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A high‐performance broadband photodetector (PD) has been fabricated by using a heavily doped n‐type silicon substrate (n+‐Si) in a lateral photodiode geometry. This self‐biased photodiode fabrication required only two asymmetric work‐function electrodes deposited on top of a clean n+‐Si substrate. Specifically, LiF/Al and MoOx /Ag are used as electrodes where LiF and MoO3 work as n+‐Si/electrode interface layers for Al and Ag electrodes respectively. These two electrodes have a work function difference of ≈1.1 eV which is measured by ultraviolet photoelectron spectroscopy study. Under dark, this lateral contact device shows a rectifying behavior with reverse‐to‐forward current ratio of ≈5.3 × 103 under ±1 V external bias. Moreover, this device shows a very high photoresponse with a dark‐to‐light current ratio (IL/ID) of 2.15 × 104 under white light illumination (600 W m−2) at −1 V operating voltage. Besides, the device shows external quantum efficiency (EQE) of ≈16.1% under self‐biasing (Vext = 0 V) conditions which reaches to 30.2% at −1 V external bias, whereas the device has responsivity (Rλ) and detectivity (D) of 10.2 A W−1 and 9.1 × 1012 Jones, respectively under self‐biasing condition. The peak responsivity (Rλ) and detectivity (D) of these devices reaches to 17.5 A W−1 and 1.6 × 1013 Jones under −1 V external bias. [ABSTRACT FROM AUTHOR]

Breakthroughs brought about by two‐dimensional (2D) materials in the field of photodetection have opened up new possibilities in infrared imaging. However, challenges still exist in fabricating high‐density detector arrays using such materials, which are essential for traditional imaging systems. In this study, we present a state‐of‐the‐art computing imaging system that utilizes a MoTe2/Si self‐powered photodetector coupled with flexible Hadamard modulation algorithms. This system demonstrates remarkable capability to produce high‐quality images in the shortwave infrared (SWIR) band, surpassing the capabilities of devices based on alternative material systems. The exceptional infrared imaging capability primarily stems from the MoTe2/Si photodetector's inherent features, including an ultra‐wide spectral range (265–1550 nm) and extremely high sensitivity (linear dynamic range (LDR) up to 123 dB, responsivity (R) up to 0.33 A W–1, external quantum efficiency (EQE) up to 43% and a specific detectivity (D*) exceeding 2.9 × 1011 Jones). Moreover, the imaging system demonstrates the ability to achieve high‐quality edge imaging of objects in the SWIR band (1550 nm), even in strong scattering environments and under low sampling rate conditions (sampling rate of 25%). We believe that this work will effectively advance the application scope of 2D materials in the field of computational imaging in SWIR bands. [ABSTRACT FROM AUTHOR]

Heterojunctions formed between undoped and Eu‐doped NiO nanofibers (NFs) and n‐Si were fabricated by electrospinning the NiO:Eu NFs onto Si. Since the photoresponse of the Eu‐doped NiO‐containing device was better than the undoped one, the study focused on the doped NiO‐containing device. This was explained by the increase in electron kinetics in terms of the active role of Eu in bonding with the 4f orbitals and the s, d, and f states of NiO. Electro‐optical measurements of the NiO:Eu NFs/n‐Si heterojunction were performed in the visible region depending on the light intensity and in the UV and NIR regions for 10 mW/cm2 powers. It was observed that the device exhibits a good level of rectification properties and responds very well to all lights. At all three light sources, the heterojunction photodetector exhibited self‐powered behavior. Furthermore, for 10 mW/cm2 light intensity, the NiO:Eu NFs/n‐Si photodetector achieved R values of 1.84 A/W at 365 nm, 0.98 A/W at 395 nm, and 1.54 A/W at 850 nm, while it is 0.12 A/W for visible light. Besides, the device showed an external quantum efficiency of 625% and this was attributed to the photocurrent gain. In self‐driven mode, D* values have been determined as 3.0 × 1012 Jones, 2.6 × 1012 Jones, and 2.9 × 1012 Jones for 365, 395, and 850 nm, respectively. The performance of NiO under UV light was attributed to the absorption of NiO under UV light, as well as the very good excitation of (Eu3+) ions by UV light. [ABSTRACT FROM AUTHOR]

Photodetectors converting light into electrical signals are crucial in various applications. The pursuit of high-performance photodetectors with high sensitivity and broad spectral range simultaneously has always been challenging in conventional semiconductor materials. Graphene, with its zero bandgap and high electron mobility, is an attractive candidate, but its low light absorption coefficient restricts its practical application in light detection. Integrating graphene with light-absorbing materials like PbS quantum dots (QDs) can potentially enhance its photodetection capabilities. Here, this work presents a broadband photodetector with enhanced sensitivity based on a graphene–PbS QD heterostructure. The device leverages the high carrier mobility of graphene and the strong light absorption of PbS QDs, achieving a wide detection range from ultraviolet to near-infrared. Employing a simple spinning method, the heterostructure demonstrates ultrahigh responsivity up to the order of 107 A/W and a specific detectivity on the order of 1013 Jones, showcasing significant potential for photoelectric applications. [ABSTRACT FROM AUTHOR]

Abstract Breakthroughs brought about by two‐dimensional (2D) materials in the field of photodetection have opened up new possibilities in infrared imaging. However, challenges still exist in fabricating high‐density detector arrays using such materials, which are essential for traditional imaging systems. In this study, we present a state‐of‐the‐art computing imaging system that utilizes a MoTe2/Si self‐powered photodetector coupled with flexible Hadamard modulation algorithms. This system demonstrates remarkable capability to produce high‐quality images in the shortwave infrared (SWIR) band, surpassing the capabilities of devices based on alternative material systems. The exceptional infrared imaging capability primarily stems from the MoTe2/Si photodetector's inherent features, including an ultra‐wide spectral range (265–1550 nm) and extremely high sensitivity (linear dynamic range (LDR) up to 123 dB, responsivity (R) up to 0.33 A W–1, external quantum efficiency (EQE) up to 43% and a specific detectivity (D*) exceeding 2.9 × 1011 Jones). Moreover, the imaging system demonstrates the ability to achieve high‐quality edge imaging of objects in the SWIR band (1550 nm), even in strong scattering environments and under low sampling rate conditions (sampling rate of 25%). We believe that this work will effectively advance the application scope of 2D materials in the field of computational imaging in SWIR bands.

