Showing papers on "Photodiode published in 2022"
45 citations
TL;DR: In this paper , an injection-locked heterodyne source based on generic foundry-fabricated photonic integrated circuits (PIC) attached to a uni-traveling carrier photodiode generating high-purity terahertz (THz) carriers is presented.
Abstract: Photonic generation of Terahertz (THz) carriers displays high potential for THz communications with a large tunable range and high modulation bandwidth. While many photonics-based THz generations have recently been demonstrated with discrete bulky components, their practical applications are significantly hindered by the large footprint and high energy consumption. Herein, we present an injection-locked heterodyne source based on generic foundry-fabricated photonic integrated circuits (PIC) attached to a uni-traveling carrier photodiode generating high-purity THz carriers. The generated THz carrier is tunable within the range of 0-1.4 THz, determined by the wavelength spacing between the two monolithically integrated distributed feedback (DFB) lasers. This scheme generates and transmits a 131 Gbits-1 net rate signal over a 10.7-m distance with -24 dBm emitted power at 0.4 THz. This monolithic dual-DFB PIC-based THz generation approach is a significant step towards fully integrated, cost-effective, and energy-efficient THz transmitters.
31 citations
TL;DR: In this article , a mixed-dimensional HgCdTe/black phosphorous van der Waals heterojunction photodiode is proposed for polarization-sensitive midwave infrared photodetection.
Abstract: New-generation infrared detectors call for higher operation temperature and polarization sensitivity. For traditional HgCdTe infrared detectors, the additional polarization optics and cryogenic cooling are necessary to achieve high-performance infrared polarization detection, while they can complicate this system and limit the integration. Here, a mixed-dimensional HgCdTe/black phosphorous van der Waals heterojunction photodiode is proposed for polarization-sensitive midwave infrared photodetection. Benefiting from van der Waals integration, type III broken-gap band alignment heterojunctions are achieved. Anisotropy optical properties of black phosphorous bring polarization sensitivity from visible light to midwave infrared without external optics. Our devices show an outstanding performance at room temperature without applied bias, with peak blackbody detectivity as high as 7.93 × 1010 cm Hz1/2 W−1 and average blackbody detectivity over 2.1 × 1010 cm Hz1/2 W−1 in midwave infrared region. This strategy offers a possible practical solution for next-generation infrared detector with high operation temperature, high performance, and multi-information acquisition.
27 citations
TL;DR: In this paper, a loop reflector-assisted silicon-germanium waveguide avalanche photodiode with improved responsivity is presented. But the performance of the reflector is not improved.
Abstract: We present a loop reflector-assisted silicon-germanium waveguide avalanche photodiode with improved responsivity. Compared to the same APD without the reflector, it has 1.49 times higher responsivity, $\sim$ 1.12 A/W, without compromising the speed performance. It exhibits a 3 dB-bandwidth of $\sim$ 25 GHz, a build-up time limited gain-bandwidth product of $\sim$ 296 GHz, a highest gain-bandwidth product of $\sim$ 497 GHz. Clear eye diagrams are measured at both 32 Gbps NRZ and 64 Gbps PAM4 modulation, and a 1 $\sim$ 2 dB better sensitivity up to −15.7 dBm with 32 Gbps NRZ at a BER of 2.4 $\times 10^{-4}$ .
27 citations
TL;DR: In this article , the authors investigated the temperature-dependent photodetection behavior of a high-performance AlGaN/GaN-based ultraviolet phototransistor (UVPT) operating under 265nm illumination.
