High-performance Broadband Photodetectors Research Articles

Strong Covalent Coupling in Vertically Layered SnSe2/PTAA Heterojunctions Enabled High Performance Inorganic-Organic Hybrid Photodetectors.

Controllable large-scale integration of two-dimensional (2D) materials with organic semiconductors and the realization of strong coupling between them still remain challenging. Herein, we demonstrate a wafer-scale, vertically layered SnSe2/PTAA heterojunction array with high light-trapping ability via a low-temperature molecular beam epitaxy method and a facile spin-coating process. Conductive probe atomic force microscopy (CP-AFM) measurements reveal strong rectification and photoresponse behavior in the individual SnSe2 nanosheet/PTAA heterojunction. Theoretical analysis demonstrates that vertically layered SnSe2/PTAA heterojunctions exhibit stronger C-Se covalent coupling than that of the conventional tiled type, which could facilitate more efficient charge transfer. Benefiting from these advantages, the SnSe2/PTAA heterojunction photodetectors with an optimized PTAA concentration show high performance, including a responsivity of 41.02 A/W, an external quantum efficiency of 1.31 × 104%, and high uniformity. The proposed approach for constructing large-scale 2D inorganic-organic heterostructures represents an effective route to fabricate high-performance broadband photodetectors for integrated optoelectronic systems.

Uncooled Broadband Photodetection via Light Trapping in Conformal PtTe2-Silicon Nanopillar Heterostructures.

Dirac semimetals have demonstrated significant attraction in the field of optoelectronics due to their unique bandgap structure and high carrier mobility. Combining them with classical semiconductor materials to form heterojunctions enables broadband optoelectronic conversion at room temperature. However, the low light absorption of layered Dirac semimetals substantially limits the device's responsivity in the infrared band. Herein, a three-dimensional (3D) heterostructure, composed of silicon nanopillars (SiNPs) and a conformal PtTe2 film, is proposed and demonstrated to enhance the photoresponsivity for uncooled broadband detection. The light trapping effect in the 3D heterostructure efficiently promotes the interaction between light and PtTe2, while also enhancing the light absorption efficiency of silicon, which enables the enhancement of the device responsivity across a broadband spectrum. Experimentally, the PtTe2-SiNPs heterojunction device demonstrates excellent photoelectric conversion behavior across the visible, near-infrared, and long-wave infrared (LWIR) bands, with its responsivity demonstrating an order-of-magnitude improvement compared to the counterparts with planar silicon heterojunctions. Under 11 μm laser irradiation, the noise equivalent power (NEP) can reach 1.76 nW·Hz-1/2 (@1 kHz). These findings offer a strategic approach to the design and fabrication of high-performance broadband photodetectors based on Dirac semimetals.

Environmental-Friendly Ag2S QD-Multilayer MoSe2 van Der Waals Heterostructure for High-Performance Broadband Photodetection.

Broadband photodetectors have drawn intensive attention owing to their wide application prospects in optical communication, imaging, astronomy, and so on. Two-dimensional transition-metal dichalcogenides (TMDs) are considered as highly potential candidates for photodetection applications, benefiting from their excellent photoelectric properties. However, most of the photodetectors based on TMDs suffer from low performance in the near-infrared (NIR) region due to the weak optical absorption efficiency near their absorption band edge, which severely constrains their usage for broadband optoelectronics. Here, by taking advantage of the high absorption coefficient and environment-friendly property of Ag2S quantum dots (QDs), the hybrid of multilayer MoSe2/Ag2S QDs is demonstrated with a high-performance broadband photodetection capability (532-1270 nm). The favorable energy band alignment of MoSe2/Ag2S QDs facilitates effective separation and collection of photogenerated carriers, and the heterostructure device exhibits significant enhancement of performance compared to the bare MoSe2 device. High responsivity, detectivity, and external quantum efficiency of 25.5 A/W, 1.45 × 1011 Jones, and 1070% are obtained at a low working voltage of 1 V under 980 nm illumination. The responsivity of the device can reach up to 1.2 A/W at 1270 nm wavelength, which is competitive to the commercial NIR photodetectors. Meanwhile, broadband imaging capability is demonstrated. Our work may open up a facile and eco-friendly approach to construct high-performance broadband photodetectors for next-generation compact optoelectronic applications.

