Efficient Photodetectors Research Articles

Fast and Efficient Sub-Band Gap Photodetection in Al:ZnO/Si Heterojunction by Enhanced Photoexcited Hole Transport via Interfacial Defect States

Fast and Efficient Sub-Band Gap Photodetection in Al:ZnO/Si Heterojunction by Enhanced Photoexcited Hole Transport via Interfacial Defect States

When do we need Pbps photonic chips and what are the challenges?

We estimate the capacity requirement for optical input/output chips boosted by artificial intelligence in computing centers. It is expected that petabits per second (Pbps) capacity on a single chip may be achieved in ten years or so in laboratories. We then study the key challenges in the implementation of such photonic chips, focusing on technical bottlenecks such as laser integration, modulation speed, MUX/DEMUX scaling, photodetector efficiency, and packaging density. We also discuss potential solutions, including novel materials and integration techniques, to enhance performance and reduce power consumption. Our analysis suggests that significant innovations in these areas could lead to the development of compact and efficient Pbps photonic chips by 2035, paving the way for next-generation optical interconnect systems.

Large-scale free-standing Bi2Te3/Si heterostructures developed by a modified solvothermal method for a self-powered and efficient imaging photodetector

Topological insulator bismuth telluride (Bi2Te3), an exotic state of quantum matter, has broad application prospects in next-generation optoelectronic devices. However, photoexcited carriers in Bi2Te3 usually relax rapidly due to the lack of a large band gap. Herein, high-quality Bi2Te3/Si heterojunction is successfully synthesized by a low-cost modified two-step solvothermal method to grow large-scale free-standing Bi2Te3 nanosheets on a Si substrate. Benefiting from the promotion of photogenerated carrier separation and transport by the built-in electric field at the Bi2Te3/Si heterojunction interface, the Bi2Te3/Si heterojunction photodetector exhibits a high responsivity of 16.44 mA W−1, a high specific detectivity of 2.44 × 1011 Jones, and fast rise/recovery times of 11/13 ms under 470 nm illumination at zero bias. Additionally, the device has potential applications in high-resolution imaging. In view of its overall photosensitivity performance and low cost, the Bi2Te3/Si heterojunction synthesized by the solvothermal method has a promising application in fast broadband photodetectors, and also provide a new route for the growth of Bi2Te3 nanosheets on substrates.

Optimizing the optoelectronic properties of broadband FeS2/Si photodetectors via deposition temperature tuning in chemical bath deposition.

This study investigates the fabrication and characterization of n-FeS2/p-Si heterojunction photodetectors using chemical bath deposition (CBD) at deposition temperatures ranging from 50 °C to 80 °C. The impact of temperature on the structural, morphological, and optical properties of FeS2 thin films was evaluated. X-ray diffraction (XRD) revealed polycrystalline cubic FeS2 with improved crystallinity as the deposition temperature increased. The optical energy gaps of the films ranged from 2.41 eV to 1.6 eV, decreasing with higher temperatures. Scanning electron microscopy (FE-SEM) showed that grain size increased from 30 nm to 180 nm as the temperature rose. Hall effect measurements confirmed the n-type conductivity of the film, with mobility decreasing from 5 to 3.17 cm2 V-1 s-1 at higher temperatures. The heterojunctions exhibited rectifying behavior, with the best ideality factor of 1.7 observed at 60 °C. The photodetector fabricated at 60 °C showed superior performance, with a responsivity of 0.37 A W-1 at 520 nm and 0.7 A W-1 at 770 nm, an external quantum efficiency of 52%, and a detectivity of 8 × 1011 Jones at 520 nm, making it the optimal configuration for efficient broadband photodetection.

Regulated Charge Transfer in Donor-Acceptor Metal-Organic Frameworks for Highly-Sensitive Photodetectors.

In photo-induced charge separation, organic thin films with donor and acceptor chromophores are vital for uses such as artificial photosynthesis and photodetection. The main challenges include optimizing charge separation efficiency and identifying the ideal acceptor/donor ratio. Achieving this is difficult due to the variability in molecular configurations within these typically amorphous organic aggregates. Metal-organic frameworks (MOFs) provide a structured solution by enabling systematic design of donor/acceptor blends with adjustable ratios within a crystalline lattice. We demonstrate this approach by incorporating donor and acceptor naphthalenediimide (NDI) chromophores as linkers in a highly oriented, monolithic MOF thin film. By adjusting the NDI acceptor linker concentration during the layer-by-layer assembly of surface-anchored MOF thin films (SURMOFs), we significantly enhanced charge separation efficiency. Surprisingly, the optimum acceptor concentration was only 3%, achieving a forty-fold increase in photodetection efficiency compared to baseline NDI donor-based SURMOFs. This unexpected behaviour was clarified through theoretical analysis enabled by the well-defined crystalline structure of the SURMOFs. Using density functional theory and kinetic Monte Carlo simulations, we identified two opposing effects from acceptors: the positive effect of suppressing undesirable charge carrier recombination is offset at high concentrations by a reduction in charge-carrier mobility.