An efficient room-temperature self-powered, broadband (300 ​nm–1100 nm) photodetector based on a CuO–TiO2/TiO2/p-Si(100) heterostructure is demonstrated. The CuO–TiO2 nanocomposites were grown in a two-zone horizontal tube furnace on a 40 ​nm TiO2 thin film deposited on a p-type Si(100) substrate. The CuO–TiO2/TiO2/p-Si(100) devices exhibited excellent rectification characteristics under dark and individual photo-illumination conditions. The devices showed remarkable photo-response under broadband (300–1100 ​nm) light illumination at zero bias voltage, indicating the achievement of highly sensitive self-powered photodetectors at visible and near-infrared light illuminations. The maximum response of the devices is observed at 300 ​nm for an illumination power of 10 ​W. The response and recovery times were calculated as 86 ​ms and 78 ​ms, respectively. Moreover, under a small bias, the devices showed a prompt binary response by altering the current from positive to negative under illumination conditions. The main reason behind this binary response is the low turn-on voltage and photovoltaic characteristics of the devices. Under illumination conditions, the generation of photocurrent is due to the separation of photogenerated electron-hole pairs within the built-in electric field at the CuO–TiO2/TiO2 interface. These characteristics make the CuO–TiO2/TiO2 broadband photodetectors suitable for applications that require high response speeds and self-sufficient functionality.

Self‐powered photodetectors with dual‐polarity response have great advantages in processing complex light information that is proven to be applied in switchable light imaging, optical communication, and spectral band distinction. Here, a novel strategy for designing self‐powered photodetectors by introducing the double symmetric Schottky junctions at the semiconductor‐metal interfaces is proposed, which guarantees the linear response characteristic and dominates the transfer of photogenerated carriers without external bias. Narrow bandgap semiconductor SnTe is employed as the photosensitive material. The bandgap is characterized to be 126 meV, showing great potential for wide spectrum response. As the consequence of selective excitation of unilateral Schottky junction and switching of electric field polarity, the device obtains a dual‐polarity photoresponse, which can be tuned from −14.8 to 13.5 µV. Moreover, an ultra‐broadband photoresponse from near‐infrared 808 nm to far infrared 10.6 µm is achieved with deep exploration of the working mechanism. The synergistic effect of photo thermoelectricity and photoconductivity created a high photoresponsivity of 0.35 mV W−1 excited by 10.6 µm at room temperature. This work provides a novel design strategy for self‐powered photodetectors with a dual‐polarity powered principle, which can take full advantage of the directivity of the photoresponse to identify optical information. [ABSTRACT FROM AUTHOR]

The development of photodetectors is crucial in fields such as optical communication, image sensing, medical devices and military equipment, where high sensitivity is paramount. We fabricated an ambipolar photodiode using monolayer triclinic ReSe2, synthesized by chemical vapor deposition on p-type Si substrate. The photodetector has a broadband response range from 405 to 1100 nm. The device exhibits high sensitivity to NIR radiation with a high Iph/Idark (ON/OFF) ratio of 5.8 x 104, responsivity (R) of 465 A/W, and specific detectivity (D) of 4.8 x 1013 Jones at open circuit voltage (Voc), indicating photovoltaic behavior. Our ReSe2/Si heterojunction photodetector also exhibits low dark current of 1.4 x 10-9 A and high external quantum efficiency (EQE) of 54368.2% for 1060 nm at -3 V, demonstrating a photoconductive gain. The maximum responsivity (R = 465 A/W) can be achieved at -3 V reverse bias under 1060 nm. The device has a high ideality factor (4.8) and power coefficient (α = 0.5), indicating the presence of interface and sub-gap states that enhance device responsivity at lower illumination intensities by re-exciting trapped carriers into the conduction band. Our results offer important insights into the underlying photo-physics of the ReSe2/Si heterojunction and propose promising avenues for developing advanced broadband photodetectors of high performance. [ABSTRACT FROM AUTHOR]

Photodetectors converting light into electrical signals are crucial in various applications. The pursuit of high-performance photodetectors with high sensitivity and broad spectral range simultaneously has always been challenging in conventional semiconductor materials. Graphene, with its zero bandgap and high electron mobility, is an attractive candidate, but its low light absorption coefficient restricts its practical application in light detection. Integrating graphene with light-absorbing materials like PbS quantum dots (QDs) can potentially enhance its photodetection capabilities. Here, this work presents a broadband photodetector with enhanced sensitivity based on a graphene–PbS QD heterostructure. The device leverages the high carrier mobility of graphene and the strong light absorption of PbS QDs, achieving a wide detection range from ultraviolet to near-infrared. Employing a simple spinning method, the heterostructure demonstrates ultrahigh responsivity up to the order of 107 A/W and a specific detectivity on the order of 1013 Jones, showcasing significant potential for photoelectric applications.

As a wide band-gap p-type semiconductor, α-MnSe has been expected to make up for the scarcity of two-dimensional (2D) semiconductor materials, which is crucial for the construction of multifunctional and miniaturized p-n junctions. Herein, we report the synthesis of single crystalline α-MnSe with its domain size, thickness and coverage controlled by hydrogen modulated CVD. The back-gate FET device was fabricated to study the electrical properties of α-MnSe. Moreover, the α-MnSe-based photodetector exhibits a broadband photo-response ranging from 532 nm to 980 nm with response times as low as ∼ 20 ms, comparable to most 2D materials.