Abstract: In this work, we investigated the temperature-dependent photodetection behavior of a high-performance AlGaN/GaN-based ultraviolet phototransistor (UVPT) operating under 265 nm illumination. As the temperature continuously rises from room temperature to 250 °C, the photocurrent of a device increases in the beginning but suffers from degradation afterwards. This can be explained by the competing process between the generation and recombination rate of photo-induced carriers in the UVPT at room and high temperatures. Intriguingly, we found that the optimal operating temperature for our UVPT is around 50 °C, featuring a high peak responsivity of 1.52 × 105 A/W under a light intensity of 45 μW/cm2. Furthermore, the photoresponse time of our UVPT is also highly temperature-dependent, exhibiting the shortest rise time of 50 ms at 100 °C while the decay time is monotonically reduced as the temperature rises to 250 °C. Notably, our AlGaN/GaN-based UVPTs exhibit ultra-high responsivity at high temperatures, which have outperformed those earlier reported UV photodetectors in the form of different device architectures, highlighting the great potential of such device configurations for harsh environment applications.
25 citations
TL;DR: In this article , the authors reviewed the evolution of non-dispersive infrared gas sensing techniques and the basic components of these sensors are discussed one-by-one, and the shortcomings of the NDIR gas sensor have been summarized and the efforts made in recent times to cope with these are also discussed.
Abstract: Non-dispersive infrared gas sensing (NDIR) is a unique optical sensing technique where IR radiation interacts with the targeted analyte and in the process, it is absorbed. This absorption is unique for every gas and hence, based on the absorption characteristics, gas molecules can be fingerprinted and distinctively identified. A simple NDIR gas sensor consists of an IR emitter, detector, optical filter, gas cell, and circuit elements for signal processing. Further, these components also offer choice for selection for example a microelectromechanical system (MEMS) based membrane heater, a light-emitting diode (LED), and IR lamp all have the capability of generating IR spectra. Similarly, a pyroelectric detector, photodiode, bolometer, as well as thermopile has the ability to detect IR rays. The choice of the selection of components carries advantages and disadvantages associated with them, and thus it is very important to choose them correctly for the targeted applications. This article reviews the evolution of non-dispersive infrared gas sensing techniques and the basic components of these sensors are discussed one-by-one. Finally, the shortcomings of the NDIR gas sensor have been summarized and the efforts made in recent times to cope with these are also discussed.
24 citations
TL;DR: In this paper , a review of perovskite photodetectors is presented, focusing on the preparation and photoelectric performance and the effect of noise on the performance and how to reduce the detector noise to increase the detection rate.
Abstract: In recent years, perovskite materials have been widely used in optoelectronic components due to a series of advantages such as a high light absorption coefficient, high carrier mobility, long carrier diffusion length, shallow defect level, and high crystallinity. The photodetector is an important photoelectric device that can convert light radiation signals into electrical signals, so it has significant applications and scientific research value in military, civil, and other fields. Semiconductor materials are an essential part of photodetectors. So far, many semiconductor materials have been used in photodetectors, including silicon, carbon nanotubes, III–V compounds, and quantum dots, and remarkable progress has been made in improving the light detection performance and device structure design. However, photodetectors based on these materials usually require expensive materials, rigorous processes, and complex manufacturing conditions, which hinder their commercial application. Optoelectronic devices based on perovskite materials have the advantages of a simple fabrication process, low cost, and high performance, making them widely considered in optoelectronic applications. This review focuses on the preparation and photoelectric performance of the perovskite photodetector and the effect of noise on the performance of the perovskite detector and how to reduce the detector’s noise to increase the detection rate. In this review, we mainly discuss the following four aspects of work. First, we discuss the various noises of perovskite photodetectors. Then, we explore ways to reduce the noise of perovskite detectors with different structures (photoconductor, photodiode, and phototransistor). We explore corresponding improvement methods for different device structure detectors to reduce noise and improve the detection performance. Next, we discuss the different synthesis methods of all-inorganic perovskites, including solution processing synthesis, vapor-assisted solution synthesis, and chemical vapor deposition. Finally, current challenges of perovskite photodetectors (toxicity, stability, flexibility, and self-powered) are summarized and prospected.
23 citations
TL;DR: The employed vacuum fabrication process and the easy-to-adapt PM-OPD concept enable seamless upscaling of production, paving the way to a commercially relevant photodetector technology.
