Photodetector Applications Research Articles

Synthesis and characterization of WO3/BiS2/rGO composites for enhanced optoelectronic performance in photodetector applications

This research investigates into the fabrication and application of WO3/BiS2/rGO composites in enhancing the optoelectronic performance of photodetectors. The composite synthesis encompasses the acid oxidation of graphene oxide (GO), the hydrothermal generation of WO3 nanorods, and the subsequent amalgamation with bismuth sulfide (BiS2) and reduced graphene oxide (rGO). This study exploits the distinctive photoresponse characteristics of WO3, the narrow bandgap properties of BiS2, and the conductive attributes of rGO, meticulously examining their combined effect on improving the device's performance metrics. Extensive spectroscopic and microscopic investigations confirm the successful synthesis of the composites, uncovering detailed structural insights. The evaluation of key parameters such as responsivity, detectivity, photoresponsivity (3.74 A/W), and specific detectivity (1.38 × 1013 Jones) underscores the composites' superior performance over individual constituents and current composite materials. By strategically integrating WO3, BiS2, and rGO, this research addresses vital challenges in photodetection technology, significantly contributing to the development of advanced composite materials for optoelectronic applications. The comprehensive optimization and characterization of WO3/BiS2/rGO composites mark a pivotal step towards their incorporation in next-generation photodetectors, heralding promising advancements in sensing and imaging technologies.

Phase Transition and Bandgap Engineering of MgSnO Thin Films for Solar-Blind Ultraviolet Photodetector Applications

Phase Transition and Bandgap Engineering of MgSnO Thin Films for Solar-Blind Ultraviolet Photodetector Applications

Bifunctional g-GaN/Si9C15 S-scheme heterojunction for efficient photocatalytic hydrogen evolution and photodetector

S-scheme heterojunctions are commonly applied in optoelectronic devices and photocatalytic materials to achieve effective charge separation and enhance photocatalytic activity. In this study, the electronic, optical, and electrical behaviors as well as the photocatalytic water splitting performance of the g-GaN/Si9C15 S-scheme heterojunction have been researched using first-principles. The results suggest that the g-GaN/Si9C15 heterojunction is energetically, thermally, and dynamically stable. The g-GaN/Si9C15 heterojunction belongs to the S-scheme photocatalyst with the g-GaN as the oxidant and the Si9C15 as the reductant, and its band edge positions cross the standard water oxidation and reduction potentials. The g-GaN/Si9C15 heterojunction has a power conversion efficiency of 11.03 % and a large carrier mobility of 20.98 × 103 cm2 V−1 s−1. The small overpotential of 0.076 V is favorable for the occurrence of the hydrogen evolution reaction, and the oxygen evolution reaction of the g-GaN/Si9C15 heterojunction can spontaneously proceed when U = 1.23 V. The g-GaN/Si9C15 heterojunction exhibits a large solar-to-hydrogen efficiency of 25.58 %. Moreover, the g-GaN/Si9C15 heterojunction has a high photocurrent and a large extinction ratio. In conclusion, the g-GaN/Si9C15 heterojunction holds potential applications in photocatalytic water splitting and photodetector.

Vibrational mode of low-dimensional ionic liquid bismuth hybrid perovskite probed by FTIR and Raman Spectroscopy

Bismuth-based hybrid organic-inorganic perovskites (Bi-HOIPs) are developed as lead-free halide perovskites due to their low toxicity and good stability. In this study, the incorporation of ionic liquid (IL) cations in the Bi-HOIPs structure, namely 1-butyl-1-methylpyrrolidinium (BMP) and 1-(3-aminopropyl) imidazole (API), are investigated. Bi-based HOIPs are kept in ambient conditions (20–25 °C) to compare the structural differences in FTIR and Raman spectra between pristine and aged samples. The FTIR and Raman spectra of all aged samples are slightly shifted after being retrieved at the ambient conditions for four months (∼below 45 cm−1). Our work paves the way in developing Bi-based HOIPs for solar cells and photodetectors applications.

