High-performance Ultraviolet Photodetectors Research Articles

High-performances ultraviolet photodetector based on vertical van der Waals heterostructures

High-performance ultraviolet (UV) photodetectors play a very important role in many fields, especially in the military, biomedical and other fields. [1]In recent years, many studies have realized ultraviolet photodetectors of 2D layered materials, overcome the problems of traditional ultraviolet detectors that are large and use high voltages. [1]Up to now, most of these works use atomically thin layers and simple p-n van der Waals (vdW) heterostructures, which have difficulty meeting the conditions of high sensitivity and ultrafast response at the same time. we report the double p-n van der Waals (vdW) heterostructure built on a large electrode. The two p-n junctions connected in parallel were proven to be able to effectively separate photo-generated carriers and suitable for ultraviolet light. This new type of photodetector exhibits competitive performance, including high R up to 254.8 A/W under UV light, and fast photoresponse τr = 7.9 μs and τd = 3.9 μs. These results provide an ideal platform for realizing highly sensitive UV photodetectors.

High performance ultraviolet photodiode based on thin DPPT-TT donor–acceptor organic polymer

A high-performance ultraviolet photodetector based on a thin layer DPPT-TT organic material is experimentally demonstrated. The high absorption of DPPT-TT in the ultraviolet band is attributed to the foundation for a high-performance ultraviolet detector. The device's responsivity can be improved by adequately designing the hole-blocking layer HfO2 and the stepped structure at the bottom contact. Due to the self-filtering and optical trapping structure, the device achieves external quantum efficiency above 100%, even with a thin absorption layer (around 50 nm). The maximum spectral responsivity of the device is 383 A/W, and the corresponding maximum specific detection rate is about 2.79 × 1012 at a bias voltage of 0.5 V. Our results advocate that the thin organic ultraviolet photodetector promises excellent potential in low-cost ultraviolet-visible light detection and imaging applications.

High-performance ultraviolet photodetector based on p-PEDOT:PSS film/p-ZnO:Sb microwire/n-Si double heterojunction

The development of high-sensitivity ultraviolet photodetectors, which can be compatible with the existing Si-based technique, is highly desirable in advanced applications. In this study, a double heterojunction ultraviolet photodetection device consisting of an ITO conductive glass covered by a layer of p-type poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer film, a single p-type Sb-doped ZnO microwire (ZnO:Sb MW), and an n-type Si substrate was proposed and demonstrated. Using dimethyl sulfoxide (DMSO) and carbon nanohorn (CNHs) as treated solvent, the electrical properties of PEDOT:PSS polymer film were positively increased. Correspondingly, the treated photodetector exhibited a strongest photoresponsivity of approximately 737.8 A/W and largest external quantum efficiency (EQE) of approximately 2.6 × 105%, which were significantly higher than those of the pristine devices. Besides, the transient response manifests its highly-stable and faster photoresponse speed of rising/falling times of ∼67 μs/2.29 ms. The enhanced photoresponse properties are attributed to the increased electrical properties of the DMSO&CNHs co-treated PEDOT:PSS film. Especially, the p-p heterojunction formed at the PEDOT:PSS/ZnO:Sb heterointerface, can effectively accelerate the transport of photogenerated electron-hole pairs, thus reducing the recombination probability. The proposed double heterojunction that meeting the criteria of low-cost and eco-friendly would be a competitive option for the large-scale fabrication of high-performance ultraviolet photodetectors, which are efficient and compatible with the existing Si-based integrated circuit technology.

Tunable electronic and optical properties of 2D SiGe/SnI2 vdW heterostructures for high-performance ultraviolet photodetectors

In this work, the structural, electronic, and optical properties of two-dimensional SiGe/SnI2 van der Waals (vdW) heterostructures (HSs) in stable configurations are investigated by using first-principles calculations. Our results show that, the honeycomb SiGe monolayer (ML) in the HSs exhibits a Dirac cone with a mini-gap, which well preserves its high carrier mobility but shows weak anisotropic electronic behaviors with respect to isolated group-IV MLs. Notably, the HSs exhibit enhanced ultraviolet (UV) absorption nearly independent of strain and strain-tunable Schottky barrier heights between the bilayers, which are desirable for Schottky UV photodetectors. In addition, the band structures and band alignments of the HSs can be tuned by fully hydrogenating SiGe ML for high-sensitivity UV detection in the infrared (IR) background. The SiGe/SnI2 HSs with tunable superior electronic and optical properties are useful for design, fabrication, and applications of high-performance UV detectors.

