High-performance Photodetectors Research Articles

Enhanced Performance of Self-Powered Ga2O3/ZnO:V Heterojunction Solar-Blind Ultraviolet Photodetectors by Coupling Ferroelectricity and Piezoelectricity.

Ferroelectric materials have aroused increasing interest in the field of self-powered ultraviolet (UV) photodetectors (PDs) for their switchable spontaneous polarization. However, the utilization of ferroelectric materials to modulate the built-in electric field and energy band at the junction interface has rarely been investigated. Herein, we design and fabricate self-powered solar-blind UV PDs based on a Ga2O3/ZnO:V heterojunction. The performance of the Ga2O3/ZnO:V PD is significantly enhanced through the reasonable coupling of ferroelectricity and piezoelectricity within the ZnO:V film. The device at 260 nm exhibits excellent photoelectric properties with high peak responsivity of 64.5 mA/W, a specific detectivity of 3.8 × 1010 Jones, and a rise/decay time of 1.9/45.2 μs, together with reproducibility and stability. Systematical energy band diagram analysis reveals that the excellent performance of Ga2O3/ZnO:V PD can be attributed to the driving forces arising from the addition of the depolarization field and piezoelectric field, which increases the intensity of built-in electric field and promotes the separation and transport of photogenerated carriers at the heterojunction interface. The findings of our research provide a novel avenue and valuable guidance for the design of high-performance self-powered photodetectors.

Exploiting coordination between poly (ethylene glycol) bis (carboxymethyl) ether and SnO2 for high-performance perovskite photodetectors

In perovskite detectors that utilize SnO₂ as an electron transport layer (ETL), the preparation of SnO₂ films using the solution method results in a significant number of defects. Additionally, the presence of nano-aggregates in the aqueous solution of untreated SnO₂ colloids leads to surface unevenness in SnO₂ films prepared using the spin-coating method, which can affect the growth and crystallization of perovskite. Defects and surface unevenness in SnO₂ films affect the performance of perovskite detectors. To further optimize the performance of perovskite detectors, SnO₂ incorporating poly (ethylene glycol) bis (carboxymethyl) ether (PBE) was developed, employing the polymer as a modifier. The results of the study showed that the incorporation of PBE had two effects: 1) the ether oxygen within the PBE forms a coordination bond with SnO₂, thereby reducing oxygen vacancies, and 2) reducing nano-aggregation of SnO₂ colloidal aqueous solutions, obtaining more uniform SnO₂ films, and promoting the growth and crystallization of perovskite. Ultimately, the performance of the optimized device was improved. The external quantum efficiency (EQE) improved from 84.82 % to 89.29 %, the dark current density decreased from 3.27 × 10-⁹ A cm-² to 1.03 × 10-¹⁰ A cm-², the linear dynamic range (LDR) increased from 88.5 to 118.3 dB, and the stability was enhanced. The device maintained 64.9 % of its original efficiency after being stored for 23 days at 25 °C and 20–30 % humidity.

Development of high-performance flexible photodetectors through band engineering and synergistic modulation in P3HT/C3N5 thin film

Flexible photodetectors, with applications ranging from large-scale photosensors to flexible solar cells and fiber-optical sensors, offer a promising avenue for technological advancement. Despite their high performance and stability, conventional inorganic photodetectors suffer from complex, costly manufacturing processes and lack mechanical flexibility. This gap is potentially bridged by organic semiconducting polymers (OSPs), which require enhancements in charge transport capabilities. Integrating exfoliated graphitic carbon nitride (C3N5) with OSPs, specifically into a poly(3-hexylthiophene-2,5-diyl) (P3HT) matrix, has shown to significantly improve electrical and optoelectronic properties due to C3N5's excellent optoelectronic features, adjustable bandgap, and stability. This study successfully fabricated flexible photodetectors with a P3HT/C3N5(3 %) mix in a Schottky barrier diodes (SBDs) configuration, achieving a 100-fold increase in photocurrent, exceptional flexibility, and rapid response to light. These findings highlight the potential of a synergistic approach in developing high-performance, commercially viable flexible photodetectors.

