Sensitive Photodiode Research Articles

Cost-effective self-powered heterostructure π-SnS/Si photodetector with superior sensitivity for near-infrared light

Photodetectors generally require external power supplies to facilitate the separation of charge carriers and the generation of photocurrents. This significantly enlarges the device's dimensions and weight, limiting its applicability in real-time medical therapy monitoring and wireless environmental sensing. To address this limitation, extensive research focuses on developing self-powered photodetectors that operate autonomously without external power sources. The heterojunction structure photodetector, characterized by a sufficient built-in potential, facilitates the separation of photo charge carriers and the generation of photocurrent, leading to self-powered photodetectors. In this study, a novel and straightforward heterostructure photodetector was developed using a tin monosulfide (π-SnS) film and silicon (Si). This device exhibited a barrier height of 0.82 eV, which effectively separates photogenerated carriers and results in a highly sensitive (5.7 × 104) self-powered photodiode for near-infrared light. The SnS film was deposited onto an n-type Si wafer substrate using a simple and cost-effective chemical bath deposition method. The photoresponse characteristics were controlled and tuned by adjusting the operating bias voltage and illumination power density. At a bias voltage of 5 V, the photodiode demonstrated high responsivity (3863 mA/W) and detectivity (7.2 × 1011 Jones). The π-SnS/Si self-powered heterojunction photodetector, with its superior sensitivity, holds promise for advancing the technological implementation of optoelectronic devices.

Advanced photodetector for hybrid PET-MRI systems

Background Currently, a wide variety of silicon photomultipliers (SiPMs) are available, each designed for specific applications in fields such as science, medicine, and industry. Advances in production technology have led to the development of more sensitive and efficient photodiodes, which are critical for applications requiring precision, such as medical imaging. Methods A research group has been working on designing a highly sensitive photodiode to enhance the capabilities of next-generation PET-MRI scanners. This involves integrating micropixel avalanche photodiodes (MAPDs) to improve image resolution. The chosen design features deep-immersion MAPDs with a pixel size of 12 microns and a density of 1000 pixels per square millimeter, allowing for high-detail photon detection. The 4x4 mm2 active area is optimized to balance sensitivity and size for high-resolution medical imaging. To produce these photodiodes, the group has outlined a production plan involving 20-inch silicon wafers grown using multiple techniques to enhance material properties. The Malaysian Institute of Microelectronic Systems (MIMOS), renowned for its expertise in optical microelectronics, was selected as the production center. With MIMOS' state-of-the-art facilities, the project aims to meet stringent medical diagnostics standards. Results The experimental results demonstrated that the MAPD-3NM photodiode achieved an amplification factor 1.8 times greater than the MAPD-3NK under optimal conditions. Its overvoltage range increased by 100%, reaching 4 V, enhancing photon detection and amplification. The MAPD-3NM also showed a significant reduction in dark current, about 3.5 times lower than the MAPD-3NK, improving performance in low-light environments. Additionally, the MAPD-3NM had a capacitance of 200 pF compared to 176 pF for the MAPD-3NK, contributing to its superior performance. These improvements make the MAPD-3NM more efficient and sensitive for scientific and medical applications. Conclusions This project represents a major advancement in photodetector technology for medical diagnostics, aiming to develop more accurate and efficient PET-MRI scanners that enhance patient outcomes with improved imaging capabilities.

Determining absolute VUV fluxes for assessing the relevance of photon-surface interaction in ion sources

A portable device was developed to quantify VUV fluxes flexibly at ion source setups. It consists of a VUV sensitive photodiode and optical filters for wavelength selection and is calibrated against a VUV spectrometer down to 46 nm for a variety of discharge gases, including Ar, N2, O2 and H2. It was applied to the negative hydrogen ion source at BATMAN Upgrade to quantify the VUV radiation emitted by the driver as well as in front of the extraction surface (plasma grid, PG). The combined VUV fluxes impinging on the PG with photon energies larger than 6.6 eV has a comparable magnitude as the ion flux. It could be shown that the recently confirmed influence of the ion source plasma on the surface work function of the PG can at least partly be ascribed to the VUV radiation from the driver and that photo-emitted electrons from the PG should not play a role in the sheath physics.