Self-Powered Broadband Photodetector Based on NiO/Si Heterojunction Incorporating Graphene Transparent Conducting Layer.

In this study, a self-powered broadband photodetector based on graphene/NiO/n-Si was fabricated by the direct spin-coating of nanostructured NiO on the Si substrate. The current-voltage measurement of the NiO/Si heterostructure exhibited rectifying characteristics with enhanced photocurrent under light illumination. Photodetection capability was measured in the range from 300 nm to 800 nm, and a higher photoresponse in the UV region was observed due to the wide bandgap of NiO. The presence of a top graphene transparent conducting electrode further enhanced the responsivity in the whole measured wavelength region from 350 to 800 nm. The photoresponse of the NiO/Si detector at 350 nm was found to increase from 0.0187 to 0.163 A/W at -1 V with the insertion of the graphene top layer. A high photo-to-dark current ratio (≃104) at the zero bias indicates that the device has advantageous application in energy-efficient high-performance broadband photodetectors.

Self-Assembled BiGaSeAs Composite Superlattice-Structured Nanowire for Broad-Band Photodetection.

Photodetectors with a broad-band response range are widely used in many fields and are regarded as pivotal components of the modern miniaturized electronics industry. However, commercial broad-band photodetectors composed of traditional bulk semiconductor materials are still limited by complex preparation techniques, high costs, and a lack of mechanical strength and flexibility, which are difficult to satisfy the increasing demand for flexible and wearable optoelectronics. Therefore, researchers have been devoted to finding new strategies to obtain flexible, stable, and high-performance broad-band photodetectors. In this work, a novel self-assembled BiGaSeAs composite superlattice-structured nanowire was developed with a simple chemical vapor deposition method for easy fabrication. After the device assembling, the photodetector showed outstanding performance in terms of obvious Ion/Ioff (13.9), broad-band photoresponse (365-940 nm), excellent responsivity (1007.67 A/W), high detectivity (9.38 × 109 Jones), and rapid response (21 and 23 ms). The formation of microheterojunctions among various materials inside the nanowires also contributed to their extended broad-spectrum response and outstanding detection ability. These results indicate that the BiGaSeAs nanowires have potential applications in the field of flexible and wearable electronics.

High-performance broadband photodetector based on PtSe2/MoS2 heterojunction from visible to near-infrared region

High-performance broadband photodetector based on PtSe2/MoS2 heterojunction from visible to near-infrared region

Fabrication of Sb2Se3-based high-performance self-powered Visible-NIR broadband photodetector

Fabrication of Sb2Se3-based high-performance self-powered Visible-NIR broadband photodetector

A high-performance self-powered broadband photodetector based on vertical MAPbBr3/ZnO heterojunction

A high-performance self-powered broadband photodetector based on vertical MAPbBr3/ZnO heterojunction

Sm, Pt asymmetric n- and p-type contacts in WSe2 phototransistor for high-performance broadband photodetection

The development of high-performance broadband photodetectors working at room temperature is still attractive. The Schottky barrier phototransistor based on asymmetric junction seems to be endowed with such potential—as photodetectors with low device power consumption and high photoresponse; however, it is rarely studied. Herein, a Sm–WSe2–Pt phototransistor with asymmetric metal contacts is constructed, and it is systematically investigated for their electronic and photoelectronic tunability via gate voltage, wavelength, and illumination power density. It was found that the tunable photogating process dominates the photoresponse mechanism, which allows for an excellent broadband photodetection from 300 to 1000 nm wavelength. In addition, the responsivity (R) and specific detectivity (D*) at 450 nm can reach 1723 A/W and 2.3 × 1013 Jones, respectively, while that of infrared illumination of 900 nm can reach 4.7 A/W and 3.1 × 1010 Jones, respectively. In addition, the device exhibits obvious photoresponse at zero bias, the R and D* can reach up to 27 mA/W and 8.5 × 1010 Jones, which realizes self-driven photodetection. This work provides an optimal option for realizing high-integrated, high-performance, low-power-consuming, and room-temperature-working broadband photodetectors.