Abstract: Highly responsive organic photodetectors allow a plethora of applications in fields like imaging, health, security monitoring, etc. Photomultiplication‐type organic photodetectors (PM‐OPDs) are a desirable option due to their internal amplification mechanism. However, for such devices, significant gain and low dark currents are often mutually excluded since large operation voltages often induce high shot noise. Here, a fully vacuum‐processed PM‐OPD is demonstrated using trap‐assisted electron injection in BDP‐OMe:C60 material system. By applying only −1 V, compared with the self‐powered working condition, the responsivity is increased by one order of magnitude, resulting in an outstanding specific detectivity of ≈1013 Jones. Remarkably, the superior detectivity in the near‐infrared region is stable and almost voltage‐independent up to −10 V. Compared with two photovoltaic‐type photodetectors, these PM‐OPDs exhibit the great potential to be easily integrated with state‐of‐the‐art readout electronics in terms of their high responsivity, fast response speed, and bias‐independent specific detectivity. The employed vacuum fabrication process and the easy‐to‐adapt PM‐OPD concept enable seamless upscaling of production, paving the way to a commercially relevant photodetector technology.
23 citations
TL;DR: In this paper, two blends of an ultralow bandgap push-pull polymer TQ-T combined with state-of-the-art non-fullerene acceptors, IEICO-4F and Y6, are compared to obtain OPDs for sensing in the near-infrared (NIR) region.
Abstract: Recent efforts in the field of organic photodetectors (OPD) have been focused on extending broadband detection into the near-infrared (NIR) region. Here, two blends of an ultralow bandgap push-pull polymer TQ-T combined with state-of-the-art non-fullerene acceptors, IEICO-4F and Y6, are compared to obtain OPDs for sensing in the NIR beyond 1100 nm, which is the cut off for benchmark Si photodiodes. It is observed that the TQ-T:IEICO-4F device has a superior IR responsivity (0.03 AW-1 at 1200 nm and -2 V bias) and can detect infrared light up to 1800 nm, while the TQ-T:Y6 blend shows a lower responsivity of 0.01 AW-1 . Device physics analyses are tied with spectroscopic and morphological studies to link the superior performance of TQ-T:IEICO-4F OPD to its faster charge separation as well as more favorable donor-acceptor domains mixing. In the polymer blend with Y6, the formation of large agglomerates that exceed the exciton diffusion length, which leads to high charge recombination, is observed. An application of these devices as biometric sensors for real-time heart rate monitoring via photoplethysmography, utilizing infrared light, is demonstrated.
22 citations
TL;DR: This work provides an innovative approach to realize the secure optoelectronic logic circuit based on nonvolatile van der Waals (vdW) heterostructure phototransistors based on a functionally complete set of logic gates in a reconfigurable manner.
Abstract: With the rising demand for information security, there has been a surge of interest in harnessing the intrinsic physical properties of device for designing a secure logic circuit. Here we provide an innovative approach to realize the secure optoelectronic logic circuit based on nonvolatile van der Waals (vdW) heterostructure phototransistors. The phototransistors comprising WSe2 and h-BN flakes exhibit electrical tunability of nonvolatile conductance under cooperative operations of electrical and light stimulus. This intriguing feature allows the phototransistor to work as a building block for the design of secure optoelectronic logic circuit in which the information encryption can be directly achieved with a designed secret key. On the basis of this approach, we assemble two phototransistors into an optoelectronic hybrid circuit and implement a functionally complete set of logic gates (i.e., NOR, XOR, and NAND) in a reconfigurable manner. Our findings highlight the potential of nonvolatile phototransistors for the development of reconfigurable secure optoelectronic circuits.
22 citations
01 Jan 2022
TL;DR: In this paper , the state-of-the-art technologies of materials and devices in solution-processed organic photodiodes (OPDs) to meet the demands for future high-resolution image sensors, which involves challenges ranging from the absence of a fundamental understanding of OPDs to commercialization requirements.