WITHDRAWN: Investigating the ERG a-wave and Retinal Diseases with Rod Equivalent Circuit Model Based on the APD

Most empirically supported mathematical models of rod cells lack theoretical support from actual physical devices. Therefore, this paper proposes an equivalent circuit model for the rod is proposed based on the photoconductive properties of the avalanche photodetector (APD) and combined with the electrical properties of the rod. The model employs the photodetector to simulate the source of the photocurrent in outer segments of rod cells and takes into account the electrical properties of the inner and outer segments, the nucleus, and the synaptic terminals. It successfully simulates the trans-retinal voltage generated by the intracellular and extracellular flow of photocurrent in the outer segment of dark-adapted rods. Moreover, the typical waveform characteristics of two retinal diseases, the enhanced short wavelength sensitivity (SWS) cone syndrome and retinitis pigmentosa (RP), are investigated on the basis of electroretinogram (ERG) a-wave. This will further elucidate the function of the visual system and the ERG a-wave characteristics of the related diseases. Comparison with published experimental results validates the reliability of the model presented. Our study provides new ideas and strategies for the diagnosis of retinal diseases and provides some theoretical support for the application of photodetectors in the fabrication of artificial retinal devices.

Solar-Blind Photodetector Arrays Fabricated by Weaving Strategy.

The quest for solar-blind photodetectors (SBPDs) with exceptional optoelectronic properties for imaging applications has prompted the investigation of SBPD arrays. Ga2O3, characterized by its ultrawide bandgap and low growth cost, has emerged as a promising material for solar-blind detection. In this study, SBPD arrays were fabricated by weaving Sn-doped β-Ga2O3 microbelts (MBs). These MBs, which have a conductive core surrounded by a high-resistivity depletion surface layer resulting from the segregation of Sn and oxygen, are woven into a grid structure. Each intersection of the MBs functions as a photodetector pixel, with the intersecting MBs serving as the output electrodes of the pixel. This design simplifies the readout circuit for the photodetector array. The solar-blind photodetector array demonstrates superior solar-blind detection performance, including a dark current of 0.5 pA, a response time of 38.8 μs, a light/dark current ratio of 108, and a responsivity of 300 A/W. This research may provide a feasible strategy for the fabrication of photodetector arrays, thus pushing forward the application of photodetectors in imaging.

Fast response fabricated MoS2-photodiode based thin film

In this study, we present the fabrication and characterization of a thin film based on 1 T-MoS2 pn photodiode for the purpose of quick response photodetection application. The photodiode was fabricated using RF-sputtering process. The scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) techniques were employed to investigate the surface topology and structural characteristics of the nanostructured MoS2 thin film. The electrical properties of the photodiode that was produced were examined by conducting measurements of its current–voltage (I-V) characteristics across a range of bias voltages spanning from − 2 to + 2 V. The external quantum efficiency (EQE) of the pn photodiode that was produced was determined to be as high as 9.8%. Additionally, the internal quantum efficiency (IQE) was found to be as high as 10.5%. Furthermore, a time response of 1.748 ms was observed. The findings of this study illustrate the capability of MoS2 photodiodes in facilitating rapid response photodetection applications.

Highly stable mixed-phase Cs-Cu-I films with tunable optoelectronic properties for UVB photodetector applications.

Ultraviolet (UV) photodetector plays an important role in military, civilian and people's daily life, and is an indispensable part of spectral detection. However, photodetectors target at the UVB region (280-320 nm) are rarely reported, and the devices detected by medium-wave UV light generally have problems such as low detection rate, low sensitivity, and poor stability, which are difficult to meet the market application needs. Herein, Cs-Cu-I films with mixed-phase have been prepared by vacuum thermal evaporation. By adjusting the proportion of evaporation sources (CsI and CuI), the optical bandgaps of mixed-phase Cs-Cu-I films can be tuned between 3.7 eV and 4.1 eV. This absorption cut-off edge is exactly at both ends of the UVB band, which indicating its potential application in the field of UVB detection. Finally, the photodetectors based on Cs-Cu-I/n-Si heterojunction are fabricated. The photodetector shows good spectral selectivity for UVB band, and has a photoresponsivity of 22 mA/W, a specific detectivity of 1.83*1011 Jones, an EQE over 8.7% and an on/off ratio above 20.