Carrier-recirculating broadband photodetector with high gain based on van der Waals In2Se3/MoS2 heterostructure

Two-dimensional (2D) materials present enormous potential in photoelectric detection, medical imaging, and neuromorphic vision applications due to their superior electronic and optoelectronic properties. Nevertheless, the photoelectric performance is restricted by the short lifetime of photogenerated carriers and weak optical absorption attributed to the atomic-scale thickness. This work demonstrates a novel high-gain photodetector based on van der Waals β-In2Se3/MoS2 heterostructure induced by carrier recirculation. In this structure, the photoexcited holes are trapped in the charge traps of MoS2 driven by the built-in electric field, which suppresses the recombination of photogenerated carriers, thus the electrons are repeatedly recycled across the In2Se3 channel after the generation of electron-hole pairs, achieving the high optical gain of 2.95 × 103. The responsivity, external quantum efficiency and specific detectivity of In2Se3/MoS2 photodetector can reach 616.77 A/W, 125900 %, and 1.03 × 1012 Jones at 638 nm, respectively, which are significantly higher than those of individual In2Se3 and MoS2 photodetector. More significantly, due to the enhanced optical absorption and interlayer transition, the photoresponse spectrum of In2Se3/MoS2 heterojunction is further extended to 1310 nm, which can be applied to broadband photodetection. Therefore, the In2Se3/MoS2 vdWs heterojunction photodetector provides a feasible approach to fabricate high-performance broadband photodetectors.

High performance broadband photodetector in two-dimensional metal dichalcogenides mediated by topologically protected surface state

Carrier scattering in photodetectors employing 2D dichalcogenide as an absorber impedes carrier transport. As scattering at the interface between the semiconductor and the electrode restricts carrier transport, it is essential to develop alternative electrode materials to achieve high photoresponsivity. A carrier can effectively move through a topologically protected Dirac surface state without scattering: i.e., alternatives such as topological insulators (TI) containing the surface state can effectively reduce scattering at the interface between the semiconductor and the electrode. In this stucy, TI Bi2Se3 with a well-ordered interfacial structure was used as a carrier transport layer (CTL) to effectively employ the topological surface state (TSS) for improving WSe2 photoresponsivity. At 520 nm, the Bi2Se3 TI-CTL photodetector has a photoresponsivity of up to 11.47 AW−1, 100 times higher than the photodevice using only Au electrodes. The photoresponsivity and time-resolved photoluminescence as a function of thickness indicate that TSS contributes to improved carrier separation with high carrier transfer efficiency, thereby affecting photocurrent generation. The fast carrier transfer through TSS helps efficiently separate electron-hole pairs and suppress recombination at the interface, generating ultra-fast and high-efficiency photocurrents in the broadband region (450–1550 nm). Therefore, TSS based on carrier dynamics can lead to further applications of next-generation optoelectronic devices.

High-performance broadband photodetectors based on sputtered NiOx/n-Si heterojunction diodes

High-performance broadband photodetectors based on NiOx/n-Si heterojunction were fabricated by radio frequency (rf) sputtering of NiO target at room temperature using 40, 60 and 80 W of power. The open circuit voltage is almost independent of the rf power with value of ∼0.33 V under illumination with red light with optical power of 3.71 mW/cm2, while the short circuit current depends on the sputtering power and has the highest value of 1.3 × 10−7 A (J = 1.45 × 10−3A/cm2) for diodes fabricated at 60 W. The responsivity (R) and specific detectivity in self-powered mode (Vb = 0 V) are higher for the 60 W photodiodes. The R values are 0.39, 0.61, 0.67 and 0.95 A/W under illumination with red, green, blue and UV lights with optical powers of 3.71, 1.03, 1.31 and 0.335 mW/cm2. The On/Off ratio of these diodes at Vb = 0 V is 1.5 × 104, 6.7 × 103, 9.4 × 103, 9.4 × 103 for illumination with the four lights. Capacitance-Voltage measurements indicate high quality of the NiOx/Si interface with low interface defect density and low density of bulk traps in NiOx for diodes obtained at the three powers. The responsivity of the heterojunction diodes obtained at 60 W at Vb = 0 V is among the highest reported in the literature for photodiodes based on NiOx. The quality of the rf sputtered NiOx layers and the low deposition temperature make them attractive for application in flexible optoelectronic devices.