Abstract: The technology to record image information at high resolution is of great importance in the optical areas of applied physics and biochemical imaging, as well as in commercial imaging applications such as cameras and machine vision. Organic semiconductors are drawing interest as photodetecting materials for next-generation high-resolution image sensors (IS) owing to their excellent properties such as high absorption coefficient, and color tunability and cost-effective manufacturability. These advantages offer the potential to exceed the technical limitation of silicon-based IS. This article reviews the state-of-the-art technologies of materials and devices in solution-processed organic photodiodes (OPDs) to meet the demands for future high-resolution ISs, which involves challenges ranging from the absence of a fundamental understanding of OPDs to commercialization requirements. Further, this article overviews the progress in the industry as well as academic society. The various requirements and technologies for the development of color-filter-free OPDs with narrow-wavelength detection are also discussed. This review concludes with an outlook of advances in these materials and devices to open up new commercialization routes.
TL;DR: In this article, the state-of-the-art technologies of materials and devices in solution-processed organic photodiodes (OPDs) to meet the demands for future high-resolution image sensors, which involves challenges ranging from the absence of a fundamental understanding of OPDs to commercialization requirements.
Abstract: The technology to record image information at high resolution is of great importance in the optical areas of applied physics and biochemical imaging, as well as in commercial imaging applications such as cameras and machine vision. Organic semiconductors are drawing interest as photodetecting materials for next-generation high-resolution image sensors (IS) owing to their excellent properties such as high absorption coefficient, and color tunability and cost-effective manufacturability. These advantages offer the potential to exceed the technical limitation of silicon-based IS. This article reviews the state-of-the-art technologies of materials and devices in solution-processed organic photodiodes (OPDs) to meet the demands for future high-resolution ISs, which involves challenges ranging from the absence of a fundamental understanding of OPDs to commercialization requirements. Further, this article overviews the progress in the industry as well as academic society. The various requirements and technologies for the development of color-filter-free OPDs with narrow-wavelength detection are also discussed. This review concludes with an outlook of advances in these materials and devices to open up new commercialization routes.
TL;DR: In this article, a frequency-modulated continuous-wave light detection and ranging system on a chip was proposed by combining a beam scanner with Ge photodiodes for delay homodyne coherent detection.
Abstract: Photonic crystal slow-light gratings fabricated using Si photonics enable high-speed, high-resolution, and wide field-of-view two-dimensional beam scanning via the thermo-optic effect. In this paper, we built a frequency-modulated continuous-wave light detection and ranging system on a chip by combining a beam scanner with Ge photodiodes for delay homodyne coherent detection. Emitting and scanning frequency-swept laser beam, point cloud images of 154 × 32 = 4928 points were obtained. The real-time operation and velocity imaging were also demonstrated. This device is expected to detect Lambertian targets over long distances in the 100-m class by reasonably reducing chip and optics losses and suppressing internal noise components.
TL;DR: In this paper , scaled and waveguide coupled III-V photodiodes are implemented as InP/In 0.5 Ga 0.1 As/InP p-i-n heterostructures.
Abstract: Abstract The seamless integration of III-V nanostructures on silicon is a long-standing goal and an important step towards integrated optical links. In the present work, we demonstrate scaled and waveguide coupled III-V photodiodes monolithically integrated on Si, implemented as InP/In 0.5 Ga 0.5 As/InP p-i-n heterostructures. The waveguide coupled devices show a dark current down to 0.048 A/cm 2 at −1 V and a responsivity up to 0.2 A/W at −2 V. Using grating couplers centered around 1320 nm, we demonstrate high-speed detection with a cutoff frequency f 3dB exceeding 70 GHz and data reception at 50 GBd with OOK and 4PAM. When operated in forward bias as a light emitting diode, the devices emit light centered at 1550 nm. Furthermore, we also investigate the self-heating of the devices using scanning thermal microscopy and find a temperature increase of only ~15 K during the device operation as emitter, in accordance with thermal simulation results.