Next-Generation Self-Powered Photodetectors using 2D Bismuth Oxide Selenide Crystals.

The concept of self-powered photodetectors has attracted significant attention due to their versatile applications in areas such as intelligent systems and hazardous substance detection. Among these, p-n junction and Schottky junction photodetectors are the most widely studied types; however, their fabrication processes are often complex and costly. To overcome these challenges, we focused on the emerging self-powered, ultrasensitive photodetector platform based on photoelectrochemical (PEC) principles. This platform leverages the unique properties of the emerging material bismuth oxide selenide (Bi2O2Se), which features a wide bandgap (∼2 eV) and a high absorption coefficient. We utilized chemical exfoliation to obtain thin layers of Bi2O2Se, enabling highly efficient photodetection. The device characterization demonstrated impressive performance metrics, including a responsivity of 97.1 μA W-1 and a specific detectivity of 2 × 108 cm Hz 1/2 W-1. The PEC photodetector also exhibits broad-spectrum sensitivity, from blue to infrared wavelengths, and features an ultrafast response time of ∼82 ms and a recovery time of ∼86 ms, highlighting its practical potential. Moreover, these self-powered photodetectors show excellent stability in electrochemical environments, positioning them promising candidates for integration into future high-efficiency devices.

Van der Waals ZnO/HfSn2N4 Heterojunction with Exceptional Photoresponse for Photodetectors.

Two-dimensional van der Waals heterojunctions represent a promising avenue for a spectrum of optoelectronic endeavors. Nonetheless, their deployment has been somewhat constrained by the suboptimal efficiency of the photocurrent generated. In this article, a ZnO/HfSn2N4 heterojunction is proposed to achieve high photoresponse efficiency. First-principles calculations are utilized to confirm that this heterojunction possesses thermal stability with a direct bandgap (1.36 eV). It exhibits a high light absorption coefficient and high carrier mobility (2.51 × 103 cm2 V-1 s-1), and biaxial strain has a significant effect on the modulation of the band structure. As the tensile strain increases, the bandgap changes nonlinearly, transitioning from a type-II to a type-I heterojunction. When compressive strain increases, the bandgap decreases. Quantum transport simulations are employed to calculate the density of states and transmission spectrum of the ZnO/HfSn2N4 model, verifying its excellent photoresponse (a photocurrent peak reaching 4.93 a02/photon and an extinction ratio peak of 75.1). It shows that the ZnO/HfSn2N4 heterojunction is a potentially efficient photodetector.

Pt/ZnO and Pt/few-layer graphene/ZnO Schottky devices with Al ohmic contacts using Atlas simulation and machine learning

The search for highly efficient photodetectors, driven by various applications ranging from environmental monitoring to communication systems and imaging, continues to drive research into novel materials and innovative device architectures. This paper offers an in-depth comparative analysis to optimize the performance of two types of Schottky ultraviolet (UV) photodetectors: platinum (Pt)/zinc oxide (ZnO) and Pt/few-layer graphene (FLG)/ZnO, both featuring aluminum (Al) ohmic contacts. The study systematically examines and compares the electrical and optical characteristics of these two photodetector configurations using the Silvaco TCAD simulation tool and machine learning regression models. The research outcomes demonstrate that the proposed photodetector configurations exhibit remarkable improvements, showcasing their substantial potential for superior performance in UV applications. The Pt/ZnO photodetector demonstrates a dark current density of 8.2 × 10−11 pA/cm2, a photocurrent density of 0.26 μA/cm2, a 3-dB cut-off frequency of 85.4 GHz, an external quantum efficiency of 90.41%, and an external photocurrent responsivity of 0.26A/W, at a bias of −1.0 V. On the other hand, Pt/FLG/ZnO photodetector demonstrates near zero dark current density, a photocurrent density of 0.2 μA/cm2, a 3-dB cut-off frequency of 2.44 THz, an external quantum efficiency of 68.52%, and an external photocurrent responsivity of 0.2 A/W at a bias of −1.0 V. Furthermore, a comprehensive comparative analysis of various machine-learning regression models is conducted, validating the simulation findings and providing a predictive framework for optimizing the photodetector's performance. Each machine-learning regression model is evaluated by getting root mean squared error and R2 values across different test set sizes to assess their accuracy in predicting the photodetector's characteristics. This study underscores the promising role of cutting-edge materials and computational techniques in advancing the development of next-generation optoelectronic devices with enhanced capabilities and performance.