High-performance transparent AZO UV photodetectors

In this work, the fabrication of undoped ZnO (ZO) and 3 at.% aluminum (Al) doped ZnO (AZO) thin films (TFs) based transparent photodetectors (PDs) was reported. Both films were spin-coated on fluorine-doped tin oxide (FTO) substrates to investigate the influence of Al doping on the ultraviolet (UV) detection performance of the devices. The systematic characterizations reveal that Al doping positively affects the characteristics of ZO-TFs. The Al doping leads to slight shift in crystalline peaks and induces an enhancement in grain size. In addition, the surface roughness of ZO-TFs gets lower on Al doping. Further, the Al doping improved the transparency and widening of band gap of TFs. The PDs having metal–semiconductor-metal (MSM) configuration were achieved by screen-printing of Ag paste onto ZO and AZO-TFs. The current–voltage (I-V) profiles of the fabricated PDs were measured in the dark and under UV excitation of 365 nm. The AZO-TFs based MSM PD exhibits a spectral responsivity of 326.82 mA/W and an external quantum efficiency of 111.03%. The reproducibility of the fabricated PDs was tested by performing time-dependent photo-response measurements.

High Sensitive and Stable UV-Vis Photodetector Based on MoS2/MoO3 vdW Heterojunction.

The development of new high-performance photodetectors (PDs) is currently focused on achieving small size, low power consumption, low cost, and large bandwidth. Two-dimensional (2D) materials and heterostructures offer promising approaches for the future development of optoelectronic devices. However, there has been limited research on 2D wide-bandgap semiconductor heterostructures. In this study, we successfully constructed a MoS2/MoO3 vdW heterojunction PD. This PD exhibited excellent response and significant photovoltaic behavior in the ultraviolet (UV) to visible (Vis) range. Under 365 nm UV light and 1 V bias voltage, the PD demonstrated a high responsivity of 645 mA/W, a high specific detectivity of 8.98 × 1010 Jones, and fast response speeds of 55.9/59.6 ms. At 0 V bias voltage, the responsivity reached as high as 157 mA/W. Furthermore, the PD exhibited remarkable stability in its performance. These outstanding characteristics can be attributed to the strong internal electric field created by the type II heterojunction structure and the chemical stability of the materials. This work opens a route for the application of 2D wide-bandgap semiconductor materials in optoelectronic devices.

A parylene/graphene UV photodetector with ultrahigh responsivity and long term stability

Long term stability, high responsivity, and fast response speed are essential for the commercialization of graphene photodetectors (GPDs). In this work, a parylene/graphene UV photodetector with long term stability, ultrahigh responsivity and fast response speed, is demonstrated. Parylene as a stable physical and chemical insulating layer reduces the environmental sensitivity of graphene, and enhances the performances of GPDs. In addition, utilizing bilayer electrodes reduces the buckling and damage of graphene after transferring. The parylene/graphene UV photodetector exhibits an ultrahigh responsivity of 5.82 × 105 AW−1 under 325 nm light irradiation at 1 V bias. Additionally, it shows a fast response speed with a rise time of 80 μs and a fall time of 17 μs, and a long term stability at 405 nm wavelength which is absent in the device without parylene. The parylene/graphene UV photodetector possesses superior performances. This paves the way for the commercial application of the high-performance graphene hybrid photodetectors, and provides a practical method for maintaining the long term stability of two dimensional (2D) materials.

High-Performance InSe Photodetector Induced by Synergetic Surface Plasmon Resonance and Surface Engineering

High-Performance InSe Photodetector Induced by Synergetic Surface Plasmon Resonance and Surface Engineering

High performance photodetectors by integrating CsPbBr3 perovskite directly on the germanium wafer

Lead halide perovskites are a promising candidate for the development of novel optoelectronic devices. Although substantial development has been achieved after years of research, it is still a challenge to prepare large-area high-quality CsPbBr3 thin films by simple processes. In this work, CsPbBr3 film can be used as a UV–Vis absorption active layer of heterojunction photodetector and a Ge-based infrared anti-reflective coating to optimize the photodetection performance of the device. CsPbBr3/p-Ge heterojunction photodetector exhibits self-powered (0 V) and broadband characteristics (365–1550 nm), the responsivity is 64 mA/W and the specific detectivity is 1.2 × 1012 Jones under 0 V bias and 1550 nm illumination. The rise and decay times of the device are 12.3 μs and 13.4 μs under 1310 nm illumination and 20 kHz operating frequency, respectively. This work further promotes the potential application and development of CsPbBr3 perovskites in integrated optoelectronic devices.