In this study, we employ the sol–gel method to fabricate MoS2 films with a controllable thickness. The resulting colloidal configuration can be directly spin-coated onto various substrates (e.g., Si, SiO2, GaN, and sapphire), leading to the formation of smooth MoS2 films after annealing. Based on this technique, we construct a two-dimensional MoS2/p-GaN van der Waals (vdWs) heterostructure photodetector comprising n-MoS2 and p-GaN. The high crystal quality of MoS2 and the internal electric field of the MoS2/p-GaN heterostructure p–n junction enable efficient separation of photogenerated carriers, resulting in enhanced exciton collection by the electrode at 416 nm. This configuration achieves a high photo response of 35.6 A/W and a rapid response time of 200 ms, surpassing that of a single MoS2 thin film. Furthermore, when combined with p-GaN, the photodetector's response spectrum extends to the ultraviolet region, exhibiting an impressive 8.4 A/W light response and a quick response time of 280 ms. This demonstrates a favorable synergistic effect. These exceptional properties establish n-MoS2/p-GaN heterostructure photodetectors as highly competitive next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

As one of the most promising materials for two-dimensional transition metal chalcogenides (2D TMDs), molybdenum diselenide (MoSe2) has great potential in photodetectors due to its excellent properties like tunable bandgap, high carrier mobility, and excellent air stability. Although 2D MoSe2-based photodetectors have been reported to exhibit admired performance, the large-area 2D MoSe2 layers are difficult to be achieved via conventional synthesis methods, which severely impedes its future applications. Here, we present the controllable growth of large-area 2D MoSe2 layers over 3.5-inch with excellent homogeneity by a simple post-selenization route. Further, a high-quality n-MoSe2/p-Si van der Waals (vdW) heterojunction device is in-situ fabricated by directly growing 2D n-MoSe2 layers on the patterned p-Si substrate, which shows a self-driven broadband photoresponse ranging from ultraviolet to mid-wave infrared with an impressive responsivity of 720.5 mA·W−1, a high specific detectivity of 1013 Jones, and a fast response time to follow nanosecond pulsed optical signal. In addition, thanks to the inch-level 2D MoSe2 layers, a 4 × 4 integrated heterojunction device array is achieved, which has demonstrated good uniformity and satisfying imaging capability. The large-area 2D MoSe2 layer and its heterojunction device array have great promise for high-performance photodetection and imaging applications in integrated optoelectronic systems. [ABSTRACT FROM AUTHOR]

Broadband photodetectors (PDs) with low detection limits hold significant importance to next‐generation optoelectronic devices. However, simultaneously detecting broadband (i.e., X‐ray to visible regimes) and weak lights in a single semiconducting material remains highly challenging. Here, by alloying iodine‐substituted short‐chain cations into the 3D FAPbI3 (FA = formamidine), a new 2D bilayered lead iodide hybrid perovskite, (2IPA)2FAPb2I7 (1, 2IPA = 2‐iodopropylammonium), that enables addressing this challenge is reported. Such a 2D multilayered structure and lead iodide composition jointly endow 1 with a minimized dark current (6.04 pA), excellent electrical property, and narrow bandgap (2.03 eV), which further gives it great potential for detecting broadband weak lights. Consequently, its high‐quality single crystal PDs exhibit remarkable photoresponses to weak ultraviolet–visible lights (377–637 nm) at several tens of nW cm−2 with high responsivities (>102 mA W−1) and significant detectivities (>1012 Jones). Moreover, 1 has an excellent X‐ray detection performance with a high sensitivity of 438 µC Gy−1 cm−2 and an ultralow detection limit of 20 nGy s−1. These exceptional attributes make 1 a promising material for broadband weak lights detection, which also sheds light on future explorations of high‐performance PDs based on 2D hybrid perovskites. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials have been considered promising candidates for next-generation optoelectronics. However, the performance of 2D photodetectors still has much room for improvement due to weak light absorption of planar 2D materials and lack of high-quality heterojunction preparation technology. Notably, 2D materials integrating with mature bulk semiconductors are a promising pathway to overcome this limitation and promote the practical application on optoelectronics. In this work, we present the patterned assembly of MoSe2/pyramid Si mixed-dimensional van der Waals (vdW) heterojunction arrays for broadband photodetection and imaging. Benefited from the light trapping effect induced enhanced optical absorption and high-quality vdW heterojunction, the photodetector demonstrates a wide spectral response range from 265 to 1550 nm, large responsivity up to 0.67 A·W−1, high specific detectivity of 1.84 × 1013 Jones, and ultrafast response time of 0.34/5.6 μs at 0 V. Moreover, the photodetector array exhibits outstanding broadband image sensing capability. This study offers a novel development route for high-performance and broadband photodetector array by MoSe2/pyramid Si mixed-dimensional heterojunction. [ABSTRACT FROM AUTHOR]

Flexible photodetectors with ultra‐broadband sensitivities, fast response, and high responsivity are crucial for wearable applications. Recently, van der Waals (vdW) Weyl semimetals have gained much attention due to their unique electronic band structure, making them an ideal material platform for developing broadband photodetectors from ultraviolet (UV) to the terahertz (THz) regime. However, large‐area synthesis of vdW semimetals on a flexible substrate is still a challenge, limiting their application in flexible devices. In this study, centimeter‐scale type‐II vdW Weyl semimetal, Td‐MoTe2 films, are grown on a flexible mica substrate by molecular beam epitaxy. A self‐powered and flexible photodetector without an antenna demonstrated an outstanding ability to detect electromagnetic radiation from UV to sub‐millimeter (SMM) wave at room temperature, with a fast response time of ≈20 µs, a responsivity of 0.53 mA W−1 (at 2.52 THz), and a noise‐equivalent power (NEP) of 2.65 nW Hz−0.5 (at 2.52 THz). The flexible photodetectors are also used to image shielded items with high resolution at 2.52 THz. These results can pave the way for developing flexible and wearable optoelectronic devices using direct‐grown large‐area vdW semimetals. [ABSTRACT FROM AUTHOR]

2D III-VI semiconductors have emerged as promising materials for optoelectronic devices due to their tunable bandgaps, efficient light absorption and high carrier mobility. Among III-VI group, 2D indium telluride (InTe) has been studied very little compared with its well-known congeners such as InSe and GaSe. Although InTe possesses remarkable electrical and optical properties, the investigation of its device applications is greatly hindered due to the shortage of scalable synthesis method. Here, we synthesized centimeter-scale 2D InTe films via a pulsed laser deposition method. The structure of as-grown InTe films was systematically studied, exhibiting good continuity, uniformity and high degree of crystallinity. Meanwhile, layer-dependent bandgaps (1.21∼1.65 eV) were observed from the optical characterization. The InTe based photodetectors show a broadband photoresponse from ultraviolet (370 nm) to near-infrared region (980 nm). The photoresponsivity and detectivity of the InTe photodetectors can achieve 6.35 A/W and 1.55×1011 under 370 nm illumination, respectively, which outperform many photodetectors based on large-area 2D materials. Notably, InTe photodetectors also demonstrate strong layer-dependent photoresponse from 2 L to 10 L upon different wavelength illumination. Our work will inspire the research interests to further develop the practical applications of 2D InTe in the field of photodetection devices.

