA/W and 105 Jones at 5 V respectively. Moreover, detector demonstrated remarkable flexibility and exceptional air stability.

Photoresponse Enhancement in MAPbI3/Si Heterojunction Through P(VDF‐TrFE) Doping and Introducing Pyro‐Phototronic Effect

AbstractThe photovoltaic effect and pyro‐phototronic effect offer a promising approach to enhance self‐powered photodetectors (PDs) performance. However, further investigation is warranted to explore the performance improvement, the impact of pyroelectric effect, and the underlying coupling mechanism. In this study, heterojunction PDs consisting of ITO/CH3NH3(MA)PbI3:P(VDF‐TrFE)/Si are prepared, with P(VDF‐TrFE) concentration varying from 0 to 1 wt.%. The results reveal that the concentration of P(VDF‐TrFE) has a significant impact on the photovoltaic response, with the optimal concentration being 0.8 wt.%. The PD displays a broadband response (405–1064 nm) at zero bias, peaking at 780 nm. Furthermore, the introduction of P(VDF‐TrFE) significantly enhances the responsivity (R) and detectivity (D), resulting in a remarkable increase of 5814%. The values of R and D reach 1.93 × 104 V W−1 and 1.99 × 1012 Jones, respectively. Moreover, the PD demonstrates an ultrafast response time of 81.6/208 µs. Additionally, the pyro‐phototronic effect extends the response wavelength to 1550 nm, surpassing the spectral limit of the heterojunction. Importantly, the heterojunction exhibits improved weak light detection ability. At 6.37 µW cm−2 intensity, R and D show an impressive increase of 21 683%, reaching 8.99 × 104 V W−1 and 9.3 × 1013 Jones, respectively.

High-uniformity and high-performance waveguide Ge photodetectors for the O and C bands.

This paper presents the test results for high-performance and high-uniformity waveguide silicon-based germanium (Ge) photodetectors (PDs) for the O band and C band. Both wafer-scale and chip-scale test results are provided. The fabricated lateral p-i-n (LPIN) PDs exhibit a responsivity of 0.97A/W at a bias of -2V, a bandwidth of 60GHz, and a no-return-to-zero (NRZ) eye diagram rate of 53.125Gb/s. Additionally, an average dark current of 22.4nA was obtained in the vertical p-i-n (VPIN) PDs at -2V by optimizing the doping process. The device can reach an average responsivity of 0.9A/W in the O band. The standard deviation in a wafer with a dark current and responsivity is as low as 7.77nA and 0.03A/W at -2V, respectively.

High-Sensitivity Photoelectrochemical Ultraviolet Photodetector with Stable pH-Universal Adaptability Based on Whole Single-Crystal Integrated Self-Supporting 4H-SiC Nanoarrays.

Emerging photoelectrochemical (PEC) photodetectors (PDs) have notable advantages over conventional PDs and have attracted extensive attention. However, harsh liquid environments, such as those with high corrosivity and attenuation, substantially restrict their widespread application. Moreover, most PEC PDs are constructed by assembling numerous nanostructures on current collector substrates, which inevitably contain abundant interfaces and defects, thus greatly weakening the properties of PDs. To address these challenges, a high-performance pH-universal PEC ultraviolet (UV) PD based on a whole single-crystal integrated self-supporting 4H-SiC nanopore array photoelectrode is constructed, which is fabricated using a two-step anodic oxidation approach. The PD exhibits excellent photodetection behavior, with high responsivity (218.77mAW-1), detectivity (6.64×1013Jones), external quantum efficiency (72.47%), and rapid rise/decay times (17/48ms) under 375nm light illumination with a low intensity of 0.15mWcm-2 and a bias voltage of 0.6V, which is fall in the state-of-the-art of the wide-bandgap semiconductor-based PDs reported thus far. Furthermore, the SiC PEC PD exhibits excellent photoresponse and long-term operational stability in pH-universal liquid environments. The improved photodetection performance of the SiC PEC PD is primarily attributed to the synergistic effect of the nanopore array structure, integrated self-supporting configuration, and single-crystal structure of the whole photoelectrode.

High detectivity Ge photodetector at 940 nm achieved by growing strained-Ge with a top Si stressor.

We have developed a self-powered near-infrared photodetector (PD) with high detectivity using a tensile strained Ge layer capped with a thick Si layer. The Si layer acts as a stressor and maintains the strain of Ge with minimal dislocations by creating a rough surface. By using Raman spectroscopy, we confirmed that the Ge layer has a 1.83% in-plane tensile strain. The Ge PD exhibits a high responsivity of 0.45 A/W at -1 V bias voltage for 940 nm wavelength. The PD's dark current density is as low as ∼1.50 × 10-6 A/cm2 at -1 V. The high responsivity and low dark current result in a detectivity as high as 6.55 × 1011 cmHz1/2/W. This Ge PD has great potential for applications in light detection and ranging (LiDAR), Internet of Things (IoTs), and Optical Sensing Networks.

Research on ultrawideband photodetector module based on parasitic parameter regulation.

A four-channel ultrawideband photodetector (PD) module with a size of 26.1 mm ×33.2 mm × 8.5 mm has been demonstrated in our laboratory. We propose a method to improve the bandwidth of the PD module based on compensating parasitic parameters by dual resistance regulation on the P and N terminals of the PD chip. A small signal equivalent circuit model with package matching network is established for the PD module, and the effectiveness of the proposed method and the accuracy of the model are verified by experiments. A four-channel photodetector module with a -3 dB bandwidth of up to 67 GHz is fabricated by using photodetector chips with -3 dB bandwidths of 46 GHz, and the responsivity is up to 0.50A/W.