Multifunction realization in MoS2/WS2/h-BN heterojunction: Integrated self-powered high-performance photodetection, visualization, nonvolatile memory, and synaptic simulation

Nowadays, efficient performance, functional diversification, device miniaturization and systematic integration are the trends for developing new electronic information technology. However, photodetectors with only optoelectronic detection functions cannot satisfy the growing demands of the multifunction required in single devices. This paper presents a MoS2/WS2/h-BN van der Waals heterojunction device realizing multifunctional applications which integrated self-powered high-performance photodetection, visualization, nonvolatile memory, and synaptic simulation. The heterojunction achieves a high responsivity of 9.28 A/W, an excellent specific detectivity of 6.1×1012 Jones, a large external quantum efficiency of 2358 %, a considerable on/off ratio of 7×105 and an ultrafast response time of 0.6 μs at 1 V bias under 488 nm laser irradiation. Besides, the photodetector shows excellent photovoltaic characteristics with a short-circuit current of 0.22 μA and an open-circuit voltage of 0.34 V. Moreover, the device also shows a favorable optical response to 532 and 633 nm lasers. The device also realizes visualization and can be used as an imaging sensor. In addition, the device integrates nonvolatile memory function due to the charge storage effect of h-BN and h-BN/SiO2 interface. Furthermore, biological synaptic functions, such as the memory process, short- and long-term plasticity, and double pulse facilitation, are also successfully simulated. This work realizes the high-performance and multifunctional applications of MoS2/WS2/h-BN device based on a new strategy of utilizing h-BN as a heterojunction substrate.

Plasmonically-boosted high-performance UV self-biased photodetector based on SiC-based low-dimensional heterojunction via Pt nanostructures deposition

While possessing fully superior electrical, optical and mechanical capabilities, the third-generation semiconductor SiC is extensively recognized as one of the most important candidates to developing high-temperature CMOS, intense-radiation hard detectors, high-power electron devices, and other fields. However, the fabrication of low-dimensional SiC structures presents a challenge, limiting its forward-looking applications, particularly for the miniaturized and integrated self-powered ultraviolet (UV) photodetectors. Herein, a high-performance UV photodetector, which involving a p-SiC film, a Ga-doped ZnO microwire coated by Pt nanoparticles (PtNPs@ZnO:Ga MW), a single-layer graphene (Gr) as transparent electrode, was constructed. The device exhibits pronounced UV photodetection capabilities, containing a high On/Off ratio (>105), a peak responsivity approaching 0.266 A/W, a specific detectivity exceeding 1.50 × 1013 Jones, and an exceptional external quantum efficiency closing to 98.7% upon 335 nm illumination at 0 V bias. The detector shows an admirable performance and quite competitive within their class. In the device, the surface-coated PtNPs enable to optimize ZnO:Ga/SiC interfacial performances containing significant enhancement of photoelectric conversion efficiency, efficient suppression of surface/interface defects and trapping centers, and other parameters, thus giving rise to qualitative enhancement of the overall detector properties. Simultaneously, the use of Gr electrode as transparent window allows for maximum UV light absorption and boosts transport properties for the photocarriers. This work presents a valuable reference for the development of high-performance low-dimensional SiC-based photodetecting devices, exploring an important step toward potential optoelectronic applications.

Van der Waals Schottky Junction Photodetector with Ultrahigh Rectifying Ratio and Switchable Photocurrent Generation.

