Photodetection Properties Research Articles

Multispectral photodetection using low-cost sputtered NiO/Ag/ITO heterostructure: From design concept to elaboration

High-performance multispectral photodetectors (PDs) are highly attractive for the emerging optoelectronic applications. In this work, a new broadband PD based on p-NiO/Ag/n-ITO heterostructure was fabricated by RF magnetron sputtering technique at room temperature. The tri-layered structure offering multispectral detection property was first identified using theoretical calculations based on combined FDTD and Particle Swarm Optimization (PSO) techniques. The crystal structure of the elaborated sensor was analyzed using X-ray diffraction (XRD) method. The device optical properties were investigated by UV–Vis–NIR spectroscopy. The NiO/Ag/ITO heterostructured PD shows a high average absorbance of 63% over a wide spectrum range of [200 nm–1100nm]. Compared with NiO and ITO thin-films, the performances of the heterostructured device are considerably enhanced. It was found that the prepared PD with NiO/Ag/ITO heterostructure merges the benefits of multispectral photodetection with reduced optical losses and efficient transfer of photo-induced carrier. The device demonstrated a high ION/IOFF ratio of 78 dB and an enhanced responsivity under UV, visible and NIR lights (171 mA/W at 365 nm, 67 mA/W at 550 nm and 93 mA/W at 850 nm). The broadband photodetection property enabled by the optimized NiO/Ag/ITO heterostructure opens a new route for the elaboration of low-cost devices that can offer multiple sensing purposes, which are highly suitable for optoelectronic applications.

Modified interfaces of twisted root-like 2D configured ZnO hierarchical nanostructures through surface lattice coating of NiO/graphene and their enhanced UV photodetection properties

The formation of edges in 2D configured nanomaterials are special sites which possess different arrangements of atoms and properties compared to that of plain nanomaterials. Herein, a novel strategy is used to synthesize the self-assembled 2D configured edges with twisted building blocks of glucose reduced graphene oxide (grGO)-incorporated NiO-coated ZnO NRs via soft chemical route. It is envisioned that the present hierarchical nanostructures will stimulate the performances of UV photodetection due to these combinations of materials. The as-prepared samples such as ZnO nanorods (NRs), NiO-ZnO NRs, grGO-ZnO NRs and grGO-incorporated NiO-ZnO NRs are designed using Ag interdigitated electrodes. Remarkably, the as-fabricated grGO-incorporated NiO-ZnO NRs shows enhanced photodetection properties when compared to those of bare ZnO NRs, NiO-ZnO NRs and grGO-ZnO. Especially, the grGO-incorporated NiO-ZnO NRs photodetector exhibits the highest UV on/off ratio of 3 × 104 which is ~60 times better than that of bare ZnO NRs photodetector. The results reveal that the development of p-n junction along grGO coating at the surface of NiO-ZnO enhances the relaxation dynamics of ZnO NRs by reducing the photocarriers contact with O2 species due to surface passivation. The present grGO-NiO-ZnO photodetectors might opening up a new opportunities for future optoelectronic devices.

Methylammonium Chloride reduces the bandgap width and trap densities for efficient perovskite photodetectors

Doping dopants are one of the most effective methods which can improve crystallinity, reduce traps, adjust bandgap width of perovskite films and obtain efficient perovskite photodetectors. Chlorine-based dopants have been reported in many literatures, yet their role still remains a mystery. In our study, a typical solution-processed organic–inorganic hybrid perovskite material CH3NH3PbI3 (MAPbI3) was synthesized as the absorption layer for photodetectors and methylammonium chloride (MACl) was selected as dopant. By tuning the incorporation ratios of MACl in the MAPbI3 precursor solutions, bandgap width and trap densities of the MAPbI3 films can be effectively reduced. The crystallinity and morphology of perovskite films were obviously improved, and the photoelectric properties of photodetectors were further enhanced. Ultimately, the optimal device was obtained when the incorporation ratio of MACl reached 1.0 wt%. External quantum efficiency (EQE) of the optimal device exhibited up to 81%, nearly 30% higher than EQE of the device without incorporation. A lower dark current density (Jd) of 8.4 × 10–8 A cm−2 at − 0.1 V bias was obtained because of low trap densities, moreover, due to the suppressed Jd, the optimal device operating at room temperature showed a specific detectivity (D*) of 2.71 × 1012 Jones and a linear dynamic range (LDR) of 104 dB, higher than the D* of 7.03 × 1011 Jones and the LDR of 91 dB of the device without incorporation, respectively.