Abstract Platinum diselenide (PtSe2) has shown great potential as a candidate two‐dimensional (2D) material for broadband photodetectors and electrocatalysts because of its unique properties compared to conventional 2D transition metal dichalcogenides. Synthesis of 2D PtSe2 with controlled layer number is critical for engineering the electronic behavior to be semiconducting or semimetallic for targeted applications. Electrochemical exfoliation has been investigated as a promising approach for mass‐producing in a cost‐effective manner, but obtaining high‐quality films with control over electronic properties remains difficult. Here, we demonstrate wafer‐scale 2D PtSe2 films with pre‐determined electronic types based on a facile solution‐based strategy. Semiconducting or semimetallic PtSe2 nanosheets with large lateral sizes are produced via electrochemically driven molecular intercalation, followed by centrifugation‐based thickness sorting. Finally, gate‐tunable broadband visible and near‐infrared photodetector arrays are realized based on semiconducting PtSe2 nanosheet films, while semimetallic films are used to create catalytic electrodes for overall water splitting with long‐term stability.

Abstract Broadband photodetectors (PDs) with low detection limits hold significant importance to next‐generation optoelectronic devices. However, simultaneously detecting broadband (i.e., X‐ray to visible regimes) and weak lights in a single semiconducting material remains highly challenging. Here, by alloying iodine‐substituted short‐chain cations into the 3D FAPbI3 (FA = formamidine), a new 2D bilayered lead iodide hybrid perovskite, (2IPA)2FAPb2I7 (1, 2IPA = 2‐iodopropylammonium), that enables addressing this challenge is reported. Such a 2D multilayered structure and lead iodide composition jointly endow 1 with a minimized dark current (6.04 pA), excellent electrical property, and narrow bandgap (2.03 eV), which further gives it great potential for detecting broadband weak lights. Consequently, its high‐quality single crystal PDs exhibit remarkable photoresponses to weak ultraviolet–visible lights (377–637 nm) at several tens of nW cm−2 with high responsivities (>102 mA W−1) and significant detectivities (>1012 Jones). Moreover, 1 has an excellent X‐ray detection performance with a high sensitivity of 438 µC Gy−1 cm−2 and an ultralow detection limit of 20 nGy s−1. These exceptional attributes make 1 a promising material for broadband weak lights detection, which also sheds light on future explorations of high‐performance PDs based on 2D hybrid perovskites.

Abstract Flexible photodetectors with ultra‐broadband sensitivities, fast response, and high responsivity are crucial for wearable applications. Recently, van der Waals (vdW) Weyl semimetals have gained much attention due to their unique electronic band structure, making them an ideal material platform for developing broadband photodetectors from ultraviolet (UV) to the terahertz (THz) regime. However, large‐area synthesis of vdW semimetals on a flexible substrate is still a challenge, limiting their application in flexible devices. In this study, centimeter‐scale type‐II vdW Weyl semimetal, Td‐MoTe2 films, are grown on a flexible mica substrate by molecular beam epitaxy. A self‐powered and flexible photodetector without an antenna demonstrated an outstanding ability to detect electromagnetic radiation from UV to sub‐millimeter (SMM) wave at room temperature, with a fast response time of ≈20 µs, a responsivity of 0.53 mA W−1 (at 2.52 THz), and a noise‐equivalent power (NEP) of 2.65 nW Hz−0.5 (at 2.52 THz). The flexible photodetectors are also used to image shielded items with high resolution at 2.52 THz. These results can pave the way for developing flexible and wearable optoelectronic devices using direct‐grown large‐area vdW semimetals.

Advancements in technology have made it easier to construct flexible broadband photodetectors for wearable devices, improving light harvesting and detecting capabilities. This work described a new study that used bimetallic sulfide nanosheets (FeSnS) to produce flexible and broadband photodetectors on paper substrates using hand-print method. A simple, economical, one-step hydrothermal technique was employed to synthesise FeSnS materials, which were characterised using XRD, UV–Vis Spectroscopy, FESEM, EDS, XPS, and UPS. Photodetection tests found that 2-FeSnS (Fe at 2 wt%) outperformed similar work on paper-based devices, with a responsivity of 32.4 mA/W under a 470 nm incident wavelength, high specific detectivity, and a response time of 1.16 s. Durability and flexibility testing validated the robustness of the device. The use of a simple hydrothermal synthesis and hand-print fabrication method to create high-performance, eco-friendly, and flexible photodetectors is novel, expanding their potential applications in wearable electronics, environmental monitoring, and low-cost disposable sensing platforms. • Using bimetallic sulfide (FeSnS) nanosheets in photodetectors taps into their unique properties, enhancing performance. • FeSnS materials are synthesized using a single-step hydrothermal technique. • Hand-printed devices on flexible, eco-friendly paper substrates combine sustainability with cost-effective production. • High specific detectivity, fast response times (1.16), and high responsivity (32.4 mA/W) were attained at 470 nm wavelength. [ABSTRACT FROM AUTHOR]