TL;DR: In this paper , the authors demonstrate heterogeneously integrated modified uni-traveling carrier photodiodes on LNOI with a record-high bandwidth of 80 GHz and a responsivity of 0.6 A/W at a 1550-nm wavelength.
Abstract: Lithium niobate on insulator (LNOI) has become an intriguing platform for integrated photonics for applications in communications, microwave photonics, and computing. Whereas, integrated devices including modulators, resonators, and lasers with high performance have been recently realized on the LNOI platform, high-speed photodetectors, an essential building block in photonic integrated circuits, have not been demon-strated on LNOI yet. Here, we demonstrate for the first time, heterogeneously integrated modified uni-traveling carrier photodiodes on LNOI with a record-high bandwidth of 80 GHz and a responsivity of 0.6 A/W at a 1550-nm wavelength. The photodiodes are based on an n-down InGaAs/InP epitaxial layer structure that was optimized for high carrier transit time-limited bandwidth. Photodiode integration was achieved using a scalable wafer die bonding approach that is fully compatible with the LNOI platform.
TL;DR: In this article , a transparent optical-subTHz-optical link with record-high single line rates of 240 Gbps and 192 Gbps on a single optical carrier over distances from 5 to 115 m is demonstrated.
Abstract: A transparentOptical-subTHz-Optical link providing record-high single line rates of 240 Gbit/s and 192 Gbit/s on a single optical carrier over distances from 5 to 115 m is demonstrated. Besides a direct mapping of the optical to a 230 GHz subTHz-carrier frequency by means of a uni-traveling carrier (UTC) photodiode, we demonstrate direct conversion of data from the subTHz domain back to the optical domain by a plasmonic modulator. It is shown that the subTHz-to-optical upconversion can even be performed at good quality without any electrical amplifiers. Finally, at the receiver, the local oscillator is employed to directly map the optical signal back to the electrical baseband within a coherent receiver.
TL;DR: In this article , the first micro-transfer printed Si p-i-n photodiodes on a commercially available SiN platform to target wavelengths <850 nm were presented.
Abstract: Silicon nitride (SiN) is used extensively to complement the standard silicon photonics portfolio. However, thus far demonstrated light sources and detectors on SiN have predominantly focused on telecommunication wavelengths. Yet, to unlock the full potential of SiN, integrated photodetectors for wavelengths below 850 nm are essential to serve applications such as biosensing, imaging, and quantum photonics. Here, we report the first, to the best of our knowledge, microtransfer printed Si p-i-n photodiodes on a commercially available SiN platform to target wavelengths <850 nm. A novel heterogeneous integration process flow was developed to offer a high microtransfer printing yield. Moreover, these devices are fabricated with CMOS compatible and wafer-scale technology.
TL;DR: In this article, a top-illuminated avalanche photodiode (APD) was proposed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system.
Abstract: In this work, we demonstrate a novel In0.52Al0.48As based top-illuminated avalanche photodiode (APD), designed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system. In our APD design, the carriers transiting through the dual multiplication (M-)layers are subjected to a stepped-up electric field profile, so they can be energized by the first step and propagate to the second step to trigger the avalanche processes. Such a cascade avalanche process leads to an ultra-high gain bandwidth product (460 GHz) with a 1 A/W responsivity at unit gain. Compared to the high-performance and commercial p-i-n PD and photo-receiver (PD + trans-impedance amplifier (TIA)) installed in the same lidar test bed, our demonstrated APD receiver (without TIA) has a larger S/N ratio under high operation gain (33 A/W) with less optical local-oscillator (LO) power required (0.25 vs. 0.5 mW), while exhibiting a wider dynamic range in each pixel. These advantages in turn lead to the construction of a better quality of 3-D lidar image by using the demonstrated APD.
TL;DR: In this paper , an efficient and generic doping compensation strategy is developed to improve the detectivity of infrared organic photodiodes, which not only reduces the trap density of states and dark currents, but also restrains the nonradiative recombination with improved charge transport and collection.