Highly efficient self-powered CH3NH3Pbl3 perovskite photodiode with double-sided poly(methyl methacrylate) passivation layers

Hybrid organohalide perovskites have recently attracted significant attention due to their outstanding photovoltaic (PV) conversion capabilities in optoelectronic devices. Herein, to develop a highly sensitive and self-powered perovskite-based PV photodiode (PVPD), we implement the selective use of poly(methyl methacrylate) (PMMA) as noise-current-reducing passivation layers on both the front and rear sides of a CH3NH3PbI3 (MAPbI3) perovskite light-absorbing layer. It is found that the PMMA layers effectively suppress carrier recombinations at the interfaces, resulting in fairly high power conversion efficiency of 17.6%. Additionally, the double-sided PMMA-passivated MAPbI3 PVPD shows exceptional specific detectivity values (1.0 × 1014 Jones from the dark current and 1.3 × 1012 Jones from the noise current), significantly outperforming conventional MAPbI3 PVPDs without passivation layers. The device also exhibits a very wide linear dynamic response range of ∼139 dB, with rapid rise and decay response times of 57 and 18 μs, respectively. The double-sided PMMA-passivated MAPbI3 PVPD also is shown to be highly durable in terms of its dynamic responses even after a prolonged storage period of 1500 h. These results suggest that advanced interface engineering using double PMMA passivation layers holds great potential for developing high-performance self-powered perovskite photodetectors for a range of optoelectronic applications.

Embellished photosensitive Schottky barrier diode functionality of Ni(II)/Pb(II)-Salen complex with SCN− spacers: Insights from experimental and theoretical rationalization

This research article explores the synthesizing, structural characterizing, and photosensitive Schottky diode behaviour (PSBD) of one new hetero-nuclear Ni(II)/Pb(II)-Salen complex, [Ni2(L)Pb(μ-1,3-SCN)2(H2O)]2. The complex utilizes various analytical methods for characterization purposes, including single-crystal X-ray diffraction (SCXRD). Crystals have formed in the monoclinic space group P21/n within the compound. The complex asymmetric unit contains a deprotonated ligand (L2−), two Ni(II), one Pb(II), two SCN− ions, and Ni(II) metal coordination by H2O molecule. The crystallographic structure has octahedral and see-saw geometries around the Ni(II) and Pb(II) metal ions. The crystal structure reveals remarkable supramolecular interactions, with significant S⋯H contacts (13 %) evident from the Hirshfeld surface (HS) and 2-D fingerprint plots. The calculated optical band gap (3.14 eV) and UV–Visible measurement support the semiconductor behaviour. In addition, the compound shows electrical conductivity and photosensitivity (dark & light), suggesting potential applications in optoelectronic devices. The complex transports charge through space via a hopping process. The extensive experimental investigations indicate that exposure to visible light increases electrical conductivity compared to dark conditions, popularly known as PSBD behaviour. The complex conductivity function substantiates the DFT-based DOS, PDOS, and OPDOS plot analysis. Therefore, the heteronuclear complex has been successfully used in thin-film active devices despite technological challenges.

Synthesis, characterization, crystal structure, and fabrication of photosensitive Schottky device of a binuclear Cu(ii)-Salen complex: a DFT investigations.