Multifunctional Flexible Polyimides for Electroactive Devices with Electrochromic, Electrofluorochromic, and Photodetection Properties

In this study, we report three electroactive carbazolyl polyimides (PIs) containing spiropyran, pyrene, and fluorescein fluorescent groups. The PIs exhibit red, blue, and green fluorescence emissio...

High-performance black silicon photodetectors operating over a wide temperature range

Abstract The temperature-dependent photodetection properties of sulfur-hyperdoped silicon fabricated with a femtosecond laser were studied from 10 to 300 K. The fabricated photodetector exhibits high peak photo-responsivity exceeding 10 A/W and extremely high specific detectivity greater than 2×1012 Jones throughout the temperature cycle, as well as wide-band detection sensitivity from 400 to 1200 nm. Carrier behaviors studied from Hall measurements reveal that the ultrafast and ultra-strong interactions between femtosecond laser pulses and silicon induces hyperdoped carriers in a wide distribution of sub-bandgap levels, which guarantees high carrier activities from 10 to 300 K. The wide useful temperature range renders the sulfur-hyperdoped silicon photodetector promising applications in multifunctional optoelectronic devices.

A bioinspired Au-Cu1.97S/Cu2S film with efficient low-angle-dependent and thermal-assisted photodetection properties

SummaryInspired by the geological processes, this study develops an innovative low-concentration-ratio H2 reduction method to reduce the stoichiometric Au-CuS nanoparticles to produce completely reduced stoichiometric Cu2S with “invisible” Au achieved for solid solution Au enhancement. A stable Au-Cu1.97S/Cu2S micro/nano-composite is then formed by spontaneous oxidation. From this composite, in combination with biomimetic technology, an omnidirectional photoabsorption and thermoregulated film (Au-Cu1.97S/Cu2S-C-T_FW) is designed and fabricated as a photothermal-assisted and temperature-autoregulated photodetector for broadband and low-angle-dependent photodetection that presents good performance with high responsivity (26.37 mA/W), detectivity (1.25×108 Jones), and good stability at low bias (0.5 V). Solid solution Au exhibits significantly enhanced photodetection (1,000 times). This study offers a new concept for improving the stability and photoelectric properties of copper chalcogenides. Moreover, it opens up a new avenue toward enhancing the performance of optoelectronic and photovoltaic devices using solid solution metal atoms and thermal-assisted, anti-overheating temperature autoregulation.

Pulse-reactor core monitoring with an innovative optical neutron detector

To minimise uncertainty and strengthen estimation of energy deposited during power transients, we set up an online passive neutron flux measurement of a pulse reactor.Optical fission chambers, are being developed in the framework of dependable neutron flux instrumentation for Sodium-cooled Fast Reactor (SFR) and Molten-Salt Reactor (MSR) of Generation IV by the French Atomic Energy and Alternative Energies Commission (CEA). Neutron interactions with a fissile layer coating release heavy-ions in the MeV-range, eventually leading to spontaneous photon emission in the ultraviolet to infrared range of the surrounding noble gas. Prototypes have previously been tested in an ideal pure neutron field. In this paper, linearity of optical signal versus reactor power is assessed during startups and high power transients up to 21.6 GW. Excellent linearity results are obtained over 5 reactor power decades and detection remain possible over 7 decades. Detection range is only restrained by photodetector properties. Such detector may be routinely employed for high-dynamic transients monitoring by the core caisson of pulse reactors.