Abstract: Infrared organic photodiodes have gained increasing attention due to their great application potentials in night vision, optical communication, and all‐weather imaging. However, the commonly occurring high dark current and low detectivity impede infrared photodetectors from portable applications at room temperature. Herein, an efficient and generic doping compensation strategy is developed to improve the detectivity of infrared organic photodiodes. A series of n‐type organic semiconductors is investigated, and it is found that doping compensation strategy not only reduces the trap density of states and dark currents, but also restrains the nonradiative recombination with improved charge transport and collection. As a result, an ultralow noise spectral density of 8 × 10−15 A Hz−1/2 as well as a high specific detectivity over 1013 Jones in 780–1070 nm is achieved at room temperature. More importantly, the high‐performance infrared organic photodiodes can be successfully applied in high‐pixel‐density image arrays without patterning sensing layers. These findings provide important compensation design insights that will be crucial to further improve the performance of infrared organic photodiodes in the future.
TL;DR: In this article , a loop reflector-assisted silicon-germanium waveguide avalanche photodiode with improved responsivity is presented. But the performance of the reflector is limited by the build-up time.
Abstract: We present a loop reflector-assisted silicon-germanium waveguide avalanche photodiode with improved responsivity. Compared to the same APD without the reflector, it has 1.49 times higher responsivity, ~ 1.12 A/W, without compromising the speed performance. It exhibits a 3 dB-bandwidth of ~ 25 GHz, a build-up time limited gain-bandwidth product of ~ 296 GHz, a highest gain-bandwidth product of ~ 497 GHz. Clear eye diagrams are measured at both 32 Gbps NRZ and 64 Gbps PAM4 modulation, and a 1 ~ 2 dB better sensitivity up to -15.7 dBm with 32 Gbps NRZ at a BER of 2.4 ×10 -4 .
TL;DR: In this article, the authors present a modeling tool for the numerical evaluation of antenna coupled uni-travelling carrier photodiodes and experimental evaluation of the fabricated designs.
Abstract: Terahertz generation using high-speed photodiodes has found commercial application in many areas ranging across spectroscopy, imaging and communications. In this paper we discuss the optimization of high-speed photodiodes in terms of bandwidth and output power. We identify some of the main limitations in the generation of high output power in the Terahertz frequency band. We present a modelling tool for the numerical evaluation of antenna coupled uni-travelling carrier photodiodes and experimental evaluation of the fabricated designs. We also present a thermal analysis of the photodiodes alongside pulsed measurements of the output power saturation.
TL;DR: In this article , an interconnected nano-optoelectronic spiking artificial neuron emitter-receiver system with low energy consumption and high spiking dynamical responses is proposed.
Abstract: In this work, we introduce an interconnected nano-optoelectronic spiking artificial neuron emitter-receiver system capable of operating at ultrafast rates (about $100\phantom{\rule{0.2em}{0ex}}\mathrm{ps}/$optical spike) and with low-energy consumption ( pJ/spike). The proposed system combines an excitable resonant tunneling diode (RTD) element exhibiting negative differential conductance, coupled to a nanoscale light source (forming a master node) or a photodetector (forming a receiver node). We study numerically the spiking dynamical responses and information propagation functionality of an interconnected master-receiver RTD node system. Using the key functionality of pulse thresholding and integration, we utilize a single node to classify sequential pulse patterns and perform convolutional functionality for image feature (edge) recognition. We also demonstrate an optically interconnected spiking neural network model for processing of spatiotemporal data at over 10 Gbit/s with high inference accuracy. Finally, we demonstrate an off-chip supervised learning approach utilizing spike-timing-dependent plasticity for the RTD-enabled photonic spiking neural network. These results demonstrate the potential and viability of RTD spiking nodes for low footprint, low-energy, high-speed optoelectronic realization of spike-based neuromorphic hardware.