Self-powered, thermally stable Sb2Se3-based high-performance broadband photodetector

High-performance broadband photodetectors are widely studied due to their unique significance in military and industrial applications. Vander Waals materials-based detector that simultaneously achieves a fast and high response are prerequisites for expanding the current capabilities of the optoelectronic device. Yet the thermal stability of the Vander Waals materials-based broadband (450 nm to 1250 nm) device is rarely addressed. Here, an antimony selenide (Sb2Se3) based photodetector is reported, which reveals high photo-responsivity and detectivity up to 924 mAW−1 (346 mAW−1) and 2.7 × 1010 Jones (1.0 × 1010 Jones) for the illumination wavelength 1064 nm (532 nm) under photovoltaic mode. Moreover, under 0 V-applied bias condition, the developed detector thermal stability was tested, and up to 100 °C devices disclosed a stable behavior. Further, the fabricated Sb2Se3-based broadband device was also tested under photoconductive mode. The photodetector demonstrates high responsivities of 1.5 × 104 mAW−1 (1.3 × 104 mAW−1) and 4.1 × 104 mAW−1 (3.8 × 104 mAW−1) for the illumination wavelength 532 nm and 1064 nm, respectively at room temperature (100 °C) under 0.5 V applied bias condition and 1 µW optical power. The design device can offer ideas for constructing high thermal stability and encouraging such materials in broadband photodetector applications. The state-of-the-art Sb2Se3-based detector can facilitate the translation of solution-processed optoelectronic applications from the laboratory to the marketplace.

Gapless linear dispersion in Bi2Se3 nanoparticles for high-performance broadband photodetectors

Topological insulators have demonstrated novel optoelectronic properties owing to their gapless linear dispersion and robust surface states. In this study, we implemented high-performance broadband photodetectors based on mixed-dimensional heterostructure of the topological insulator Bi2Se3 nanoparticles (NPs) with the semiconductor WSe2. Prominently, the Bi2Se3 NPs/WSe2 structure exhibited photoresponsivity of 22.17 A/W in the visible (Vis) wavelengths, and 5 A/W in the near-infrared (NIR) wavelengths and a fast response time of 40 μs. In comparison with typical semiconducting PbS NPs/WSe2 structure, we confirmed that the enhancement in the photoresponsivity, response time, and broadband photoresponse of the Bi2Se3 NPs/WSe2 structure can be attributed to the gapless behavior in surface states of topological insulator materials. Numerical simulations also confirmed a dramatic increase in the interfacial electric field by two orders of magnitude, resulting from the surface states in topological insulator NPs. The observed experimental results and the proposed mechanism pave the way for the emergence of efficient optoelectronic devices based on topological insulator materials.

Self-driven high-performance broadband photodetector based on WSe2 nano-speckles

Long-term exposure to visible or infrared light may have harmful biological consequences, such as erythema, that can damage the cornea and retina. Additionally, trapped infrared light contributes to climate change on a global scale. Self-driven broadband photodetectors, which do not need an auxiliary battery and function in a multiband region of the electromagnetic spectrum, can be the solution to monitor such radiation. Though two-dimensional (2D) materials offer excellent optoelectronic characteristics, these materials still need to be fully explored to fabricate high-performance self-driven broadband photodetector. The study proposes nano-speckles like WSe2-based self-driven photodetection that operate in a broad spectral range from vis to NIR. The developed device exhibits 2.1 mAW−1 high responsivity at 860 nm illumination at zero bias (self-driven mode). Also, at zero bias a responsivity of 1.09 mAW−1 for 532 nm light illumination and 1.05 mAW−1 for 625 nm light illumination was obtained. Further, the device shows ultra-high responsivity of 1.2 × 104 mAW−1 and a very high external quantum efficiency of 2.84 × 103% with low noise equivalent power 3.27 × 10−13 WHz−1/2 at 860 nm light illumination under photoconductive mode. This report provides a promising simple synthesis method for fabricating a self-driven photodetection device that covers vis to NIR range with high sensitivity for future optoelectronic applications.