Impact of Mo doping on photo-sensing properties of ZnO thin films for advanced photodetection applications

This work explored the impact of Mo-doping on the structural, optical, photophysical, and electrical characteristics of ZnO thin films and their potential application to the UV light detection properties was investigated. The hexagonal structure of the films without any impurities or extra phases was confirmed by X-ray diffraction and FT-Raman spectroscopy. The crystallite size reduced from 36 nm to 25 nm with the addition of 3 wt% of Mo in ZnO. The EDX/SEM e-mapping verified the elemental composition and uniform Mo doping throughout the films. The FESEM images revealed spherical nanoparticles with smaller grains size for higher Mo-doping levels. The absorption spectra were recorded from UV to NIR range, and the bandgap was observed to increase from 3.25 eV for pure ZnO to 3.42 for 3% Mo-doped ZnO sample. The Mo-doped ZnO film showed PL quenching, which indicates charge transfer and suppression of defect sates in the ZnO films via Mo-doping. The time-resolved fluorescence spectra (TRFS) of these films revealed that the carrier lifetime increased from 80 ps for pure ZnO to 144 ps for 3% Mo-doped ZnO thin film. The electrical parameters including resistivity, carrier mobility, concentrations, and sheet resistance of fabricated films were evaluated by Hall-effect measurement. The resistivity and mobility were observed to decrease from 9.33×104 Ω.cm, 55.1 cm2/V.s to 2.03×103 Ω.cm 15.4 cm2/V.s for 3% Mo-doped ZnO thin film, while carrier density increased. The photodetection study demonstrated that the responsivity, detectivity, external quantum efficiency and response time of devices were significantly enhanced with Mo idoping.

High-responsivity photodetectors made of indium selenide with visible to near-infrared photodetection

This study demonstrates indium selenide (InSe) photodetectors (PDs) with a broadband photodetection range from the visible to the near-infrared (NIR) region (400–1000 nm). The InSe flakes exfoliated from bulk material are transferred to a sapphire substrate, followed by the deposition of Ni/Au bi-layer metal contact to fabricate the metal-semiconductor–metal (M-S-M) PDs. In addition to an absorption edge at around 1000 nm, a strong absorption edge at around 516 nm is observed from the typical spectral response taken from the fabricated InSe M-S-M PDs. Under a bias voltage of -1 V, the typical responsivity at 400 nm is as high as 1130 A W-1, corresponding to a photoconductive gain of approximately 3500. Thus, InSe has potential application in broadband photodetection from the NIR to the visible region.

Construction of branched SnS2/Te heterostructure film for self-powered high-performance photodetector application

Effective design and construction of heterostructure can conduce to charges transportation/separation and simultaneously improve light absorption ability of photoelectrochemical (PEC) photoelectrode. In this work, the p-type Te nanorods were directly grown on the surface of ultra-thin SnS2 nanoflakes via a facile and low-cost electrochemical deposition (ED) method. The PEC performance of mixed-dimensional branched SnS2/Te nanoflakes/nanorods (NFRs) heterostructure composites film was optimized by varying the ED time. Under simulated light illumination of 40 mW/cm2, the optimal photocurrent density of the SnS2/Te NFRs photoanode significantly reached up to 0.95 mA/cm2, approximately 5.2 times and 3.5 times larger than those of bare SnS2 and Te film, respectively. The improved performance was attributed to appropriate energy band matching and intensive light absorption property. In particular, it presented good stability and high light on/off ratio of about 4.1 ×106 at the 0 bias voltages, suggesting an excellent self-powered characteristic of the device. Furthermore, the SnS2/Te NFRs photodetector exhibited photoresponsivity of 127 mA/W at 0.8 V bias and photodetectivity of 1.33 ×1011 Jones, respectively. This study presents a rational strategy to improve the photodetection performance of SnS2-based PEC-type photodetector and opens a new avenue for designing high-efficiency photoelectronics device.

Mid-infrared bimodal wide metamaterial absorber based on double-layer silicon nitride structure

Infrared band occupies a very important position in the electromagnetic wave band. Traditional infrared devices use the inherent properties of natural materials to achieve the regulation of electromagnetic waves, but the limited ability of such devices to regulate electromagnetic waves can't well meet our needs. In this paper, we reported a metamaterial absorber of Cr-Si3N4-Cr-Si3N4-Ti based on double-layer metal-insulator-metal (MIM). It is investigated with the optimal structural parameters of 490 nm, 330 nm, 30 nm, 720 nm, 120 nm, in descending order, at which the absorptive properties are studied. When the light wave is incident vertically, it can be obtained from the experimental simulation that this absorber has polarisation insensitivity. Because of the coupling effect of the surface plasmon resonance and the high-loss material, the bandwidth of absorption greater than 90% can reach 9190 nm, and the average absorption in the target long-wave infrared band (9.506∼18.145 μm) is 94.8%. By selecting different geometrical parameters of the structure, the absorption spectrum can be adjusted independently. In addition, the absorber has good incident angle insensitivity in TE and TM modes. Also, the absorber we proposed has a plain structure, is convenient for manufacturing, the material is easier to obtain, which ensures a good absorption bandwidth and average absorptivity, and the study of this metamaterial absorber has important applications in solar cells, satellite radiothermographs, photodetectors, and spectral imaging.