TL;DR: In this paper , a full-van der Waals (vdWs) 1D p−Te/2D n−Bi2O2Se heterodiode with a rationally designed nanoscale ultra-photosensitive channel is reported.
Abstract: Continuous miniaturization of semiconductor devices is the key to boosting modern electronics development. However, this downscaling strategy has been rarely utilized in photoelectronics and photovoltaics. Here, in this work, a full‐van der Waals (vdWs) 1D p‐Te/2D n‐Bi2O2Se heterodiode with a rationally designed nanoscale ultra‐photosensitive channel is reported. Enabled by the dangling bond‐free mixed‐dimensional vdWs integration, the Te/Bi2O2Se type‐II diodes show a high rectification ratio of 3.6 × 104. Operating with 100 mV reverse bias or in a self‐power mode, the photodiodes demonstrate excellent photodetection performances, including high responsivities of 130 A W−1 (100 mV bias) and 768.8 mA W−1 (self‐power mode), surpassing most of the reports of other heterostructures. More importantly, a superlinear photoelectric conversion phenomenon is uncovered in these nanoscale full‐vdWs photodiodes, in which a model based on the in‐gap trap‐assisted recombination is proposed for this superlinearity. All these results provide valuable insights in light–matter interactions for further performance enhancement of photoelectronic devices.
TL;DR: In this article , a gate-tunable and anti-ambipolar phototransistor is reported based on 1D GaAsSb nanowire/2D MoS2 nanoflake mixed-dimensional van der Waals heterojunctions.
Abstract: The incapability of modulating the photoresponse of assembled heterostructure devices has remained a challenge for the development of optoelectronics with multifunctionality. Here, a gate-tunable and anti-ambipolar phototransistor is reported based on 1D GaAsSb nanowire/2D MoS2 nanoflake mixed-dimensional van der Waals heterojunctions. The resulting heterojunction shows apparently asymmetric control over the anti-ambipolar transfer characteristics, possessing potential to implement electronic functions in logic circuits. Meanwhile, such an anti-ambipolar device allows the synchronous adjustment of band slope and depletion regions by gating in both components, thereby giving rise to the gate-tunability of the photoresponse. Coupled with the synergistic effect of the materials in different dimensionality, the hybrid heterojunction can be readily modulated by the external gate to achieve a high-performance photodetector exhibiting a large on/off current ratio of 4 × 104, fast response of 50 μs, and high detectivity of 1.64 × 1011 Jones. Due to the formation of type-II band alignment and strong interfacial coupling, a prominent photovoltaic response is explored in the heterojunction as well. Finally, a visible image sensor based on this hybrid device is demonstrated with good imaging capability, suggesting the promising application prospect in future optoelectronic systems.
TL;DR: In this paper , a network of dual-gate silicon p-i-n photodiodes, which are compatible with complementary metal-oxide-semiconductor fabrication processes, can perform in-sensor image processing by being electrically programmed into convolutional filters.
Abstract: Complementary metal–oxide–semiconductor (CMOS) image sensors allow machines to interact with the visual world. In these sensors, image capture in front-end silicon photodiode arrays is separated from back-end image processing. To reduce the energy cost associated with transferring data between the sensing and computing units, in-sensor computing approaches are being developed where images are processed within the photodiode arrays. However, such methods require electrostatically doped photodiodes where photocurrents can be electrically modulated or programmed, and this is challenging in current CMOS image sensors that use chemically doped silicon photodiodes. Here we report in-sensor computing using electrostatically doped silicon photodiodes. We fabricate thousands of dual-gate silicon p–i–n photodiodes, which can be integrated into CMOS image sensors, at the wafer scale. With a 3 × 3 network of the electrostatically doped photodiodes, we demonstrate in-sensor image processing using seven different convolutional filters electrically programmed into the photodiode network. A network of dual-gate silicon p–i–n photodiodes, which are compatible with complementary metal–oxide–semiconductor fabrication processes, can perform in-sensor image processing by being electrically programmed into convolutional filters.