This work explores one centrosymmetric binuclear Cu(ii)-Salen complex synthesis, characterization, photosensitive Schottky barrier diode (PSBD) function, and DFT spectrum. The crystal growth involves H2LSAL and Cu(NO3)2·3H2O in CH3OH + ACN (acetonitrile) solvent medium. Herein, structural characterization employs elemental, IR/Raman, NMR, UV-VIS, DRS, SEM-EDX, PXRD, SCXRD, and XPS analyses. The complex crystal size is 0.2 × 0.2 × 0.2, showing monoclinic space group C2/c. The dimeric unit contains two Cu(ii) centres with distorted square pyramidal (SQP) geometries. The crystal packing consists of weak C-H⋯O interactions. DFT and Hirshfeld surface (HS) further substantiated the packing interactions, providing valuable insights into the underlying mechanisms. The 2-D fingerprint plots showed the presence of N⋯H (3%) and O⋯H (8.2%) contacts in the molecular arrangement. NBO, QTAIM, ELF-LOL, and energy frameworks are utilized to investigate the bonding features of the complex. We extensively studied electrical conductivity and PSBD for H2LSAL and the complex based on band gap (3.09 and 3.07 eV). Like an SBD, the complex has better electrical conductivity, evidencing potentiality in optoelectronic device applications. Optical response enhances conductivity, according to I-V characteristics. Complex Schottky diode has lower barrier height, resistance, and higher conductivity under light. The complex transports charge carriers through space and is rationalized by the 'hopping process' and 'structure-activity-relationship' (SAR). The charge transport mechanism was analysed by estimating complex mobility (μeff), lifetime (τ), and diffusion length (LD). The experimental and theoretical DOS/PDOS plots provide evidence for the Schottky diode function of the complex.

Application of a distinctly bent, trinuclear, end-to-end azide bridged, mixed valence cobalt(iii/ii/iii) complex in the fabrication of photosensitive Schottky barrier diodes.

A mixed-valence trinuclear cobalt(iii)-cobalt(ii)-cobalt(iii) complex, [(μ-1,3-N3)Co3L(N3)3]·MeOH has been synthesized using a tetradentate N2O2 donor 'reduced Schiff base' ligand, H2L {1,3-bis(2-hydroxybenzylamino)2,2-dimethylpropane} and azide as anionic co-ligand. The complex has been characterised by elemental analysis, IR, UV-vis spectroscopy and single-crystal X-ray diffraction studies etc. The cobalt(iii)-cobalt(ii)-cobalt(iii) skeleton in the complex is non-linear and non-centrosymmetric. The redox behavior of the complex was studied by using Cyclic Voltammetry (CV). The complex is found to be a semiconductor material as confirmed by determining the band gap of this complex by experimental as well as theoretical studies. The band gap in the solid state has been determined experimentally. The conductivity of the synthesized complex based device improves considerably in illumination conditions from the non-illuminated conditions. The complex has also been used to fabricate Schottky barrier diodes.

Equal proportion of donor/acceptor active layer for reduced dark current in visible organic photodiode

The present study investigates a visible organic photodiode with low dark current of 0.002 mA/cm2. The active layer is a bulk heterojunction (BHJ) binary blended film composed of Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) as a donor material along with (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) as an acceptor material. The device was fabricated using a facile spin coating technique with the structure of ITO/PEDOT:PSS/PCDTBT:PC71BM/Al. The composition of PCDTBT and PC71BM has significantly improved the absorption of the UV–visible spectrum, especially between 300 and 650 nm. The optimized device of the blended film (1:1 blend ratio) showed a good photoresponsivity of 114 mA/W, with a fast response-recovery time of 733 ms and 597 ms, respectively. It is found that the specific detectivity obtained is 1.79×109 Jones and external quantum efficiency (EQE) is 29.13 %. The results manifested the optimized device can be employed in the fabrication of a cost-effective and highly sensitive visible organic photodiode.

Investigation of Ag/ZnO/p-Si heterostructure for diode and photodiode applications in visible spectrum

Photodiodes have gained great attention for lightning control and optical communication over the last two decades. To obtain faster and more sensitive photodiodes are important for industrial applications. In this study, atomic layer deposition (ALD) technique was used to fabricate ZnO interlayer on p-Si, and thermal evaporation technique was employed to deposit Ag rectifying and Al ohmic contacts on ZnO and back surface of p-Si, respectively. The UV–Vis spectrometer was used to characterize optical behaviors of the ZnO interlayer. I-V measurements were conducted to characterize of Ag/ZnO/p-Si heterostructure for various solar light power intensities of dark, 20, 40, 60, 80 and 100 mW cm−2 and at various wavelengths from 351 nm to 800 nm by 50 nm intervals. According to I-V characteristics, the device exhibited increasing current at reverse biases depending on increasing light power intensity, and this confirmed photodiode behavior. Various diode parameters such as rectifying ratio, threshold voltage, series resistance, barrier height, etc. were determined and discussed in details from forward bias characteristics to investigate diode characteristics of the Ag/ZnO/p-Si heterostructure. The photodetection parameters such as responsivity, specific detectivity and external quantum efficiency (EQE) also were investigated. The Ag/ZnO/p-Si heterostructure exhibits good photodetection performance at all visible range of electromagnetic spectrum and can be good candidate for optoelectronic applications.