High-responsivity solar-blind photodetector based on MOCVD-grown Si-doped β-Ga2O3 thin film* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61774019 and 51572033), the Fund of State Key Laboratory of Information Photonics and Optical Communications (BUPT), and the Fundamental Research Funds for the Central Universities, China.

Si-doped β-Ga2O3 films are fabricated through metal-organic chemical vapor deposition (MOCVD). Solar-blind ultraviolet (UV) photodetector (PD) based on the films is fabricated by standard photolithography, and the photodetection properties are investigated. The results show that the photocurrent increases to 11.2 mA under 200 μW⋅cm−2 254 nm illumination and ± 20 V bias, leading to photo-responsivity as high as 788 A⋅W−1. The Si-doped β-Ga2O3-based PD is promised to perform solar-blind photodetection with high performance.

The Effect of Sn Dopant on the Electrical and Optical Properties of ZnO Thin Films

We study the electrical and optical properties of Sn-doped ZnO (SZO) films grown by DC-unbalanced magnetron sputtering. To study the electrical properties of the films, we perform current-voltage (I-V) measurement by using metal-semiconductor-metal configuration with Ag as a metal contact. The measurement is performed in the dark and under UV exposure condition to study the photodetection properties of the films. From the I-V curve, it shows that the sensitivity of SZO is dramatically enhanced compared to the undoped film. This enhancement is due to the role of Sn dopant, which gives more electrons to the system. Furthermore, UV-Visible spectra reveal that the band gap increase by introducing the Sn dopant. Photoluminescence spectra show SZO film exhibits a higher green emission intensity compared to ZnO film, which is related to the presence of oxygen vacancy. Our result is important to improve the functionality of ZnO for optoelectronic devices applications.

Enhancing the properties of CdO thin films by co-doping with Mn and Fe for photodetector applications

In this communication, we report on how the co-doping of two transition metal ions (Fe and Mn) effectively improves the structural, morphological, optical, electrical and photodetection properties of CdO thin films than individual doping. For this, pure-CdO, Fe-doped, Mn-doped and (Fe-Mn) co-doped CdO thin films are deposited by spray pyrolysis technique. X-ray diffraction (XRD) patterns reveal that these films possess cubic structure and belong to the Fm-3 m space group. The Field Emission Scanning Electron micrographs hold a qualitative agreement with the crystalline sizes obtained from the XRD analysis. Energy Dispersive X-Ray Analysis approved the existence of constituent elements in the prepared films. The photoluminescence spectra identified the quality of crystal structure and the presence of defects in the prepared films. Analyzing the absorption spectra unveiled the direct bandgap values in the range 2.32 eV (for pure-CdO) - 1.96 eV (for CdO:Fe(1%):Mn(1%)). The Hall Effect measurements established n-type behavior with the values of resistivity (ρ), carrier concentration (n) and carrier mobility values in the range 5.8–7.1 mΩcm, 6.7−2.4 × 1019 cm−3 and 16−37 cm2/Vs, respectively. Three different transport mechanisms such as ohmic, recombination-tunneling and space-charge limited current are found to play roles in the three distinct ranges of the I–V data measured for the films under study. The ideality factor values are obtained from the region where the recombination-tunneling mechanism is prevalent. The photoelectric parameters such as photo-responsivity, and external quantum efficiency are obtained. The values of these quantities pertaining to pure-CdO, CdO:Mn, CdO:Fe and CdO:Fe:Mn films vary in the range 128.4–561.3 mA/W, and 30–131.1 %, respectively. From the current study, it was found that photoresponsivity and external quantum efficiency are enhanced by a factor of four in codoped CdO films than the undoped CdO film and can find potential photodetector applications.

Compact integration of GaN-based photonic chip with microfluidics system.