Black Phosphorus for Mid-Infrared Optoelectronics: Photophysics, Scalable Processing, and Device Applications.

High efficiency mid-infrared (λ = 3-8 μm) light emitters and photodetectors are pivotal for advancing next-generation optoelectronics. However, narrow-bandgap semiconductors face fundamental challenges such as pronounced nonradiative carrier recombination and thermally generated noise, which impede device performance. Recently, two-dimensional layered black phosphorus (BP) and its alloys have attracted substantial interest for mid-infrared device applications, demonstrating superior performance relative to conventional III-V and II-VI semiconductors with similar bandgaps. In this review, we discuss the optical properties of BP, contrasting these with those of covalent compounds. Owing to its inherently self-terminated surface structure and reduced nonradiative recombination, BP exhibits high performance in light emission and photodetection at room temperature. Furthermore, this review highlights recent advances in the large-area processing of BP thin films, paving the way for practical device applications and integration. Finally, we explore ongoing challenges and emerging opportunities in the utilization of BP for functional mid-infrared devices.

Near-unity quantum efficiency of self-powered broadband photovoltaic black Si photodetectors with passivated Schottky junction

Near-unity quantum efficiency of self-powered broadband photovoltaic black Si photodetectors with passivated Schottky junction

Improved experimental scheme for the generation of pair coherent state in traveling-wave optical fields

Abstract Pair coherent state (PCS) is a two-mode non-Gaussian state recently generated within spatially confined superconducting cavities. Under typical conditions, it is unsuitable for performing global quantum missions in open space. Several methods have been proposed to generate this state with the capability to propagate unrestrictedly. However, these methods employed an excessive amount of unnecessary physical resources or relied on coherent displacement within the low regime. This paper presents a novel experimental approach to generate this state, specifically designed for facilitating long-distance quantum information processing and communication tasks. The method involves the utilization of two weak cross-Kerr nonlinear media, two balanced beam splitters, and an on/off photodetector. Furthermore, the input comprises three CSs with high amplitudes. These physical resources are potentially accessible within existing technology. The analysis of success probability and fidelity demonstrates that the PCS can be successfully generated with a high coherent parameter amplitude, even in scenarios where the photodetector efficiency is low, provided that the coherent amplitudes are sufficiently high.

Photodetector application of CuO nanoparticles on porous silicon fabricated by laser ablation in liquid at diverse laser energies

Abstract This paper describes the synthesis and analysis of a photodetector made of copper oxide nanoparticles (CuONPs) embedded in a porous silicon (PS) matrix. CuONPs were generated utilizing pulsed laser ablation in ethanol (PLAL), while a porous silicon-(PS) substrate was created via photo-assisted electrochemical etching. An investigation is conducted on the optical, structural, and electrical characteristics of CuONPs/PS devices, with a focus on their dependence on laser energy. The X-ray diffraction analysis reveals the presence of distinct peaks associated with a copper cubic structure, demonstrating the successful synthesis of CuONPs that have been deposited onto PS. The study using field emission scanning electron microscopy revealed that the particles exhibited spherical form. The CuO-nanocolloids exhibited a linear relationship between laser power and absorption, and their surface plasmon resonance peaks were clearly visible at 570–590 nm. Band gaps of 1.70, 1.61, 1.81, and 1.90 eV were found for CuONPs produced at 500, 600, 700, and 800 mJ of laser energy, respectively, according to the optical characteristics. The greatest responsivity of the CuO-NPs/PS photodetector, manufactured at an energy level of 700 mJ, was 0.135345 A/W at 450 nm, as determined by the optoelectronic characteristics. As a result of combining PS with CuONPs, the devices shown in this work have the ability to function as highly efficient photodetectors.

Modulating Eco-friendly Colloidal AgGaS2 Quantum Dots for Highly Efficient Photodetection and Image Sensing via Direct Growth of Ternary AgInS2 Shell.