Photovoltaic high-performance broadband photodetector based on the heterojunction of MoS2/silicon nanopillar arrays

Two-dimensional MoS2 has shown great potential in the photoelectric field because of its excellent optical and electrical properties. However, the performance of MoS2-based planar photodetector is constrained by the short transmission path and limited light absorption capacity of the planar thin layer of MoS2. In this paper, highly sensitive MoS2/silicon nanopillar arrays(Si-NPAs) photodetector by coating the surface of silicon nanotrap light array with MoS2. The interaction between light waves and silicon nanopillars and MoS2 is significantly enhanced by the Fabry-Pérot-enhanced Mie resonance between pillars as well as the multiple reflection. In the meantime, a Van der Waals heterojunction is constructed between the MoS2 and Si-NPAs coated across a large area. This is beneficial to address the poor performance of traditional two-dimensional photodetectors in light absorption and prevent the surface recombination of silicon-based photodetectors. According to the research results,the detector has 4.15 × 102 excellent rectification characteristics and 1.93 × 103 high switch ratio, and the photovoltaic effect is significant. The average external quantum efficiency of MoS2/Si-NPAs photodetector is 61.2% in the visible and near infrared bands, which is twice that of MoS2/planar silicon photodetector. At 850 nm, the responsiveness of the MoS2/Si NPAs photodetector is 0.48 A/W. the detection rate reaches 1.058 × 1012cm·Hz 1/2 W−1, which is 10.7 times higher than that of MoS2/planar silicon photodetector. To sum up, this study contributes a fresh idea to the design and application of high-performance devices.

High-performance broadband flexible photodetector based on Gd3Fe5O12-assisted double van der Waals heterojunctions

Flexible photodetectors are fundamental components for developing wearable systems, which can be widely used for medical detection, environmental monitoring and flexible imaging. However, compared with 3D materials, low-dimensional materials have degraded performance, a key challenge for current flexible photodetectors. Here, a high-performance broadband photodetector has been proposed and fabricated. By combining the high mobility of graphene (Gr) with the strong light–matter interactions of single-walled carbon nanotubes (SWCNTs) and molybdenum disulfide (MoS2), the flexible photodetector exhibits a greatly improved photoresponse covering the visible to near-infrared range. Additionally, a thin layer of gadolinium iron garnet (Gd3Fe5O12, GdlG) film is introduced to improve the interface of the double van der Waals heterojunctions to reduce the dark current. The SWCNT/GdIG/Gr/GdIG/MoS2 flexible photodetector exhibits a high photoresponsivity of 47.375 A/W and a high detectivity of 1.952 × 1012 Jones at 450 nm, a high photoresponsivity of 109.311 A/W and a high detectivity of 4.504 × 1012 Jones at 1080 nm, and good mechanical stability at room temperature. This work demonstrates the good capacity of GdIG-assisted double van der Waals heterojunctions on flexible substrates and provides a new solution for constructing high-performance flexible photodetectors.