Gentle Perseverance Lifts the Veil on Martian Dust

AbstractObservations with sensitive photodiode detectors on the Perseverance rover (Hueso et al., 2023, https://doi.org/10.1029/2022JE007516; Vicente‐Retortillo et al., 2023, https://doi.org/10.1029/2022je007672) to detect dust devils and track formation, and movies of the Ingenuity helicopter's downwash impingement on the Martian surface (Lemmon et al., 2022a, https://doi.org/10.1029/2022je007605; Lemmon et al., 2022b, https://doi.org/10.1029/2022gl100126), together with in‐situ meteorological data, give new insights into the important problem of dust‐lifting on Mars, a phenomenon which influenced the lifetime of recent rovers and landers. These results, together with new low‐gravity wind tunnel experiments on parabolic flights and interpretation of the large blast pattern from lander retrorockets, indicate that particle motion and visible darkening on Mars can result from aerodynamic pressures of only 1–5 Pa, considerably less than previously thought.

A new trinuclear Cd(II)-based coordination polymer with Salen ligand building blocks: Synthesis, crystallographic aspects, and optimistic photosensitive Schottky barrier diode behaviour

A new X-ray-characterized Cd(II)-based coordination polymer has been synthesized using Salen ligand (H2L1) and dicyanamide ion (dca) [N(CN)2]−, and characterized using elemental analysis, spectroscopy, SEM/EDX, TEM, and powder X-ray diffraction techniques. According to SCXRD, the complex crystallizes in the triclinic space group P-1. The asymmetric unit includes de-protonated ligands [L]2−, Cd(II) centres, and dca ions. The complex binuclear parts are connected by two μ1,5-dca bridges, resulting in the creation of a one-dimensional coordination polymer [(L1Cd)2(μ1,5-dca)2Cd]n. The polymer undergoes supramolecular aggregation via hydrogen bonding, CH···π(dca), and CH···π(arene) interactions. Hirshfeld surfaces (HS) and 2D fingerprint plots have been deployed to visualize the supramolecular interactions. The analysis shows that N…H interactions (18.2%) are more common in the crystal packing than Cd···O/O···H. This complex displays electrical conductivity and photosensitivity properties, making it a promising material for optoelectronic applications. Experimental and DFT studies have confirmed that it is a direct semiconductor with a specific optical band gap (3.54 eV) and is also used to construct a photosensitive Schottky barrier diode (SBD). The DFT calculated optical conductivity was used to analyse how the material's conductivity changes upon illumination. Due to the photon absorption, the material's electrical conductivity and photoconductivity change were concomitantly observed. Finally, the DOS analysis explains the complex's conductivity behaviour in a better logistic way.

Fabrication of Schottky Barrier Diodes Utilizing Schiff Base Compounds and Metal Complexes with Schiff Base Ligands

AbstractFabrications of different kinds of diodes with various types of materials are the trends of modern research. In recent times organic materials and metal complexes containing organic ligands are chosen preferably for the fabrication of Schottky barrier diodes. Utilizations of Schiff‐base compounds and Schiff base containing metal complexes in the making of Schottky barrier diodes are immensely appreciated because the syntheses of Schiff‐base compounds are quite straightforward, less expensive and require less time. Large scale production of Schiff base materials is comparatively easier because their syntheses involve facile condensation reaction and their optical properties can be easily tuned by introducing simple substituent groups. Designing appropriate molecular structure plays pivotal role in the conducting properties of the materials. The molecular systems with exiting conducting properties can be utilized for the fabrication of such active electronic device. Sometimes, the specific structural arrangements enhance the charge flow upon illumination of light. These materials can be used in making photosensitive diode devices. In this context, this review, comprising of a collection of research articles regarding Schottky diode device based on Schiff bases and metal complexes with Schiff base ligands, may be helpful for the researchers of the relevant field.