The growing interest in carbon dots (CDs) arises from their diverse applications and unique properties. This study addresses challenges in CDs for photodetector (PD) applications, specifically surface defects and trap states hindering efficient charge transport. CDs/P3HT composites were prepared to overcome these issues by incorporating CDs in a poly(3-hexylthiophene) (P3HT) matrix. Broad absorption in spectroscopic characterization revealed its utility in fabricating a broadband PD. The CDs/P3HT PD displays a remarkable broadband photoresponse, spanning both UV and visible regions. The CDs and P3HT are effectively combined via non-covalent π-π interactions constituted by their conjugated systems. The π-π interaction increases electron delocalization and facilitates efficient charge transfer due to band alignment at the junction interface. Hence, fabricated CDs/P3HT PD demonstrated enhanced photocurrent compared to pure CDs, exhibiting high responsivity of 6.12 × 10−3 AW−1 and detectivity of 0.69 × 109 Jones. This study highlights the potential of CD/P3HT composites for broadband photodetector applications with enhanced photoelectric conversion. [Display omitted] • Synthesized CDs using microwave method and prepared CDs/P3HT composite. • CDs/P3HT exhibited a broadband photoresponse in both UV and visible regions. • Effective distribution of CDs/P3HT heterojunctions eases exciton dissociation. • Energy band alignment between CDs and P3HT provides efficient charge transfer. • The CDs/P3HT photodetector gave substantial Responsivity, detectivity and (I P /I D). [ABSTRACT FROM AUTHOR]

The low responsivity of conventional Silicon photodiodes in ultraviolet and near-infrared regimes restricts their utility as broadband photodetectors (BBPDs). Despite ongoing investigations into various p-n heterostructures for Silicon-based BBPDs, challenges such as high dark current (I _dark ), low collection efficiency, low detectivity, and compatibility issues with large-scale Silicon-based devices persist. In this context, we have fabricated relatively unexplored n-Er _2 O _3 /p-Si heterojunction-based BBPDs. Polycrystalline Er _2 O _3 thin films (∼110 nm) were deposited on p-Si 〈100〉 substrates by radio frequency magnetron sputtering. Although this process induces a microstrain of approximately 0.022 and a dislocation density of about 0.00303/nm ^2 , the presence of optically active defects is minimal, indicated by a low Urbach energy (∼0.35 eV). X-ray photoelectron spectroscopy (XPS) analysis confirms staggered band alignment at the heterointerface, facilitating efficient charge carrier separation and transport. Consequently, the In/p-Si/n-Er _2 O _3 /In device demonstrated significant BBPD properties– low I _dark ∼0.15 μ A (at +5 V), photo-to-dark current ratio (PDCR) ∼6.5 (at +5 V, 700 nm) with a maximum photoresponsivity ∼22.3 A W ^−1 , and impressive detectivity (∼10 ^13 Jones) even in UV-C region where traditional silicon-based photodetectors respond feebly. The device also demonstrates transient photo-response across an ultrawide spectrum (254 nm–1200 nm) with a fast rise time/fall time ∼79 ms/∼86 ms (at −5 V for 600 nm illumination). This work establishes a straightforward and reliable method for proper material engineering, surface texturing, staggered heterojunction formation, and high-performance BBPD fabrication with prominent broad-spectrum responsivity, sizeable detectivity, and fast response. The integration of these BBPDs with Silicon opens possibilities for their use in electronic devices containing optical switches for communications and broadband image sensors, enhancing their utility in various applications.

Broadband optoelectronics, which extend from the UV to IR regions, are crucial for imaging, autonomous driving, and object recognition. In particular, photon detection efficiency relies significantly on semiconductor properties, such as absorption coefficients and electron-hole pair generation rate, which can be optimized by designing a suitable p-n junction. In this study, we devise giant PbS colloidal quantum dots (G-PbS CQDs) that exhibit high absorption coefficients and broadband absorption. To leverage these exceptional optical properties, we combine G-PbS CQDs with an ultrawide-bandgap semiconductor, α-Ga 2 O 3 , and create an efficient G-PbS CQD/α-Ga 2 O 3 heterojunction photodetector that exhibits high performance across the UVC-vis-NIR spectrum range. The resultant heterojunction facilitates efficient electron-hole pair separation at the G-PbS CQD/α-Ga 2 O 3 heterojunction. Furthermore, we utilize transparent graphene electrodes to overcome the limitations of conventional transistor-type device structures and the substantial optical losses induced by opaque metal electrodes. This strategy maximizes the light-collection area and results in an approximately 3-orders of magnitude higher responsivity (55.5 A/W) and specific detectivity (1.66 × 10 13 Jones) compared to devices with opaque metal electrodes.

To expand the detection capabilities of silicon (Si)-based photodetector and address key scientific challenges such as low light absorption efficiency and short carrier lifetime in Si-based graphene photodetector. This work introduces a novel Si-based Schottky coupled structure by in situ growth of 3D-graphene and molybdenum disulfide quantum dots (MoS 2 QDs) on Si substrates using chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques. The findings validate the "dual-enhanced absorption" effect, enhancing the understanding of the mechanisms that improve optoelectronic performance. The synergistic effect of 3D-graphene's natural nano-resonant cavity and MoS 2 QDs enhances light absorption efficiency and extends carrier lifetime. Introducing MoS 2 QDs broadens and intensifies the built-in electric field, promoting the separation of photogenerated electrons and holes. The photodetector exhibits a wideband light response in the wavelength range of 380-2200 nm. It stably outputs photocurrent under high-frequency (1 kHz) modulated laser (2200 nm), with a responsivity (R) of 40 mA W -1 and detectivity (D * ) of 1.15 × 10 9 Jones. Photodetectors show the ability to process and encrypt complex binary signals and achieve versatility in "AND" gate and "OR" gate logic operations, as well as image sensing (240 × 200 pixels)., (© 2024 Wiley‐VCH GmbH.)

Silicon-based conventional photodetectors have always been a vital part of many electronic and optoelectronic circuits because of their low fabrication cost, high device performance, and simple configuration. However, due to the relatively poor light–matter interaction and narrow bandgap in Si, these photodetectors generally suffer from a certain compromise in their photoresponsivity as well as broadband photoresponse. Here, a novel approach of coupling reduced-graphene oxide (rGO) decorated $\beta $ -In2S3 with Si has been demonstrated. $\beta $ -In2S3 thin film has been grown by a direct and transfer-free method on Si substrate and rGO has been drop-casted on $\beta $ -In2S3. This introduction of a double-heterojunction architecture results in a photoresponsivity of ~30.41 A/W at 625 nm at an applied voltage of −4 V with the response and recovery times of 60 and $40 ~\mu \text{s}$ , respectively, along with a broadband response in the wavelength range of 400–1200 nm. The rGO acts as an efficient hole transporting layer, which readily reduces the recombination of the photogenerated electrons and holes, leading to high photoresponse. These results highlight a simple and cost-effective strategy to construct high-performance broadband photodetectors, which can be useful in future optoelectronic devices. [ABSTRACT FROM AUTHOR]