Metal-semiconductor junctions play an important role in the development of electronic and optoelectronic devices. A Schottky junction photodetector based on two-dimensional (2D) materials is promising for self-powered photodetection with fast response speed and large signal-to-noise ratio. However, it usually suffers from an uncontrolled Schottky barrier due to the Fermi level pinning effect arising from the interface states. In this work, all-2D Schottky junctions with near-ideal Fermi level depinning are realized, attributed to the high-quality interface between 2D semimetals and semiconductors. We further demonstrate asymmetric diodes based on multilayer graphene/MoS2/PtSe2 with a current rectification ratio exceeding 105 and an ideality factor of 1.2. Scanning photocurrent mapping shows that the photocurrent generation mechanism in the heterostructure switches from photovoltaic effect to photogating effect at varying drain biases, indicating both energy conversion and optical sensing are realized in a single device. In the photovoltaic mode, the photodetector is self-powered with a response time smaller than 100 μs under the illumination of a 405 nm laser. In the photogating mode, the photodetector exhibits a high responsivity up to 460 A/W originating from a high photogain. Finally, the photodetector is employed for single-pixel imaging, demonstrating its high-contrast photodetection ability. This work provides insight into the development of high-performance self-powered photodetectors based on 2D Schottky junctions.

Hybrid nanocomposites for enhanced photodetection: Synthesis and application of Ag2O@Graphene/Si heterojunctions

Thin silver oxide graphene (Ag2O@G) nanocomposite films were synthesized via facile spray pyrolysis and integrated into heterojunction architectures with silicon substrate. Structural characterization confirmed the successful anchoring of crystalline Ag2O nanoparticles uniformly over graphene layers with strong interfacial coupling. Optical analysis showed synergistic tuning of the band structure by hybridization, which improves light absorption. Electrical measurements showed rectification behavior of the diode and an increase in photocurrent up to milliamperes under illumination. A response time of 350 ms, a recovery time of 400 ms, stability over repeated cycles and exceptional values such as 0.39 A/W responsivity, 88 % external quantum efficiency and 4×1011 Jones detectivity at 600 nm were achieved. The nanocomposite heterojunctions utilize the superior charge mobility of graphene with the bandgap tuning of Ag2O, enabling efficient light harvesting, photogeneration, and ambipolar charge separation and transport across the multifunctional interface. Customized Ag2O@G heterostructures represent a promising material platform to drive advances in high performance photodetectors, image sensors, night vision devices and photovoltaics through the engineering of morphology, crystallinity and interfaces.

Octupole moment driven free charge generation in partially chlorinated subphthalocyanine for planar heterojunction organic photodetectors

In this study, high-performance organic photodetectors are presented which utilize a pristine chlorinated subphthalocyanine photoactive layer. Optical and optoelectronic analyses indicate that the device photocurrent is primarily generated through direct charge generation within the chlorinated subphthalocyanine layer, rather than exciton separation at layer interfaces. Molecular modelling suggests that this direct charge generation is facilitated by chlorinated subphthalocyanine high octupole moment (−80 DÅ2), which generates a 200 meV shift in molecular energetics. Increasing the thickness of chlorinated subphthalocyanine leads to faster response time, correlated with a decrease in trap density. Notably, photodetectors with a 50 nm thick chlorinated subphthalocyanine photoactive layer exhibit detectivities approaching 1013 Jones, with a dark current below 10−7 A cm−2 up to −5 V. Based on these findings, we conclude that high octupole moment molecular semiconductors are promising materials for high-performance organic photodetectors employing single-component photoactive layer.

Transferable GeSn ribbon photodetectors for high-speed short-wave infrared photonic applications

We experimentally demonstrate a low-cost transfer process of GeSn ribbons to insulating substrates for short-wave infrared (SWIR) sensing/imaging applications. By releasing the original compressive GeSn layer to nearly fully relaxed state GeSn ribbons, the room-temperature spectral response of the photodetector is further extended to 3.2 μm, which can cover the entire SWIR range. Compared with the as-grown GeSn reference photodetectors, the fabricated GeSn ribbon photodetectors have a fivefold improvement in the light-to-dark current ratio, which can improve the detectivity for high-performance photodetection. The transient performance of a GeSn ribbon photodetector is investigated with a rise time of about 40 μs, which exceeds the response time of most GeSn (Ge)-related devices. In addition, this transfer process can be applied on various substrates, making it a versatile technology that can be used for various applications ranging from optoelectronics to large-area electronics. These results provide insightful guidance for the development of low-cost and high-speed SWIR photodetectors based on Sn-containing group IV low-dimensional structures.