MAPbI3 perovskite photodetectors for high-performance optical wireless communication

High-sensitivity and fast-response photodetectors (PDs) are vital part of optical wireless communication (OWC) system. In this work, we develop an organic–inorganic hybrid perovskite material (MAPbI3) based p–i–n structured PD. By optimizing the precursor solution concertation, the PD showed a high responsivity of 0.98 A W−1, a fast response time t rise/t fall of 12/12.5 μs, a specific detectivity of 2.62 × 1013 Jones, and the f−3dB of 24 kHz under the 532 nm laser and −0.2 V bias voltage. Furthermore, we designed an OWC system based on the prepared PD. With the baud rate of 19200 bps, the system exhibits a bit error rate less than 10−6, and it can realize 9.63 m long-distance communication and quick transmission applications such as strings, texts, photos, and audios. Our work demonstrates the great application potential of perovskite PDs in the field of optical communication.

A Self-Calibrated Single Wavelength Biosensor for Measuring Oxygen Saturation.

Traditional methods for measuring blood oxygen use multiple wavelengths, which produce an intrinsic error due to ratiometric measurements. These methods assume that the absorption changes with the wavelength, but in fact the scattering changes as well and cannot be neglected. We found that if one measures in a specific angle around a cylindrical tissue, called the iso-pathlength (IPL) point, the reemitted light intensity is unaffected by the tissue's scattering. Therefore, the absorption can be isolated from the scattering, which allows the extraction of the subject's oxygen saturation. In this work, we designed an optical biosensor for reading the light intensity reemitted from the tissue, using a single light source and multiple photodetectors (PDs), with one of them in the IPL point's location. Using this bio-device, we developed a methodology to extract the arterial oxygen saturation using a single wavelength light source. We proved this method is not dependent on the light source and is applicable to different measurement locations on the body, with an error of 0.5%. Moreover, we tested thirty-eight males and females with the biosensor under normal conditions. Finally, we show the results of measuring subjects in a hypoxic chamber that simulates extreme conditions with low oxygen.

High-performance broadband SnS photodetector based on photoconductive-bolometric coupling effect

Due to its large absorption coefficient and high carrier mobility, SnS exhibits strong promise in the area of optoelectronic devices. Nevertheless, the fabrication of large-area, high-quality films for SnS photodetectors (PDs) with superior photoresponse remains a formidable task, seriously limiting its further practical application. In the present study, we report a superior-performance broadband PD founded on the epitaxial SnS film. Large-area uniform SnS films were grown epitaxially on (100)-oriented KBr using magnetron sputtering technique, further exfoliated, and transferred in a wafer size to fabricated two-ends PD devices. Benefitting from high crystallization and unique photoconductive-bolometric coupling effect, the two modes of operation exhibit a wide range of spectral responses from the visible to near-infrared wavelength (405–1920 nm). Particularly noteworthy is the SnS device fabricated, which demonstrates an impressive responsivity of 95.5 A W−1 and a detectivity of 7.8 × 1011 Jones, outperforming other devices by 1–2 orders of magnitude. In addition, SnS PD shows excellent environmental durability. This work provides a robust approach to develop high-performance broadband SnS PDs, while simultaneously offering deep insight into the light–matter interactions.

Lead-free perovskite Cs2AgBiBr6 photodetector detecting NIR light driven by titanium nitride plasmonic hot holes

Lead-free perovskite Cs2AgBiBr6 manifests great potential in developing high-performance, environmentally friendly, solution-processable photodetectors (PDs). However, due to the relatively large energy bandgap, the spectrum responses of Cs2AgBiBr6 PDs are limited to the ultraviolet and visible region with wavelengths shorter than 560 nm. In this work, a broadband Cs2AgBiBr6 PD covering the ultraviolet, visible, and near infrared (NIR) range is demonstrated by incorporating titanium nitride (TiN) nanoparticles that are prepared with the assistance of self-assembled polystyrene sphere array. In addition, an atomically thick Al2O3 layer is introduced at the interface between the Cs2AgBiBr6 film and TiN nanoparticles to alleviate the dark current deterioration caused by nanoparticle incorporation. As a result, beyond the spectrum range where Cs2AgBiBr6 absorbs light, the external quantum efficiency (EQE) of the TiN nanoparticle incorporated Cs2AgBiBr6 PD is enhanced significantly compared with that of the control, displaying enhancement factors as high as 2000 over a broadband NIR wavelength range. The demonstrated enhancement in EQE arises from the photocurrent contribution of plasmonic hot holes injected from TiN nanoparticles into Cs2AgBiBr6. This work promotes the development of broadband solution-processable perovskite PDs, providing a promising strategy for realizing photodetection in the NIR region.

Poly-Si/a-Si/4H-SiC p-n heterojunction broadband photodetector prepared by magnetron sputtering

With the increasing complexity of scenarios, there is a growing need for broadband photodetectors (PDs). In this work, we report a polycrystalline-Si (poly-Si)/amorphous-Si (a-Si)/4H-SiC p-n heterojunction PD with efficient response in a broad spectral range of ultraviolet–visible–near-infrared. The poly-Si/a-Si/4H-SiC heterojunction was achieved by magnetron sputtering and annealing. The fabricated heterojunction device has a low dark current of 1 pA at −40 V and a fast response time of 3 ns due to the outstanding rectification characteristics of the heterojunction combined with narrow bandgap and wide bandgap material. In addition, the carrier behavior of the heterojunction exposed to broadband light is analyzed in detail by constructing the energy band diagram.