High performance ultraviolet A/ultraviolet C detector based on amorphous Ga2O3/ZnO Nanoarrays/GaN structure

High-performance ultraviolet (UV) photodetector was fabricated based on amorphous Ga 2 O 3 /ZnO nanoarrays(NRs) on p-GaN film. The obtained detector displays excellent UV sensing properties which covers UV-A/UV-C region with fast response without external bias. The high photosensitivity can be ascribed to the geometry of the match-like Ga 2 O 3 /ZnO NRs and emergence of the built-in field between the amorphous Ga 2 O 3 and ZnO interface. The results will provide a new method to improve the ZnO/GaN heterostructure for applications in broadband ultraviolet sensing. High-performance ultraviolet (UV) photodetector was fabricated based on amorphous Ga 2 O 3 /ZnO nanoarrays(NRs) on p-GaN film. The obtained detector displays excellent UV sensing properties which covers UV-A/UV-C region with fast response without external bias. The high photosensitivity can be ascribed to the geometry of the match-like Ga 2 O 3 /ZnO NRs and emergence of the built-in field between the amorphous Ga 2 O 3 and ZnO interface. The results will provide a new method to improve the ZnO/GaN heterostructure for applications in broadband ultraviolet sensing. • Amorphous Ga2O3/ZnO NRs/GaN photodetector were fabricated by combining aqueous method and sputtering method. • The ZnO/GaN response performance is improved by depositing amorphous Ga2O3 layer. • The device has an excellent response in the ultraviolet A and ultraviolet C regions without external bias.

Polymer Nanocomposite Graphene Quantum Dots for High-Efficiency Ultraviolet Photodetector

Influence on photocurrent sensitivity of hydrothermally synthesized electrochemically active graphene quantum dots on conjugated polymer utilized for a novel single-layer device has been performed. Fabrications of high-performance ultraviolet photodetector by depositing the polypyrrole-graphene quantum dots (PPy-GQDs) active layer of the ITO electrode were exposed to an Ultraviolet (UV) source with 265 and 355 nm wavelengths for about 200 s, and we examined the time-dependent photoresponse. The excellent performance of GQDs was exploited as a light absorber, acting as an electron donor to improve the carrier concentration. PGC4 exhibits high photoresponsivity up to the 2.33 µA/W at 6 V bias and the photocurrent changes from 2.9 to 18 µA. The electrochemical measurement was studied using an electrochemical workstation. The cyclic voltammetry (CV) results show that the hysteresis loop is optically tunable with a UV light source with 265 and 355 nm at 0.1 to 0.5 V/s. The photocurrent response in PPy-GQDs devices may be applicable to optoelectronics devices.

Ultraviolet Photodetectors Based on Polymer Microwire Arrays toward Wearable Medical Devices.

Polymer micro/nanoarchitectures have attracted intense interest for wearable medical applications due to their excellent mechanical flexibility, solution processability, and tunable optoelectronic properties. Based on polymer micro/nanostructures, high-performance ultraviolet (UV) photodetectors can not only functionalize the accurate image sensing but also sustain the biocomfortable flexible devices for real-time health monitoring. The main challenges are focused on the integration of medical wearable devices, which requires large-scale assembly of polymer micro/nanostructures with controlled morphology and strict alignment. Herein, we utilized a confined assembly system through the cautious regulation for the growth of high-quality polymer 1D arrays. UV photodetectors based on these polymer microwire arrays perform a high on/off ratio of 137 and responsivity of 19.1 mA W-1. Polymer microarray photodetectors facilitate the scale-up fabrication of 14 × 18 multiplexed image sensors for highly accurate capturing the signals of Arabic numerals "1," "2," and "3." Flexible UV photodetectors based on these arrays present excellent flexibility and bending durability, maintaining 97% of their original on/off ratio after 4000 cycles with a 10 mm bending radius. UV photodetection signals were also collected from the attached flexible devices on the back skin of the mouse, demonstrating the great potential in wearable medical photodetection.

Graphene quantum dot-sensitized GaP@ZnO nanocomposite for high-performance UV photodetectors

Zinc oxide (ZnO) has the advantages of wide bandgap, rich resources, simple preparation, and environmental friendliness, which is a type of ultraviolet (UV) detector material with great potential for development. However, the complicated preparation processes and complex device structures limit the application of ZnO UV detectors. Therefore, in this study, a high-performance UV detector was successfully fabricated based on graphene quantum dot-sensitized GaP@ZnO nanocomposite (GQDs/GaP@ZnO) thin films deposited using a simple spin-coating method. The GQDs/GaP@ZnO device exhibits higher responsivity of 142.2 A W−1, excellent detectivity of 1.1 × 1012 Jones, and a higher external quantum efficiency of 4.85 × 104% under the conditions of 365 nm UV light (0.078 mW cm−2) and external voltage of 6 V. In addition, this study provides a new research method for the preparation of high-performance optoelectronic devices using the cumulative synergistic effect of material composites and surface modification.