Highly-Polarized Solar-Blind Ultraviolet Organic Photodetectors.

Developing high-performance polarization-sensitive ultraviolet photodetectors is crucial for their application in military remote sensing, detection, bio-inspired navigation, and machine vision. However, the significant absorption in the visible light range severely limits the application of polarization-sensitive ultraviolet photodetectors, such as high-quality anti-interference imaging. Here, based on a wide-bandgap organic semiconductor single crystal (trans-1,2-bis(5-phenyldithieno[2,3-b:3',2'-d]thiophen-2-yl)ethene, BPTTE), high-performance polarization-sensitive solar-blind ultraviolet photodetectors with a dichroic ratio close to 4.26 are demonstrated. The strong anisotropy of 2D grown BPTTE single crystals in molecular vibration and optical absorption is characterized by various techniques. Under voltage modulation, stable and efficient detection of polarized light is demonstrated, attributed to the intrinsic anisotropy of transition dipole moment in the bc crystal plane, rather than other factors. Finally, high-contrast polarimetric imaging and anti-interference imaging are successfully demonstrated based on BPTTE single crystal photodetectors, highlighting the potential of organic semiconductors for polarization-sensitive solar-blind ultraviolet photodetectors.

Unveiling the orientation growth mechanism and solar-blind response performance of β-Ga2O3 (100) film on SiC substrate with AlN buffer layer

Optimizing the orientation of β-Ga2O3 has emerged as an effective strategy to design high-performance β-Ga2O3 device, but the orientation growth mechanism and approach have not been revealed yet. Herein, by employing AlN buffer layer, the highly preferred orientation of β-Ga2O3 (100) film rather than (-201) film is realized on 4H-SiC substrate at low sputtering power and temperature. Because β-Ga2O3 (100) film exhibits a slower growth speed than (-201) film, the former possesses the higher dangling bond density and the lower nucleation energy, and a large conversion barrier exists between these two orientations. Moreover, the AlN buffer layer can suppress the surface oxidation of the 4H-SiC substrate and eliminate the strain of β-Ga2O3 (100) film, which further reduces the nucleation energy and enlarges the conversion barrier. Meanwhile, the AlN buffer layer can increase the oxygen vacancy formation energy and decrease the oxygen vacancy concentration of β-Ga2O3 (100) film. Consequently, the solar-blind photodetector based on the oriented film exhibits the outstanding detectivity of 1.22 × 1012 Jones and photo-to-dark current ratio of 1.11 × 105, which are the highest among the reported β-Ga2O3 solar-blind photodetector on the SiC substrate. Our results offer in-depth insights into the preferred orientation growth mechanism, and provide an effective way to design high-quality β-Ga2O3 (100) orientation film and high-performance solar-blind photodetector.

Self-Rolled-Up WSe2 One-Dimensional/Two-Dimensional Homojunctions: Enabling High-Performance Self-Powered Polarization-Sensitive Photodetectors.

Mixed-dimensional heterostructures integrate materials of diverse dimensions with unique electronic functionalities, providing a new platform for research in electron transport and optoelectronic detection. Here, we report a novel covalently bonded one-dimensional/two-dimensional (1D/2D) homojunction structure with robust junction contacts, which exhibits wide-spectrum (from the visible to near-infrared regions), self-driven photodetection, and polarization-sensitive photodetection capabilities. Benefiting from the ultralow dark current at zero bias voltage, the on/off ratio and detectivity of the device reach 1.5 × 103 and 3.24 × 109 Jones, respectively. Furthermore, the pronounced anisotropy of the WSe2 1D/2D homojunction is attributed to its low symmetry, enabling polarization-sensitive detection. In the absence of any external bias voltage, the device exhibits strong linear dichroism for wavelengths of 638 and 808 nm, with anisotropy ratios of 2.06 and 1.96, respectively. These results indicate that such mixed-dimensional structures can serve as attractive building blocks for novel optoelectronic detectors.