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications.

GeSn alloys have recently emerged as complementary metal-oxide-semiconductor (CMOS)-compatible materials for optoelectronic applications. Although various photonic devices based on GeSn thin films have been developed, low-dimensional GeSn quantum structures with improved efficiencies hold great promise for optoelectronic applications. This study theoretically analyses Ge-capped GeSn pyramid quantum dots (QDs) on Ge substrates to explore their potential for such applications. Theoretical models are presented to calculate the effects of the Sn content and the sizes of the GeSn QDs on the strain distributions caused by lattice mismatch, the band structures, transition energies, wavefunctions of confined electrons and holes, and transition probabilities. The bandgap energies of the GeSn QDs decrease with the increasing Sn content, leading to higher band offsets and improved carrier confinement, in addition to electron-hole wavefunction overlap. The GeSn QDs on the Ge substrate provide crucial type-I alignment, but with a limited band offset, thereby decreasing carrier confinement. However, the GeSn QDs on the Ge substrate show a direct bandgap at higher Sn compositions and exhibit a ground-state transition energy of ~0.8 eV, rendering this system suitable for applications in the telecommunication window (1550 nm). These results provide important insights into the practical feasibility of GeSn QD systems for optoelectronic applications.

Amorphous Gallium Oxide Nanosheets with Broad Absorption and Spin Polarization for Si‐Based UV‒Vis‒NIR Photodetectors

AbstractAchieving broad light absorption and high carrier separation efficiency is crucial for wide‐bandgap semiconductors to enable broadband photodetection applications. Here, amorphous gallium oxide nanosheets feature with broad absorption and spin polarization Wis synthesized, and assembled with graphene and p‐Si, realizing UV‒vis‒NIR photodetection. Extended X‐ray absorption fine structure reveals that a‐GaOx NSs possess lower tetrahedral Ga occupation (10%) compared to crystalline β‐Ga2O3 (50%). UV‒vis‒NIR diffuse reflectance spectra and magnetic hysteresis loops demonstrate broad absorption and weak ferromagnetism of a‐GaOx NSs, respectively. Density functional theory calculation further reveals sub‐gap states and spin polarization in a‐GaOx NSs. Moreover, combined with Mott–Schottky curves, photoluminescence and time‐resolved photoluminescence spectra inferred the effective suppression of carrier recombination via spin polarization of a‐GaOx NSs. The graphene/a‐GaOx NSs/p‐Si photodetector incorporates a back‐to‐back rectifying junction, acquiring a dark current as low as 63 pA. All photogenerated carriers are in the depletion region of the photodetector favouring efficient charge separation. This photodetector exhibits a response time of τrise<60 ms and τfall<120 ms, and high specific detectivity 1013 Jones over 254–1064 nm light.

Sustainable Production of Ultrathin Ge Freestanding Membranes

Germanium (Ge) is a critical material for applications in space solar cells, integrated photonics, infrared imaging, sensing, and photodetectors. However, the corresponding cost and limited availability hinder its potential for widespread applications. However, using Ge freestanding membranes (FSMs) allows for a significant reduction in the material consumption during device fabrication while offering additional advantages such as lightweight and flexible form factor for novel applications. In this work, we present the Ge FSM production process involving sequential porous Ge (PGe) structure formation, Ge membrane epitaxial growth, detachment, substrate cleaning, and subsequent reuse. This process enables the fabrication of multiple high-quality monocrystalline Ge FSMs from the same substrate through efficient substrate reuse at a 100 mm wafer scale by a simple and low-cost chemical cleaning process. A uniform, high-quality PGe layer is produced on the entire recovered substrate. By circumventing the use of conventional high-cost chemical–mechanical polishing or even substantial chemical wet-etching, and by using an optimized PGe structure with reduced thickness, the developed process allows for both cost and an environmental impact reduction in Ge FSMs production, lowering the amount of Ge used per membrane fabrication. Moreover, this process employs large-scale compatible techniques paving the way for the sustainable production of group IV FSMs for next-generation flexible optoelectronics.