Highly Efficient and Stable Self-Powered Perovskite Photodiode by Cathode-Side Interfacial Passivation with Poly(Methyl Methacrylate).

For several years now, organic-inorganic hybrid perovskite materials have shown remarkable progress in the field of opto-electronic devices. Herein, we introduce a cathode-side passivation layer of poly(methyl methacrylate) (PMMA) for a highly efficient and stable self-powered CH3NH3PbI3 perovskite-based photodiode. For effective noise-current suppression, the PMMA passivation layer was employed between a light-absorbing layer of CH3NH3PbI3 (MAPbI3) perovskite and an electron transport layer of [6,6]-phenyl-C61-butyric acid methyl ester. Due to its passivation effect on defects in perovskite film, the PMMA passivation layer can effectively suppress interface recombination and reduce the leakage/noise current. Without external bias, the MAPbI3 photodiode with the PMMA layer demonstrated a significantly high specific detectivity value (~1.07 × 1012 Jones) compared to that of a conventional MAPbI3 photodiode without a PMMA layer. Along with the enhanced specific detectivity, a wide linear dynamic response (~127 dB) with rapid rise (~50 μs) and decay (~17 μs) response times was obtained. Furthermore, highly durable dynamic responses of the PMMA-passivated MAPbI3 photodiode were observed even after a long storage time of 500 h. The results achieved with the cathode-side PMMA-passivated perovskite photodiodes represent a new means by which to realize highly sensitive and stable self-powered photodiodes for use in developing novel opto-electronic devices.

Study of Photodetectors with Schottky Barriers Based on the IrSi–Si Contact

A significant increase in the fill factor of Schottky matrices is achieved by reading the charge accu-mulated in the Schottky diode not by using charge-coupled device (CCD) registers but by injecting it into the signal bus, similarly to charge-injected device (CID) structures on narrow-gap semiconductors. In this case, the multielement matrix contains horizontal buses to poll the elements of the selected row, vertical signal lines, and a metal–oxide–semiconductor (MOS) switch for connecting the polled column and the matrix of photosensitive elements, each consisting of a photosensitive Schottky diode and a MOS switch.

Light intensity measurement using LabVIEW graphical programming environment

Abstract Lighting and light distribution have a crucial influence on factors such as performance and occupational safety. This paper aims to create a virtual instrument (VI), developed around the Arduino Uno development platform, designed to measure the light intensity using the BPW34 sensitive silicon PIN photodiode. The reverse-biased photodiode can be used as a light detector by monitoring the current flowing through it. Coupled to a 10Kohm resistor and considering the specifications of the BPW34 model, a simple relationship is offered between lux (light intensity) and the voltage across the resistance. The virtual instrument reads this voltage and converts it to a light intensity value in Lux. There is also an alarming function if the light intensity exceeds the set value. The VI also shows basic statistics like Max, Mean, and Min light intensity values.

Photosensitive Schottky diodes based on nanostructured thin films of graphitized carbon formed on Cd1− x Zn x Te crystalline substrates

Photosensitive Schottky diodes of graphite/n-Cd1−x Zn x Te were obtained by depositing thin films of graphitized carbon on crystalline substrates of n-Cd1−x Zn x Te solid solution by electron beam evaporation. Based on the analysis of the single-phonon Raman spectra, it was found that the obtained films can be considered as nanocrystalline carbon structures with crystallite sizes of La ≈ 4.8 nm. From the research on the temperature dependencies of the I–V-characteristics and frequency dependencies of the C–V-characteristics, the main parameters of the structure were determined as well as the role of surface energy states in the formation of the profile of energy zones in the contact area. The main mechanisms of the forward and reverse currents are established. Using the diffusion theory of rectification, the height of the potential barrier was calculated and found to coincide with the experimentally determined value. A model of the diode energy diagram is proposed, which accurately describes the experimental electrophysical phenomena. The photoelectric properties of the graphite/n-Cd1−x Zn x Te diodes were studied.