Recent Progress in Solar-Blind Photodetectors Based on Ultrawide Bandgap Semiconductors.

Ultrawide bandgap (UWBG) semiconductors, including Ga2O3, diamond, Al x Ga1-x N/AlN, featuring bandgaps greater than 4.4 eV, hold significant promise for solar-blind ultraviolet photodetection, with applications spanning in environmental monitoring, chemical/biological analysis, industrial processes, and military technologies. Over recent decades, substantial strides in synthesizing high-quality UWBG semiconductors have facilitated the development of diverse high-performance solar-blind photodetectors (SBPDs). This review comprehensively examines recent advancements in UWBG semiconductor-based SBPDs across various device architectures, encompassing photoconductors, metal-semiconductor-metal photodetectors, Schottky photodiodes, p-n (p-i-n) photodiodes, phototransistors, etc., with a systematic introduction and discussion of their operational principles. The current state of device performance for SBPDs employing these UWBG semiconductors is evaluated across different device configurations. Finally, this review outlines key challenges to be addressed, aiming to steer future research endeavors in this critical domain.

Construction of g-C3N4/SnSe2/H-TiO2 Ternary Heterojunction for High-Performance Photodetectors

Two-dimensional layered materials have been widely used in the field of photodetectors because of their unique photoelectric properties. Among them, the multi-heterojunction based on two-dimensional materials with high carrier separation efficiency is expected to be designed as a high-performance photodetector (PD). This work focuses on the fabrication of g-C3N4/SnSe2/H-TiO2 ternary heterojunctions for photodetectors, obtained by depositing SnSe2 and g-C3N4 nanosheets onto TiO2 nanotube arrays using chemical vapor deposition and impregnation methods, respectively. The formation of the g-C3N4/SnSe2/H-TiO2 ternary heterojunction enhances and broadens absorption in the ultraviolet-visible range. Photoelectrochemical measurements have confirmed that the fabricated g-C3N4/SnSe2/H-TiO2 ternary heterojunction photodetector exhibits remarkable light detection capabilities at 370, 450, and 520 nm, meaning broadband photodetection behavior. Notably, under light illumination of 370 nm wavelength, it demonstrates a high responsivity of 2.742 A W−1, an impressive detectivity of 5.84 × 1010 Jones, an external quantum efficiency of 9.21 × 102 %, and excellent stability. This high performance can be attributed to the effective separation and transfer of photogenerated carriers within the ternary heterojunction, significantly enhancing the photoresponse. The construction of the novel broadband-responsive ternary g-C3N4/SnSe2/TiO2 heterojunction holds promise for driving the future development of wideband, high-performance, and highly integrated photodetectors.

Two-Step Laser Ablation for the Synthesis of Au:Pb Core/Shell NPs for a High-Performance Silicon-Based Heterojunction Photodetector

In this work, colloidal gold:lead (Au:Pb) core/shell nanoparticles (NPs) were synthesized in liquid at 532 nm using the laser ablation method. An investigation of the external magnetic field during the laser ablation process affected the properties of the Au:Pb NP core and shell. The magnetic field enhances the core shell’s crystallinity. The optical band gap energy increased from 2.067 to 2.086 eV in the presence of the magnetic field. It also led to an increase in the concentration and a decrease in the size of nanoparticles, which led to increased absorbance. A magnetic field strength of 250 mT resulted in a higher removal efficiency. The external magnetic field significantly reduced NP agglomeration and aggregation. We created and characterized an Au:Pb/porous silicon (PS) heterojunction photodetector. The magnetic field greatly enhanced its properties. The responsively (Rλ) of the photodetector increased from 0.093 to 0.551 A/W at λ = 650 nm by increasing the magnetic field. On the other hand, the final Au:Pb/PS material had the best photocurrent stability, demonstrating that adding Au:Pb NPs can make PS's opto-electrical properties more stable. In the end, the Au:Pb NPs/PS heterojunction photodetector results showed that the photodetector parameters got much better when a magnetic field was present. By altering the preparation conditions, we can produce high-performance core/shell photovoltaic devices.