Mist Chemical Vapor Deposition of Bi13S18I2 for Photoelectrochemical-type Photodetection.

Bismuth-based ternary compounds have attracted much attention owing to their various merits, such as low toxicity and tunable electrical and optical properties. However, these compounds are yet to be understood due to the lack of suitable targets limited by immature synthesis techniques. In this work, we aimed at the synthesis, properties investigation, and photodetection application of Bi13S18I2. Mist chemical vapor deposition was adopted for the deposition of the Bi13S18I2 thin film for the first time. The deposition mechanism was discussed from the perspective of crystal phase and surface morphology. Based on the Bi13S18I2 thin film synthesized at optimal temperature, we constructed a photoelectrochemical-type photodetector. The photodetection performance was evaluated from the points of electrolyte composition, working temperature, and bias voltage. This study would pave the way for the controllable synthesis and applications of bismuth-based ternary compounds.

Ag nanoparticle decorated β-Ga2O3 nanowires on Si substrates: advancing photodetector technology

In this study, we present the fabrication of Ag nanoparticle (NP) decorated β-Ga2O3 nanowire (NW) on a Si-substrate, with a focus on their application in photodetection. The resulting Ag NP decorated β-Ga2O3 NW exhibited a polycrystalline morphology characterized by well-aligned rows of vertically oriented structures. The mean size of the crystallites was revealed to be approximately 15.94 nm. The fabrication of Ag NP decorated β-Ga2O3 NW displayed uniformity, with an average length of approximately ∼180 nm. The UV-Vis absorption spectroscopy analysis yielded an approximate optical bandgap value of 4.74 eV. Notably, the fabricated photodetector exhibited excellent performance characteristics. This was highlighted by the minimal dark current of −3.2 nA at a bias voltage of −1 V, accompanied by an I L/I D ratio exceeding 50. Moreover, the photodetector demonstrated rapid rise and fall times of 0.023 s and 0.021 s, respectively. The remarkable aspect lies in the simultaneous attainment of minimum dark current and swift response times. The Ag NP-decorated β-Ga2O3 NW photodetector exhibited consistent and reproducible behavior, suggesting its potential for realistic use in ultraviolet photodetection.

HBN‐Encapsulated Graphene Coupled to a Plasmonic Metasurface via 1D Electrodes for Photodetection Applications

It is shown here how encapsulated graphene devices can be laterally coupled to plasmonic metasurfaces via 1D edge contacts, preserving the high mobility of encapsulated graphene while enhancing optical coupling. The device is used for photodetection applications where high responsivities in the range of 100 A W−1 for most of the visible spectrum are reported. The device exhibits a photogating effect which is attributed to defect states in the encapsulating hBN layers. The results highlight a new configuration to couple graphene with plasmonic structures and points to a new type of device based on defect states and graphene's excellent transport properties to achieve photodetectors with ultrahigh responsivities.

Numerical investigation on performance improvement of CuO/TiO2 heterojunctions for applications in sunlight-driven photodetectors and photocatalysts

Numerical investigation on performance improvement of CuO/TiO2 heterojunctions for applications in sunlight-driven photodetectors and photocatalysts

A photodetector based on p-GaN/N-MoS2 QDs heterojunction with high responsivity

Molybdenum disulfide (MoS2) is the most thoroughly investigated for photodetection applications with direct bandgap transition in low-dimensional structures, high light–matter interaction, and good carrier mobility. In this work, MoS2 quantum dots was synthesis by liquid exfoliation and characterized using scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fluorescence emission spectra (FES), UV–vis spectroscopy, and Photoluminescence (PL). The average size is ∼ 3.6 nm with strong absorption in the UV region and a band gap of 4.49 eV. Moreover, a novel structure of N- MoS2 QDs \\ p-GaN heterojunction photodetector was deposited by spray coating. The PL of N- MoS2 QDs \\ p-GaN emission spectra expanded from UV to visible light with high responsivity to the visible light of 7.06 mA W−1 and detectivity of 1.24 × 1010 jones.