Sensitive Silicon Nanowire Ultraviolet B Photodetector Induced by Leakage Mode Resonances.

Ultraviolet photodetectors (UVPDs) have played an important role both in civil and military applications. While various studies have shown that traditional UVPDs based on wide-band-gap semiconductors (WBSs) have excellent device performances, it is, however, undeniable that the practical application of WBS-based UVPDs is largely limited by the relatively high fabrication cost. In this work, we propose a new silicon nanowire (Si NW) UVPD that is very sensitive to UVB light illumination. The Si NWs with a diameter of about 36 nm are fabricated by a metal-assisted chemical etching method. Performance analysis revealed that the Si NW device was only sensitive to UVB light and almost blind to illumination in the visible and near-infrared regions. Such abnormal spectral selectivity was associated with the leakage mode resonances (LMRs) of the small diameter, according to our theoretical simulation. Under 300 nm illumination, the responsivity, external quantum efficiency, and specific detectivity were estimated to be 10.2 AW-1, 4.22 × 103%, and 2.14 × 1010 Jones, respectively, which were comparable to or even higher than those of some WBS-based UVPDs. These results illustrate that the small dimension Si NWs are potential building blocks for low-cost and high-performance UVPDs in the future.

A self-powered ultraviolet photodetector based on a Ga2O3/Bi2WO6 heterojunction with low noise and stable photoresponse

A self-powered solar-blind ultraviolet (UV) photodetector (PD) was successfully constructed on a Ga2O3/Bi2WO6 heterojunction, which was fabricated by spin-coating the hydrothermally grown Bi2WO6 onto MOCVD-grown Ga2O3 film. The results show that a typical type-I heterojunction is formed at the interface of the Ga2O3 film and clustered Bi2WO6, which demonstrates a distinct photovoltaic effect with an open-circuit voltage of 0.18 V under the irradiation of 254 nm UV light. Moreover, the Ga2O3/Bi2WO6 PD displays excellent photodetection performance with an ultra-low dark current of ∼ 6 fA, and a high light-to-dark current ratio (PDCR) of 3.5 × 104 in self-powered mode (0 V), as well as a best responsivity result of 2.21 mA/W in power supply mode (5 V). Furthermore, the PD possesses a stable and fast response speed under different light intensities and voltages. At zero voltage, the PD exhibits a fast rise time of 132 ms and 162 ms, as well as a quick decay time of 69 ms and 522 ms, respectively. In general, the newly attempted Ga2O3/Bi2WO6 heterojunction may become a potential candidate for the realization of self-powered and high-performance UV photodetectors.

Enhanced performance of UV photodetector based on ZnO nanorod arrays via TiO2 as electrons trap layer

As a commonly used substrate and matrix material in the construction of high performance ultraviolet photodetector, ZnO nanorod arrays have attached much attention due to their efficiency electron transmission channels and high stability. However, they also have the problem of slow response speed inevitably. In this work, TiO2/ZnO nanorod arrays heterojunction structure was prepared and used to construct ultraviolet photodetector. The obtained heterojunction photodetector has a higher on/off ratio (>1000) and shorter rise/decay time (6.1/3.7 s) compared with that of photodetector based on ZnO nanorod arrays (on/off ratio ∼10 and decay time >20 s). The enhanced response speed is caused by the traps of the electron in TiO2 layer, which can accelerate the decay of current in the OFF state. The obtained results provide a new sight for the further development of the optoelectronic devices based on ZnO nanorod arrays in future.

High-performance self-powered UV photodetector based on CuI/CsCu2I3/GaN heterojunction

Self-powered ultraviolet (UV) photodetectors have far-reaching applications in the nanoelectronics. In this work, nontoxic copper halide perovskite CsCu2I3 thin films were grown by vacuum thermal evaporation method on n-GaN substrates. The p-CuI/CsCu2I3/n-GaN heterojunction photodetectors exhibit obvious sensitivity and self-powered characteristics in the ultraviolet (∼365 nm) narrowband. The device exhibits excellent reproducibility and a high on/off ratio of 97,886 under zero bias voltage. Furthermore, under UV illumination, the responsivity, specific detectivity, and external quantum efficiency reach 71.7 mA/W, 3.3 × 1012 Jones, and 26.1% at 0 V bias, respectively. The result provides a new strategy to design a highly integrated monolithic device for self-powered detection