• Photodetector based on graphene-core/shell QDs hybrid heterostructure was prepared. • The devices exhibit a broad photoresponse to the light ranging from 365 to 1250 nm. • The devices have higher photosensitivity and higher detectivity than that of usual. • The core/shell devices lifetime was 9 times greater than that of uncoated devices. Photodetectors based on PbSe quantum dots (QDs) are commonly used for light detection in the near-infrared (NIR) region. Nevertheless, the performance of photodetectors based on PbSe QDs is constrained by ineffective carrier transfer and poor photo and thermal stabilities. Herein, a promising strategy that harnesses PbSe/PbS core/shell QDs structures is developed and demonstrated to enhance the long-term stability of photodetectors, further combining with graphene to form hybrid heterojunctions that effectively promote carrier transfer. As a result, the devices exhibit a broad photoresponse to the incident light at range of 365–1250 nm, and also possess a high photosensitivity of 1.5 × 104 A/W and a high detectivity of 4.0 × 1013 Jones. Moreover, the lifetime of graphene-PbSe/PbS core/shell QDs hybrid photodetector was 9 times greater than that of uncoated QDs devices. The enormous boost might be attributed to the passivation and protection provided by the core–shell structure, and graphene's efficient extraction of charge carriers. [ABSTRACT FROM AUTHOR]

• We present the successful fabrication of a novel photodetector based on a 2D perovskite/Si heterojunction. • The fabricated device exhibits an exceptional responsivity of 3.53 A/W for 850 nm radiation, surpassing the typical few mA/W responsivities achieved by a majority of previously reported perovskite-based vertical photodetectors. • The device shows a rapid response of approximately 25.9 μs. Quasi-2D perovskites have gained significant attention as promising two-dimensional materials for optoelectronic applications. They offer unique optical and electrical properties as well as enhanced stability compared to their 3D counterparts. In this study, we present the successful fabrication of a novel photodetector based on a BA 2 MAPb 2 I 7 /Si heterojunction. The optoelectronic properties of the BA 2 MAPb 2 I 7 /Si-based photodetector demonstrate its high sensitivity across a broad range of incident wavelengths spanning from 365 nm to 850 nm. Notably, the fabricated device exhibits an exceptional responsivity of 3.53 A/W for 850 nm radiation, surpassing the typical few mA/W responsivities achieved by a majority of previously reported perovskite-based vertical photodetectors. Furthermore, the device shows a rapid response of approximately 25.9 μs. These results highlight the potential of our fabrication approach to realize highly sensitive broadband photodetectors using a simple and cost-effective process, making them suitable for integration with Si-based electronics. [ABSTRACT FROM AUTHOR]

Alkali metal vapor was applied as sensitive frequency-conversion photodetectors, however, their application was limited by their natural narrow (∼100 MHz) sensing frequency range. Here, Cs–Xe excimer is used to break this limitation. Demonstration of Cs–Xe frequency up-conversion photodetector is given. Using excimer transition, 550–552 nm light is converted to 541 nm fluorescence, this conversion wavelength band is much larger than a typical atom energy level transition. The frequency up-conversion background is mainly energy pooling fluorescence, which varies with Cs 6P 3/2 state number density on roughly a cubic function. Atom collision generated Cs 12D J , 9F J levels are measured and discussed. By switching excimer transitions selected, e.g. using Cs nP J (n = 7, 8, ...) related upward excimer transitions, it is possible to detect light with other wavelength from infrared to terahertz band. The concept in this work may get application in photon detection with high sensitivity. • Cesium xenon excimer realizes broadband thresholdless photon frequency conversion. • Excimer spectra are compared with cesium atom-only situation to reveal kinetics. • Noise level in the photon frequency conversion is studied and management is given. [ABSTRACT FROM AUTHOR]

Photodetectors with considerably high performance working in a wide wavelength range extending from UV to IR are essential for technological applications. The present work primarily focuses on the multilayer structure of Ge/Sn/Al 2 O 3 deposited on Si substrate for visible to short wave infrared (SWIR) broadband photodetector applications. The synthesis of a multilayered structure was carried out using electron beam evaporation. Subsequently, these samples were subjected to rapid thermal annealing (RTA). The crystalline nature of films after RTA was examined using X-ray diffraction, and Raman spectroscopy. Afterward, the photodetector measurements were carried out on the fabricated device. The device structure shows better responsivity, external quantum efficiency, detectivity, and noise equivalent power with varying optical power and voltage. The measured responsivity, external quantum efficiency, and detectivity are 1.07 A/W, 125 %, and 2.1 × 109 Jones, respectively. The results indicated the possibility of using the Ge/Sn/Al 2 O 3 multilayered structure as visible to SWIR photodetector. • Multilayer structure of Ge, Sn, and Al 2 O 3 was synthesized using e-beam evaporation. • Heterostructure photodetector shows broadband photoresponse in UV-to-SWIR region. • Synthesized multilayer photodetector exhibits high responsivity. [ABSTRACT FROM AUTHOR]

Integration of nanolayered metal chalcogenides with wide-bandgap semiconductors forming pn heterojunction leads to the way of high-performance photodetection. This work demonstrates the fabrication of a few nanometer thick Molybdenum diselenide (MoSe2)/Mg-doped Gallium Nitride (p-GaN) heterostructure for light detection purposes. The device exhibits low noise broadband spectral response from ultraviolet to near-infrared range (300â€"950 nm). The band-alignment and the charge transfer at the MoSe2/p-GaN interface promote self-powered photodetection with high photocurrent to dark current ratio of 2000 and 1000 at 365 nm and 640 nm, respectively. A high responsivity of 130 A Wâˆ'1, detectivity of 4.8 × 1010 Jones, and low noise equivalent power of 18 fW/Hz1/2 at 365 nm is achieved at an applied bias of 1 V. Moreover, the transient measurements reveal a fast rise/fall time of 407/710 ÎĽ sec for the fabricated device. These outcomes exemplify the viability of MoSe2/p-GaN heterostructure for high-speed and low-noise broadband photodetector applications. [ABSTRACT FROM AUTHOR]