ZnSe nanoflakes/ ZnO quantum dots heterojunction-based bandgap engineered, flexible broadband photodetector on paper substrate

ZnO-based photodetectors exhibit high responsivity and high photon absorption coefficients. However, they show absorption in a narrow range and a low photogenerated carrier lifetime, limiting their potential applications in optoelectronics. This work demonstrates a high-performance broadband photodetector using Zinc Selenide nanoflakes (ZnSe) - Zinc Oxide (ZnO) quantum dots (QDs) heterojunction. Using a simple hydrothermal method on a flexible paper substrate, this work overcomes the complexity of previously reported fabrication techniques that involve electrospinning, electron beam lithography, spin coating, etc. Detailed chemical and structural characterization reveal the formation of cubic phase of ZnSe nanoflakes-like structure showing broad absorption in the visible region. In contrast, ZnO QDs show a hexagonal structure and absorption in the ultraviolet region, improving the photodetector's detection range. The device shows superior responsivity (Rʎ) of 17.2 µA/W, and 30 µA/W, with specific detectivity (D*) of 4.74×107 Jones, and 9.39×107 Jones, for ultraviolet, and visible, respectively. Detailed studies based on energy band diagrams are performed to understand the charge transport mechanism. The device shows excellent reliability and high stability for 500 bending cycles, thus, presenting a low-cost, facile approach for developing high-performance photodetectors that find utility in wearables, healthcare, and security/defense applications.

Fast response and high-performance UV-C to NIR broadband photodetector based on MoS2/a-Ga2O3 heterostructures and impact of band-alignment and charge carrier dynamics

Recently, 2D materials have gained tremendous research interest due to their unique properties in electronics and optoelectronics. However, single 2D material-based photodetectors suffer from limitations such as narrow spectral sensitivity and slow response time due to bandgap restriction and difficulty in charge extraction. A heterojunction, which separates photo-excited electron-hole pairs and tunes absorption edge through appropriate selection of semiconductors with complementary bandgaps, is an effective strategy for broad spectral energy-conserving photodetection. This study presents a scalable 2D/3D heterostructure of MoS2/Ga2O3 with outstanding UV-C to NIR broad spectral photoresponse. The MoS2/Ga2O3 photodetector demonstrated a 315-fold increase in responsivity and EQE compared to pristine MoS2 photodetector. The device showed highest responsivity and EQE of 171 AW−1 and 2.4 × 104 % respectively under 900 nm illumination at 5 V bias. The device also exhibits high detectivity (4.6 × 1013 Jones) and fast response time of 97 µs. Moreover, the device is highly stable and shows no performance degradation over time. The device behavior was investigated through energy band diagrams and charge carrier dynamics using photoelectron spectroscopy and Kelvin probe force microscopy to gain intrinsic physical insights. The demonstration of MoS2/Ga2O3 as a high-performance broadband photodetector offers exciting opportunities for efficient optoelectronics and imaging applications.

Facile fabrication of amorphous-In2Se3/Si heterojunction for fast ultraviolet to near-infrared broadband photodetection

Indium selenide (In2Se3) has emerged as a promising candidate for broadband photodetection due to its suitable bandgap, high electron mobility, high optical absorption coefficient, and broad-spectrum absorption properties. Nevertheless, wafer-scale growth of single-component and pure-phase In2Se3 films remains challenging and requires stringent experimental parameters. Here, a facile approach for depositing amorphous-In2Se3 (a-In2Se3) on Si substrate by physical vapor deposition (PVD) process is proposed to fabricate high-performance a-In2Se3/Si heterojunction photodetectors. The as-produced devices are sensitive to a broad-spectrum (255–1300 nm), exhibiting superior overall performance with a low dark current of 0.54 nA, large current on/off ratio of 2.26 × 104, fast response with rise/decay time of 176/175 μs, decent responsivity of 1.50 A/W and detectivity of 6.46 × 1012 Jones under 1050 nm illumination at − 3 V bias. Such remarkable results can be attributed to the unique type-Ⅰ straddling energy band alignment and the strong coupling between a-In2Se3 and Si interface. In addition, decent responsivity and detectivity under 255 nm (0.29 A/W and 1.25 × 1012 Jones) and 630 nm (0.77 A/W and 3.32 × 1012 Jones) remedy the deficiency of Si in ultra-violet and visible light detection. Our work provides a facile and low-cost route for the realization of high-performance broadband photodetectors based on a-In2Se3/Si heterojunctions.