Solar-blind UV photodetector with low-dark current and high-gain based on ZnO/Au/Ga2O3 sandwich structure

High performance ultraviolet photodetectors (UV PDs) have attracted significant attention due to their great potential applications in both military and civilian fields. In this work, dual-band ultraviolet PDs with two peak responses at solar blind (255 nm) and near UV (360 nm) region were successfully fabricated by constructing ZnO/Au/Ga2O3 sandwich structure. The dark current of the ZnO/Au/Ga2O3 sandwich structure PD was reduced by 35.6 times and 5.9 times in comparison with ZnO/Au and Au/Ga2O3 MSM PDs, respectively. The responsivity of the ZnO/Au/Ga2O3 PD to 255 nm light was 336.3 A/W, which is 1443 times higher than that of the Au/Ga2O3 PD and corresponds to a gain of 1637. While, the responsivity of the ZnO/Au/Ga2O3 PD to 360 nm light was 21.6 A/W, which is only 1.2 times higher than that of the ZnO/Au PD and corresponds to a gain of 73. Based on the dependence of photocurrent on incident light intensity, the suppression of dark current in the ZnO/Au/Ga2O3 PD can be attributed to the reduction of the unsaturated bonds and the trap states at the interface of ZnO and Ga2O3. The high gain at 255 nm light in the sandwiched PD has been attributed to the migration of the photogenerated hole from Ga2O3 to ZnO and the higher electron mobility and the longer hole lifetime of ZnO than that of Ga2O3. Such ZnO/Au/Ga2O3 sandwich structure PDs with low dark current and high gain hold promise for developing high performance UVA and UVC dual-band PDs.

High-performance ultraviolet photodetectors based on 2D layered In4/3P2Se6 nanoflakes

Ultraviolet photodetectors (UV PDs) based on 2D layered materials have attracted much attention because of the great applications in the fields of biology, healthcare, and space science, as well as the unique optical and electrical properties of 2D layered materials. Many UV PDs have been reported. However, high performance UV PDs with high responsivity and ultrafast light response time still need to be explored further. Here, we synthesized layered In4/3P2Se6 nanoflakes via the chemical vapor conversion (CVC) method. The UV PDs based on as-grown In4/3P2Se6 nanoflakes exhibit a very high light switching ratio of up to 6 × 105 at room temperature, which is ascribed to the large photocurrent and an ultralow dark current of ∼80 fA. Meanwhile, an ultrafast rise and a decay time of ∼ 470 μs/440 μs are achieved. The according responsivity, external quantum efficiency, and special detectivity are 4.31 A W−1, 1485.2%, and 6.3 × 1012 Jones, respectively, which are excellent performance among the UV PDs based 2D layered materials. Notably, it has both high responsivity and fast light response time, better than other 2D layered semiconductor photodetectors. Our finding demonstrates In4/3P2Se6 nanoflakes are promising materials for high performance UV PDs in the future.

Synthesis of interface modified MoS2/ZnO heterostructure via simple hydrothermal method and their enhanced UV photodetection characteristics with ultrafast photoresponse speed

Ultraviolet (UV) photodetectors employing ZnO nanorods (NRs) exhibit high photocurrent stability; however, UV photodetectors fabricated using ZnO NRs have several disadvantages. In this study, we fabricated high-performance UV photodetector using hydrothermally grown MoS2/ZnO heterostructure. The surface morphology of MoS2/ZnO heterostructure exhibited sea-urchin structure with a greater length and diameter than ZnO NRs. In addition, the formation of MoS2/ZnO heterostructure can form a type-II band alignment at interface between MoS2 and ZnO, which facilitates the regulation of electron movement with large surface area. With respect to UV photoresponse, MoS2/ZnO heterostructure exhibited a significantly improved photocurrent value compared to ZnO NRs and MoS2/ZnO heterostructure had extremely fast UV photoresponse speed with highly improved photoresponsivity, photosensitivity, and photoselectivity. Therefore, it was concluded that hydrothermally grown MoS2/ZnO heterostructure is a suitable solution to drawbacks of ZnO-based UV photodetectors; consequently, the proposed method can be used to fabricate ZnO-based high-performance optoelectronics applied in various fields.