TL;DR: In this article, a comprehensive design model is employed to predict and tune the frequency response by incorporating coplanar waveguides (CPWs) with different inductive peaking effects, and two back-illuminated modified uni-traveling-carrier photodiodes (MUTC-PDs) are reported to demonstrate wide bandwidth and high output power performance at D-band (110-170 GHz) regime.
Abstract: Novel back-illuminated modified uni-traveling- carrier photodiodes (MUTC-PDs) are reported to demonstrate wide bandwidth and high output power performance at D-band (110–170 GHz) regime. A comprehensive design model is employed to predict and tune the frequency response by incorporating coplanar waveguides (CPWs) with different inductive peaking effects. As a demonstration, 4.5-μm-diameter photodiodes with two types of CPWs are fabricated to exhibit different frequency response profiles. Both PDs exhibit a 3-dB bandwidth over 150 GHz and the measured frequency responses are in excellent agreement with simulations. Thanks to the proper design of the CPW electrodes, the two PDs exhibit an output power roll-off of only 4.3 dB and 4.8 dB from dc to 170 GHz, respectively, and high saturation performance is maintained over the broadband frequency range of 130–170 GHz.
TL;DR: In this article , an ingenious phototransistor based on WSe2/WS2/WSe2 dual van der Waals (vdW) heterostructures is constructed, performing both high responsivity and detectivity.
Abstract: The excellent semiconducting properties and ultrathin morphological characteristics allow van der Waals (vdW) heterostructures based on 2D materials to be promising channel materials for the next‐generation optoelectronic devices, especially in photodetectors. Although various 2D heterostructure‐based photodetectors have been developed, the unavoidable trade‐off between responsivity and detectivity remains a critical issue for these devices. Here, an ingenious phototransistor based on WSe2/WS2/WSe2 dual‐vdW heterostructures is constructed, performing both high responsivity and detectivity. In the charge neutrality point (gate voltage of −15 V and bias voltage of 1 V), this device demonstrates a pronounced photosensitivity, accompanying with high detectivity of 1.9 × 1014 Jones, high responsivity of 35.4 A W−1, and fast rise/fall time of 3.2/2.5 ms at 405 nm with power density of 60 µW cm−2. Density functional theory calculations, energy band profiles, and optoelectronic characteristics jointly verify that the high performance is ascribed to the distinctive device design, which not only facilitates the separation of photogenerated carriers but also produces a strong photogating effect. As a feasible application, an automotive radar system is demonstrated, proving that the device has considerable potential for application in vehicle intelligent assisted driving.
TL;DR: In this paper , the performance of the short-wave infrared (SWIR) sensitive PbS colloidal quantum dot (CQD) photodetectors is analyzed.
Abstract: Thin-film-based image sensors feature a thin-film photodiode (PD) monolithically integrated on CMOS readout circuitry. They are getting significant attention as an imaging platform for wavelengths beyond the reach of Si PDs, i.e., for photon energies lower than 1.12 eV. Among the promising candidates for converting low-energy photons to electric charge carriers, lead sulfide (PbS) colloidal quantum dot (CQD) photodetectors are particularly well suited. However, despite the dynamic research activities in the development of these thin-film-based image sensors, no in-depth study has been published on their imaging characteristics. In this work, we present an elaborate analysis of the performance of our short-wave infrared (SWIR) sensitive PbS CQD imagers, which achieve external quantum efficiency (EQE) up to 40% at the wavelength of 1450 nm. Image lag is characterized and compared with the temporal photoresponsivity of the PD. We show that blooming is suppressed because of the restricted pixel-to-pixel movement of the photo-generated charge carriers within the bottom transport layer (BTL) of the PD stack. Finally, we perform statistical analysis of the activation energy for CQD by dark current spectroscopy (DCS), which is an implementation of a well-known methodology in Si-based imagers for defect engineering to a new class of imagers.