Tailoring the optoelectronic characteristics of colloidal quantum dots (QDs) by constructing a core/shell structure offers the potential to achieve high-performing solution-processed photoelectric conversion and information processing applications. In this work, the direct growth of wurtzite ternary AgInS2 (AIS) shell on eco-friendly AgGaS2 (AGS) core QDs is realized, giving rise to broadened visible light absorption, prolonged exciton lifetime and enhanced photoluminescence quantum yield (PLQY). Ultrafast transient absorption spectroscopy demonstrats that the photoinduced carrier separation and transfer kinetics of AGS QDs are significantly optimized following the AIS shell coating. As-synthesized environmentally benign AGS/AIS core/shell QDs are employed to fabricate photodetectors (PDs), showing a remarkable responsivity of 38.4 AW-1 and a detectivity of 2.4×1012 Jones under visible light illumination (405 nm). Moreover, the fabricated QDs-PDs exhibit superior image-sensing capability to record complex patterns with high resolution (160×160 pixels) under visible light illumination at 405 and 532 nm. The findings indicate that the direct growth of multinary narrow-band shell materials on eco-friendly QDs holds great promise to implement future "green", cost-effective and high-performance optoelectronic sensing/imaging systems.

Enhancement in photo-response of CuZnS nanocrystals-based photodetector using asymmetric work function electrodes

In this study, an efficient visible light photodetector has been fabricated by using heavy metal-free CuZnS Nanocrystals with average particle size of 13 ± 1 nm and has been synthesized by a microwave (MW) assisted synthesis technique. The optical band gap of this nanocrytstal is ∼1.7 eV and has an absorbance spectra ranging from 300 to700 nm. This low bandgap nanocrystals has been used to fabricate a photoconductor device with a CuZnS/ZnO bilayer structure. Besides, the device performance has been enhanced by using an asymmetric work-function lateral electrodes. The work-function difference between the electrodes gives a driven voltage between the electrodes, which allows faster collection of charge carriers from the device. As a consequence, a significant photocurrent is generated by the device even without any external bias. The self-biased (at 0 V) external quantum efficiency (EQE) of this device is ∼ 4 % (at 430 nm) whereas this value reaches ∼ 20 % under 2 V external bias. The device possesses the responsivity (Rλ) and detectivity (D) of 8.8 A/W and 3.8 × 1012 Jones at 320 nm respectively under 2 V external bias.

Лазерная оптико-телевизионная активно-импульсная система подводного видения

The article is devoted to the practical application of the active-pulse observation method to provide underwater vision in conditions of diffusing seawater. The laser optical-television active-pulse underwater vision system (APS UV) developed for the implementation of this method, based on synchronized pulsed laser illumination of objects of observation and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure «Third+ Generation Image Intensifier Tube with extended blue-green spectral region – Digital CMOS-matrix», provides the formation of video images of underwater objects in seawater with the determination of the range to them. A laser optical-television active-pulse underwater vision system (AIS PV) developed for the implementation of this method, based on synchronized pulsed laser illumination of underwater observation objects and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure “III+ generation electron-optical converter by – digital CMOS matrix”, which provides the formation of video images of underwater objects in seawater with the determination of the range to them. The article provides information on the physical prerequisites for the technical implementation of underwater vision in scattering seawater, as well as information on technical solutions for creating key elements of APS UV that can increase the range of vision by cutting off back scattering interference when observing in seawater. This advantage distinguishes APS UV from conventional optical television systems, in which back scattering is superimposed on the resulting image of the object, significantly reducing the range of vision and the quality of the resulting image. The results of the work performed are aimed at increasing the contrast of the image of the observed underwater object and, consequently, the range of vision of the APS UV. The article describes the developed model of the APS UV.

The enhanced characteristics of bipolar phototransistor with huge amplification

Heterojunction devices based on low-dimensional materials have the potential for convenient and efficient photodetection applications. In this study, we demonstrate a van der Waals (vdW) heterojunction device constructed by p-ZrGeTe4 and n-MoS2. Forming a p-n junction, the response speed of the device increased by 6 orders of magnitude compared to devices with individual MoS2. To further improve the responsivity of the device, a bipolar phototransistor (PTD) was prepared based on the p-n junction. The PTD achieves the photocurrent gain of almost 40. This PTD achieves high responsivity of 1.48 A W−1, and the corresponding specific detectivity can reach 3 × 1014 Jones in low frequencies. Under low frequencies, the noise of the device is dominated by generation–recombination noise; and as the frequency increases, it gradually becomes dominated by 1/f noise. The PTD is competitive in optoelectronics and promising in high-performance integrated devices.