This Letter reports a demonstration of integrating a tiny GaN-based photonic chip with a PDMS microfluidics system. The photonic chip containing InGaN/GaN quantum wells is responsible for light emission and photodetection and fabricated through standard microfabrication techniques. The PDMS-enclosed chip is formed adjacent to the fluidic channel and operates in reflection mode, enabling the optical signals coupled into and out of the fluidic channel without the aid of external optics. The luminescence and photo-detecting properties are thoroughly characterized, confirming that the chip is capable of tracking the continuously flowing microdroplets with the changes of absorbance, length, and flow rate. The novel, to the best of our knowledge, photonic integration presented in this Letter is a significant step forward in the development of compact, miniature, and self-contained on-chip sensing systems, which are of great value in portable lab-on-a-chip applications.

Structural, morphological, optical and enhanced photodetection activities of CdO films: An effect of Mn doping

In this work, undoped and Mn of various concentration (1, 3 and 5 %) doped CdO films prepared by spray pyrolysis procedure using perfume atomizer is reported. XRD analysis of the samples approves polycrystalline nature with cubic system. Change in crystallite size, lattice constant, and cell volume are observed due to the imperfection of crystal lattice. Tightly packed uniformed spherical shape particles are visualised from the morphology anaysis. In PL studies, the emission peaks are observed at 360, 490, 520, and 590 nm. From the UV–vis, the absorbance is increased with doping concentration, which may be due to electronic transition from V to C-band. The bandgap values are decreased with increasing doping concentration (2.51, 2.47 and 2.21 eV) and furher increased for higher doping concentration (2.37 eV). The high resistivity obtained for 3% Mn doped film may be the vital to decrease the dark current and increase the photodetector properties. I–V characteristics of the devices showed increased photosensitivity, responsivity, and quantum efficiency for 3 % of Mn doped film due to high crystallinity, low bandgap, and maximum energy transfer of Mn ions.

Development of low bandgap polymers for red and near-infrared fullerene-free organic photodetectors

Two low bandgap donor polymers, PDTPTT and PCPDTTT, were synthesized and their photodetecting properties were investigated under a 680 nm red LED.

The Basic Category and Application of Graphene-based Hybrid Photodetector

A photodetector is an optoelectronic device that can be divided into inorganic photodetector, which consists of traditional semiconductors, and organic photodetector, the recent direction of researching that made of organic semiconductors with the help of organic dye molecular or other organic compounds. The core of the improvement of photodetector is graphene, a single layer of the two-dimensional (2D) carbon crystalline structure, which provides the property with wide spectral bandwidth and considerably high response speed. This review focuses on the basic knowledge about graphene-based hybrid photodetector, because the hybrid photodetectors have the advantages of breaking the limitation of light absorption and shortening the recombination time of electrons and holes to increase photoresponsivity. Photodetectors can also behave differently when lights are in the infrared, ultraviolet, and terahertz region, so that the selection of materials based on graphene to detect the specific wavelengths of light becomes a challenge. In order to explain the complicated advanced technology briefly, this review can be regarded as two main parts. The first one is the basic properties of inorganic and organic photodetectors with the addition of perovskite, a new material that has been extensively studied recently, and the second part is about how photodetectors can be applied in a different wavelength of lights.

A high-performance short-wave infrared phototransistor based on a 2D tellurium/MoS2 van der Waals heterojunction

A gate-tunable Te/MoS2 vdW heterostructure is fabricated, exhibiting favourable photodetection properties with a response spectrum covering the whole SWIR band.

Dion–Jacobson halide perovskites for photovoltaic and photodetection applications

This review focuses on recent progress involving the photovoltaic and photodetection properties of Dion–Jacobson perovskites and the enhanced stability of Dion–Jacobson perovskite solar cells.