Si-based photosensitive diode with novel Zn-doped nicotinate/nicotinamide mixed complex interlayer

Al/Zn-complex/p-Si/Al metal-polymer-semiconductor (MPS) diode is deposited by using thermal evaporation technique for metal layers and spin-coating technique for polymer interface layer. Zn(C6H6N2O)2(C6H4NO2)2(H2O)].1/2(H2O) is prepared as a precursor material and different spin-coating solutions in terms of Zn-complex contribution (0.5, 1.0, 2.0 and 3.0 mg) are used in the film deposition process. The characterization of this precursor is provided by TEM imaging. In addition, deposited interface layers in different amount of Zn-complex in solution are investigated by AFM. Current-voltage (I−V), capacitance-voltage (C−V) and conductance-voltage (G−V) characteristics of the MPS diode are evaluated as a function of compositional change at the interface under dark and illumination conditions. Main diode parameters as barrier height, ideality factor and parasitic resistances are extracted from dark I−V curves and also they are discussed for the measurements under different illumination intensity. Capacitive behavior of these MPS diodes are observed by dark C−V and G−V measurements, and resistance values are also calculated from these results. The on/off illumination switching response of the diodes are observed from transient photo-current, photo-capacitance and photo-conductance plots.

A new approach to measure radon by Thick Gas Electron Multiplier

In this article, a novel approach to the use of the Micro Pattern Gas Detector (MPGD) to detect the radon gas contamination in air is presented. It consists in operating the Thick Gas Electron Multiplier (THGEM) in Self-Quenched Streamer (SQS) mode. This detector works based on counting alpha particles emitted from radon and its short-lived daughters, Po-218 and Po-214. If this detector is compared to a scintillation detector, its THGEM can be considered as a scintillator and conventional light sensors as photomultipliers or sensitive photodiodes. A laboratory layout of the recommended system was designed to measure radon concentration in air based on measuring the alpha emitted of radon and its short-lived daughters. One of the advantages of this detector over the scintillation and semiconductor detectors is a vast sensitive surface (5*5 cm2) uninfluenced by noises and background rays. The practical results show that this recommended detector uninfluenced by background rays has a very low limit of detection about zero. Consequently, this detector can measure very low radon gas concentrations in the air.

Production and Characterization of AlNiOZnOp-SiAl Composite Photodiodes for Solar Energy Tracking Systems

In present study, NiO:ZnO thin films in molar ratios of 1:0, 0:1, 3:1, 1:1 and 1:3 were formed on p-Si layers with aluminum (Al) bottom contact. Dynamic sol-gel spin coating method was used as coating method. Al top contacts were deposited on thin films and Al/NiO:ZnO/p-Si/Al photodiodes were fabricated. The structural and morphological properties of the photodiodes were determined by X-ray diffraction (XRD), emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX). The photoresponse and electrical properties of the produced photodiodes were investigated by current–voltage (I–V) and capacitance-voltage (C-V) measurements. Al/NiO:ZnO/p-Si/Al photodiodes were successfully produced. It was determined that the thin films formed were composed of nanostructures. All photodiodes were found to be sensitive to light. It was seen that the photosensitivity of composite photodiodes was higher than the pure photodiodes and photosensitivity decreased as the ZnO ratio increased. It was determined that the most sensitive photodiode to light was the composite photodiode with a NiO:ZnO ratio of 3:1, and the highest photosensitivity was measured as 3.12 x 103 at 100 mW/cm2 light intensity in this photodiode. In all photodiodes, the capacitance values decreased as the frequency increased. The results show that by changing the NiO:ZnO ratio, the photoresponse and electrical parameters of the photodiodes can be controlled and the produced photodiodes can be used as a photosensor in solar tracking systems and optoelectronic applications.

Photosensitive Schottky barrier diodes based on Cu/p-SnSe thin films fabricated by thermal evaporation

The photosensitive nature of a thermally evaporated Cu/p-SnSe thin film Schottky junction.