Broadband photodetectors have driven the development of optical communication, image sensing, and health monitoring technologies, yet confronting a challenge in acquiring high performance in the whole spectral range. Herein, a novel low‐bandgap platinum(II)‐acetylide conjugated polymer is designed and synthesized by introducing near‐infrared‐absorbing aza‐BODIPY moieties. Benefiting from the good solubility and extended conjugated systems, it can serve as the donor materials for photodetector. By blending with (6,6)‐phenyl‐C61‐butyric acid methyl ester, organic bulk heterojunction photodetectors are successfully constructed, exhibiting a high detectivity over 1011 Jones in a broad band of 330–930 nm. Especially, the photodetector exhibits external quantum efficiency mostly beyond 15% in the NIR region. This work opens a new possibility for high‐performance organic broadband photodetector application. [ABSTRACT FROM AUTHOR]

Conventional heterojunction photodetectors rely on planar junction architecture which suffer from low interfacial contact area, inferior light absorption characteristics and complex fabrication schemes. Heterojunctions based on mixed dimensional nanostructures such as 0D-1D, 1D-2D, 1D-3D etc have recently garnered exceptional research interest owing to their atomically sharp interfaces, tunable junction properties such as enhanced light absorption cross-section. In this work, a flexible broadband UVâ€"vis photodetector employing mixed dimensional heterostructure of 1D NiO nanofibers and 3D Fe2O3 nanoparticles is fabricated. NiO nanofibers were synthesized via economical and scalable electro-spinning technique and made composite with Fe2O3 nanoclusters for hetero-structure fabrication. The optical absorption spectra of NiO nanofibers and Fe2O3 nanoparticles exhibit peak absorption in UV and visible spectra, respectively. The as-fabricated photodetector displays quick response times of 0.09 s and 0.18 s and responsivities of 5.7 mA Wâˆ'1 (0.03 mW cmâˆ'2) and 5.2 mA Wâˆ'1 (0.01 mW cmâˆ'2) for UV and visible spectra, respectively. The fabricated NiOâ€"Fe2O3 device also exhibits excellent detectivity in the order of 1012 jones. The superior performance of the device is ascribed to the type-II heterojunction between NiOâ€"Fe2O3 nanostructures, which results in the localized built-in potential at their interface, that aids in the effective carrier separation and transportation. Further, the flexible photodetector displays excellent robustness when bent over ∼1000 cycles thereby proving its potential towards developing reliable, diverse functional opto-electronic devices. [ABSTRACT FROM AUTHOR]

Leveraging the unique physical properties, two-dimensional (2D) materials have circumvented the disadvantages of conventional epitaxial semiconductors and held great promise for potential optoelectronic applications. So far, two main detector architectures including photodiode based on a van der Waals P-N junction or Schottky junction and phototransistor based on individual 2D materials or hybrids have been well developed. However, a trade-off between responsivity and speed always exists in those technologies thus hindering the overall performance improvement. Here, we propose a new device concept by sandwiching the 2D anisotropic semimetal between p-type and n-type semiconductors in the out-of-plane direction, called PSN architecture, realizing the improvement of each parameter including broad spectral coverage, fast speed, high sensitivity, power-free and polarization-sensitive. We stack the p-type 2H-MoTe2, Weyl semimetal 1T-MoTe2 and n-type SnSe2 layer-by-layer constructing vertical sandwich structure where the top and bottom layers contribute to the internal built-in electric field, the intermediate layer can facilitate the exciton dissociation and act as infrared polarized light sensitizers. As a result, this PSN device exhibits broadband photo-response from 405 to 1,550 nm without external bias supply. At optical communication band (1,310 nm), operating at self-driven mode and room temperature, the responsivity and detectivity can reach up to 64.2 mA·W−1 and 2.2×1011 Jones, respectively, along with fast speed on the order of millisecond. Moreover, the device simultaneously exhibits exceptional detection capability for infrared polarized light, demonstrating the anisotropic photocurrent ratio of 1.55 at 1,310 nm and 2.02 at 1,550 nm, which is attributed to the strong in-plane optical anisotropy of middle 1T-MoTe2 layer. This work develops a new photodetector scheme with novel PSN architecture toward broadband, self-power, polarized light sensing and imaging modules. [ABSTRACT FROM AUTHOR]

In this work, an In0.53Ga0.47As/GaAs0.5Sb0.5 type-II superlattice(T2SL) based broadband photodetector with an optical spectrum response ranging from 250 nm to 2400 nm is demonstrated. The photodetector shows a low dark current density of $3.48\times 10^{-4}$ A/cm2 under the bias of −1 V and a specific detectivity (D*) of $1.59\times 10^{10}$ cm $\cdot $ Hz1/2/W at $2 ~\mu \text{m}$ at 293 K. A recessed window on the surface of the top P layer was fabricated to enhance the responsivity of ultraviolet (UV) and visible band. The UV and visible band quantum efficiency (QE) can increase by 40% with the recessed window. [ABSTRACT FROM AUTHOR]

In this paper, a glioblastoma cancer cell biosensor is proposed based on mono-layer graphene/(n-type)Si Schottky junction. Human fibroblast cells are used as a control to study the behavior of the sensor in the presence of healthy cells. It is shown that in the presence of two different glioblastoma cancer cell lines (U87 and T98G) and human fibroblast cells, the photoconductivity of this junction drastically changes under illumination with different wavelengths of light (380 nm to 850 nm). The relative change in photoconductivity of the sensor can not only distinguish the two glioblastoma cancer cell lines, but can also easily differentiate these cancer cells from healthy human fibroblast cells. The proposed sensor is cheap and easily fabricated, and can open a new avenue for detection and differentiation of cancer cells. [ABSTRACT FROM AUTHOR]

The limitations of two-dimensional (2D) graphene in broadband photodetector are overcome by integrating nitrogen (N) doping into three-dimensional (3D) structures within silicon (Si) via plasma-assisted chemical vapor deposition (PACVD) technology. This contributes to the construction of vertical Schottky heterojunction broad-spectrum photodetectors and applications in logic devices and image sensors. The natural nanoscale resonant cavity structure of 3D-graphene enhances photon capture efficiency, thereby increasing photocarrier generation. N-doping can fine-tune the electronic structure, advancing the Schottky barrier height and reducing dark current. The as-fabricated photodetector exhibits exceptional self-driven photoresponse, especially at 1550 nm, with an excellent photoresponsivity (79.6 A/W), specific detectivity (10 13 Jones), and rapid response of 130 μs. Moreover, it enables logic circuits, high-resolution pattern image recognition, and broadband spectra recording across the visible to near-infrared range (400-1550 nm). This research will provide new views and technical support for the development and widespread application of high-performance semiconductor-based graphene broadband detectors.