High-performance Ultraviolet Inorganic-organic Composite Structure Photodetectors Based on Electric Field Control

High-performance Ultraviolet Inorganic-organic Composite Structure Photodetectors Based on Electric Field Control

High-Performance Self-Powered Ultraviolet Photodetector Based on Pedot:Pss/Cuo/Zno Nanorod Array Sandwich Structure

High-Performance Self-Powered Ultraviolet Photodetector Based on Pedot:Pss/Cuo/Zno Nanorod Array Sandwich Structure

High-performance self-powered visible-blind ultraviolet photodetection achieved by ferroelectric PbZr0.52Ti0.48O3 thin films

Self-powered visible-blind ultraviolet (UV) photodetection has been generally achieved based on the built-in electric field formed within the complicated devices such as pn or Schottky junctions, which involves a complicated device fabrication process. In contrast, employing the ferroelectric materials featured with unique bulk photovoltaic effect as absorbers will simplify the device structure and the subsequent device fabrication process without losing the performance of self-powered photodetection. In the current work, the fabrication of high-performance self-powered visible-blind UV photodetectors based on ferroelectric PbZr0.52Ti0.48O3 (PZT) thin films has been reported. The results showed that the spin-coated PZT thin films exhibited superior ferroelectric properties. On this basis, an efficient, stable, and repeatable self-powered UV photodetection has been achieved in the Au/PZT/FTO (fluorine-doped tin oxide) structured devices with the responsivity and detectivity as high as 0.092 A/W and 1.2 × 1012 Jones, respectively. More interestingly, the self-powered photocurrent has been further enhanced when downward polarizing the PZT thin film. The results reported in this work highlight the superiorities of ferroelectric PZT-based self-powered visible-blind UV photodetectors and provide valuable strategies for the fabrication of high-performance self-powered photodetectors with a simplified device structure in the future.

Antisolvent-Processed One-Dimensional Ternary Rubidium Copper Bromine Microwires for Sensitive and Flexible Ultraviolet Photodetectors.

Recently, newly emerging halide perovskites have aroused intensive attention in photoelectric fields in virtue of their good properties, such as well-balanced carrier transport, large light absorption coefficient, tunable band gap, and low-temperature solution processing technique. Nevertheless, their future commercial development is severely hampered by lead toxicity and instability of such materials. In this work, one-dimensional Rb2CuBr3 single-crystal microwires (MWs) were prepared by antisolvent engineering, and they were further employed as absorbers to prepare sensitive ultraviolet (UV) photodetectors. The optical band gap of Rb2CuBr3 MWs is measured to be 3.83 eV, exhibiting an excellent UV absorption. The fabricated device demonstrates a remarkable UV light detection ability with a specific detectivity of 1.23 × 1011 Jones, responsivity of 113.64 mA W-1, and response speed of 69.31/87.55 ms under light illumination of 265 nm. Meanwhile, the proposed photodetector without any encapsulation shows outstanding stability and repeatability. After storing in ambient air for 2 weeks, the light detection ability remains basically unchanged. Further, a flexible photodetector was fabricated with the same structure, which demonstrates a remarkable bending endurance. These results confirm the great potential of Rb2CuBr3 for high-performance UV photodetectors, increasing the possibility for assembly of optoelectronic systems.

Fabrication of nanostructured NiO and NiO:Cu thin films for high-performance ultraviolet photodetector

In this work, pure NiO and NiO:Cu based photodetectors with different concentrations of Cu dopants (0, 0.5,1.0, and 1.5 wt%) were coated on glass substrates by using a simple, low cost nebulizer spray pyrolysis technique. Their structural, morphological, optical (UV–Vis absorption and photoluminescence), and ultraviolet (UV) sensing features were characterized with state-of-the-art analytical techniques. The structural studies confirm that the prepared films have crystalline nature and possess a cubic structure. From the absorption measurement, the optical bandgap ( E g ) of the deposited films decreases with the increase in Cu dopants. Photoluminescence study illustrates that 1.0% of Cu doping significantly improves the physical property of the NiO:Cu films and also its UV sensing study suggests that the 1.0% of NiO:Cu film could be better suited for high-speed optoelectronic devices due to their high Responsivity (0.202 AW -1 ), External quantum efficiency (47%), and Detectivity (5.9 × 10 9 jones) values. A possible mechanism of the photodetector performance under air and UV illumination is also discussed in this work. • First time investigation on Cu insists of NiO films based UV photodetector by simple nebulizer spray method. • Reported the increase of photocurrent with respect to bias voltage for enhancing photoelectric properties. • Decrease of the optical bandgap for Cu doped films due to the observed redshift in absorption and higher crystallite size. • Maximum responsivity, external quantum efficiency, and specific detectivity were observed for the 1% Cu doped NiO detector. • A possible mechanism for enhancing photocurrent under UV illumination was also discussed with a schematic diagram.