Experimental Demonstration of Improvement in Near-Infrared Photodetection Efficiency by Plasmonic Diffraction

Experimental Demonstration of Improvement in Near-Infrared Photodetection Efficiency by Plasmonic Diffraction

Centimeter-scale single-crystal hexagonal boron nitride freestanding thick films as high-performance VUV photodetectors

Large-scale hexagonal boron nitride (h-BN) single crystals are highly desirable not only as the substrate or dielectric for van der Waals heterostructures, but also the promising candidates in optoelectronics, electronics, detectors, as well as recently boomed room-temperature single-photon sources. Here, we report the synthesis of centimeter-scale single-crystal h-BN films with hundreds of micrometer thickness via the metal flux method. The growth control along the out-of-plane and in-plane directions of h-BN crystals is realized by the adjustment of NiCr alloy composition, from which the limited solubility of N atoms can be promoted by high diffusion in molten reactants. This also benefits to forming a distinct interface between the synthesized h-BN crystals and the metal ingot, giving rise to an easy exfoliation of the large area high-quality thick films. Such h-BN crystals have been demonstrated as both self-powered flexible and rigid vacuum-ultraviolet photodetectors, allowing for efficient photodetection in terms of high responsivity, rapid response speed, and high operational temperature. A maximum photoresponsivity of 3.35 mA/W is achieved at a wavelength of 185 nm with an operational temperature spanning to 500 °C (and possibly beyond). The large-area freestanding h-BN single crystal described herein reveals great potential as a high-performance photodetector, and versatile platform for other superb electronic and optoelectronic devices.

Flexible transparent conductors with a percolated Ag nanostructure and its application as efficient self-bias plasmonic photodetector

A percolated silver (Ag) nanostructured-based transparent conductor has been deposited by physical vapor deposition (PVD) technique where lateral growth of Ag has been enhanced by a pre-deposited Ag-TiO2 thin film. This Ag-TiO2 film has embedded Ag nanoparticles (NPs) within TiO2 thin film which is grown in a low temperature (100 °C) solution processed technique. This process includes Li4Ti5O12 (LTO) thin film deposition by a sol–gel method followed by ion-exchange (Li+ → Ag+) process to yield an Ag-TiO2 thin film. The percolated Ag network has appeared as soon film mass-thickness reaches close to 10 nm, resulting in an abrupt drop of electrical resistivity of the film. This percolated Ag nanostructured thin film (10 nm Ag/Ag-TiO2/plastic) has resistivity of ∼50 Ω/□ and an average visual transmittance of >70 % up to 450 nm. In higher wavelength range, transparency gradually reduces, and it reaches to ∼50 % at 600 nm which is mostly due to the plasmon absorption of this film. By utilizing its combined optical transparency and surface plasmon absorption, this film has been used to develop plasmonic hot electron photodetectors where Ag-thin film works as transparent electrode as well as plasmon induced photo-excited hot electron generation. Device has been fabricated on a heavily doped n type Si (n++-Si) with a metal–semiconductor-metal (M−S−M) device geometry. External quantum efficiency (EQE) data reveal that photocurrent of this device is mostly generated in the plasmonic absorption region with a peak detectivity of 2.84 × 1012 Jones at 510 nm under −3V external bias. Besides, the device shows fast response with a response time of ∼25 ms.

Computational investigation for electronic, structural, linear/nonlinear optical responses for newly designed organometallic quantum dots

AbstractThe interaction of metallic ($$M^{ + 3}$$ M + 3 )-cations ($$M = {\text{Al}},{\text{Cu}},{\text{Zn}},{\text{In}},{\text{Ga}},{\text{Ge}},{\text{Sb}},{\text{Sn}}$$ M = Al , Cu , Zn , In , Ga , Ge , Sb , Sn ) with an active organic linker result in the formation of organometallic quantum dots (OMQDs). The B3LYP and WB97X interfaces via 6-311G++(d,p) route are used to test the stability, electrical, optical, and nonlinear-optics (NLO) properties. OMQD UV–Vis absorption spectra are computed. Some OMQD have singlet spin states, while others have doublet spin states. Cation mobility and the organic linker nature have a significant impact on both optical and NLO properties. For electron rush via the conduction domain, doublet spins provide more advanced turnabilities than singlets. For singlet-spin Cu-3HPHP QDs, an anomalous NLO response is endorsed. Both Zn-3HPHP and Sn-3HPHP QDs are recognized as the finest contenders. Zn-3HPHP and Sn-3HPHP appear to be the next covenant for highly efficient optoelectronics and avalanche photodetectors.