INFRARED DETECTING BEHAVIOURS OF Cu2NiSnS4 PHOTODIODES

A photodetector in Al/p-Si/Cu2NiSnS4/Al form was produced using sol-gel method. Scanning electron microscopy (SEM) was used in the structural assessment of the photodetectors. Microscopic investigations showed that Cu2NiSnS4 structures were formed in nanostructure in granular form. Current–time and current-voltage investigations confirmed that Al/p-Si/Cu2NiSnS4/Al photodiodes have infrared sensing properties. Photodetection properties such as linear dynamic rate, ideality factor, photosensitivity, and photoresponse characteristics were assessed. Results also validate the infrared sensing properties of the diodes. The barrier height of the Al/p-Si/Cu2CoSnS4/Al diodes was calculated as 0.466 eV. Ideality factor of the diodes was found to be 5.16. Results indicate that our Al/p-Si/Cu2CoSnS4/Al diodes are suitable for infrared tracking device applications.

Optical and Photodetection Properties of ZnO Nanoparticles Recovered from Zn Dross

In this study, we report the synthesis of ZnO nanoparticles from Zn dross via hydrometallurgical method by using acetic acid as a leaching agent. D205 dye molecules were then adsorbed onto Zn dross originated ZnO nanoparticle film. The optical absorption confirms the photosensitization of the synthesized ZnO nanoparticles with dye. The photoluminescence spectra reveal the excitonic- and defect-related emission of ZnO nanoparticles. Compared to ZnO nanoparticles only, the longer emission lifetime of ZnO nanoparticles with adsorbed dye indicates the transfer of photoexcited electrons from dye to the ZnO nanoparticles. Furthermore, photodetection characterization of ZnO film show the enhanced current density with the presence of dye under simulated solar illumination, while that measured at dark is similar in both films with and without dye. This result confirms the potentiality of Zn dross to be recycled into valuable ZnO nanoparticles particularly for the applications in the visible light region, especially for sensing.

Self-powered photodetector with improved and broadband multispectral photoresponsivity based on ZnO-ZnS composite

Cost-effective multispectral photodetectors (PDs) exhibiting a high UV-Visible-NIR photoresponse offer an avenue for developing environmental monitoring devices, imaging sensors, object discrimination, and optical links. However, PDs based on a single semiconductor as light-sensitive layer are unable to provide broadband photodetection properties. In this work, a new PD device based on ZnO-ZnS Microstructured Composite (MC) which achieves a high UV-Visible-NIR photoresponse is demonstrated. The ZnO-ZnS MC is elaborated by combining vacuum thermal evaporation technique and a suitable annealing process. Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and UV-Vis-NIR spectroscopy were used to elucidate the morphological, structural and optical properties of the prepared sample. It was demonstrated that the ZnO-ZnS MC can be useful to enhance the visible absorbance efficiency by promoting efficient light-scattering effects. It is revealed that the prepared UV-Vis-NIR PD offers a low dark current of 5 nA, a high ION/IOFF ratio of 78 dB and an enhanced responsivity in UV, visible and NIR ranges. The proposed multispectral PD demonstrates a high ION/IOFF current ratio under self-powered working regime. Therefore, the proposed ZnO-ZnS MC is believed to provide new insights in developing efficient, self-powered and low-cost multispectral PDs for high-performance optoelectronic systems.

Impact of seed layer annealing on the optoelectronic properties of double-step CBD grown n-ZnO nanowires/p-Si heterojunctions

In the current work, n-ZnO nanowires are grown by employing double-step chemical bath deposition (CBD) technique on p-Si substrate for the fabrication of n-ZnO nanowires/p-Si heterojunction diodes. The as-deposited ZnO seed layer is furnace annealed at 400 °C and 600 °C for 30 min in argon ambient for studying comparative changes of their optoelectronic properties. The systematic change of surface morphology, chemical compositions, crystallite structure, oxidation states, defect levels and photodetecting properties due to annealing of the seed layer has been investigated. Annealing the seed layer at 400 °C exhibits a nanosphere-like structure and provides superior nucleation sites for vertical growth of the nanowires in comparison to the as-deposited and 600 °C -annealed samples. The electrical, electro-optical and physical characterization results suggest the nanowires grown on 400 °C -annealed ZnO seeds to provide superior performance.