As p-type phase-change degenerate semiconductors, crystalline and amorphous germanium telluride (GeTe) exhibit metallic and semiconducting properties, respectively. However, the massive structural defects and strong interface scattering in amorphous GeTe films significantly reduce their performance. In this work, two-dimensional (2D) p-type GeTe nanosheets are synthesized via a specially designed space-confined chemical vapor deposition (CVD) method, with the thickness of the GeTe nanosheets reduced to 1.9 nm. The space-confined CVD method improves the crystallinity of ultrathin GeTe by lowering the partial pressure of the reactant gas, resulting in GeTe nanosheets with excellent p-type semiconductor properties, such as a satisfactory on/off ratio of 10 5 . Temperature-dependent electrical measurements demonstrate that variable-range hopping and optical-phonon-assisted hopping mechanisms dominate transport behavior at low and high temperatures, respectively. GeTe devices exhibit significantly high responsivity (6589 and 2.2 A W -1 at 633 and 980 nm, respectively) and detectivity (1.67 × 10 11 and 1.3 × 10 8 Jones at 633 and 980 nm, respectively), making them feasible for broadband photodetectors in the visible to near-infrared range. Furthermore, the fabricated GeTe/WS 2 diode exhibits a rectification ratio of 10 3 at zero gate voltage. These satisfactory p-type semiconductor properties demonstrate that ultrathin GeTe exhibits enormous potential for applications in optoelectronic interconnection circuits., (© 2024 Wiley‐VCH GmbH.)

Surface plasmons of metal nanostructures can resonantly enhance the light absorption of two-dimensional (2D) materials and stacked van der Waals (vdW) heterostructure-based photodetectors, realizing the improvement of responsivity. So far, it has remained challenging to control and tune surface plasmons via artificially varying the geometry of arrayed metal nanostructures. Here, we demonstrate a broadband plasmonic photodetector based on an integration of gold nanoparticles (Au NPs) on a WSe2/MoS2 vdW heterostructure. The plasmon resonance peaks could be tuned by the artificially patterning of Au NPs with the geometry controlled by a rapid thermal processing technique and enable a great improvement of light absorption crossing broadband spectral regimes from 400 to 1100 nm. Our device operates at room temperature and exhibits the highest responsivity of up to 1948 mA W–1, detectivity of 7.2 × 1011 cm Hz1/2 W–1, and the ultrafast response of 8.3 μs under an illumination with zero-bias voltage. These merits of high-performance detection and rapidly scalable production of controlled metal nanostructures, with the development of 2D material synthesis and transfer techniques, offer great potential for large-area and smart fabrication of nanoscale optoelectronic devices with low power consumption. [ABSTRACT FROM AUTHOR]

Due to weak light-matter interaction, standard chemical vapor deposition (CVD)/exfoliated single-layer graphene-based photodetectors show low photoresponsivity (on the order of mA/W). However, epitaxial graphene (EG) offers a more viable approach for obtaining devices with good photoresponsivity. EG on 4H–SiC also hosts an interfacial buffer layer (IBL), which is the source of electron carriers applicable to quantum optoelectronic devices. We utilize these properties to demonstrate a gate-free, planar EG/4H–SiC-based device that enables us to observe the positive photoresponse for (405–532) nm and negative photoresponse for (632–980) nm laser excitation. The broadband binary photoresponse mainly originates from the energy band alignment of the IBL/EG interface and the highly sensitive work function of the EG. We find that the photoresponsivity of the device is > 10 A/W under 405 nm of power density 7.96 mW/cm2 at 1 V applied bias, which is three orders of magnitude greater than the obtained values of CVD/exfoliated graphene and higher than the required value for practical applications. These results path the way for selective light-triggered logic devices based on EG and can open a new window for broadband photodetection. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper reports a photoconductive type (Ag/Cu2SnS3(CTS) QDs/Ag) Vis-NIR photodetector having small channel spacing ($\sim 63.3 \boldsymbol {\mu }\text{m}$) on glass substrate. The low cost solvothermal processed CTS QDs have been used as carrier transporter as well as broad light absorber. The optical parameters of the proposed structure for small illumination power density have been calculated for broad range light illumination wavelengths (650-1100 nm). The responsivity of device was found to be ~37 (mA/W) for visible (730 nm) and ~67 (mA/W) for NIR (940 nm) illumination wavelengths. The sensitivity of the device was observed to be ~2.28 and ~8.2 for 730 and 940 nm illumination wavelengths, respectively, at 5V. The time response of the device have been measured under Vis-NIR illumination and found to be ~0.96 s (rise time) and ~1.29 s (fall time). [ABSTRACT FROM AUTHOR]

Photodetectors with broadband response spectrum have attracted great interest in many application areas such as imaging, gas sensing, and night vision. Here, a high performance broadband photodetector is demonstrated with inorganic perovskite CsPbBr3/GeSn heterojunction, detection range can be covered from 450 to 2200 nm. The responsivity of heterojunction device can achieve as high as 129 mA W−1 under illuminated light of 532 nm, which is 4.92 times larger than that of a GeSn based device. As the CsPbBr3 can also act as anti‐reflective coating for infrared wavelength, the infrared band responsivity at wavelength of 2200 nm can also be raised by 1.42 times. In addition, the device with all inorganic components is showed good stability, while keeping in the dry environment, the device can sustain its 90% original after 550 h storage. These results show the inorganic perovskite/GeSn heterojunction device is of great potential in broadband photodetection with high responsivity. [ABSTRACT FROM AUTHOR]