Nanostructured Photodetector Research Articles

Investigation of structural, optical, and electrical characterization of nanostructured Bi30Sb10Se60-based photodetector applications

This study thoroughly investigates the optical absorption properties of Bi30Sb10Se60 thin films, focusing on their applicability in photo-sensing technologies. By employing a range of spectrophotometric techniques, including transmission and reflection analyses, the research identifies a direct energy gap of 1.68 eV, along with dispersion and oscillator energies of 14.36 eV and 3.42 eV, respectively. These parameters reveal the material's interaction capabilities with light. The study highlights the heterojunction's pronounced photosensitivity, especially at lower reverse biases, indicating its promise for photo-sensing applications. Photoluminescence (PL) spectra show broad defect emission bands with peaks at 475 nm, 487 nm, 510 nm, and 525 nm, which provide insights into recombination processes. Additionally, Energy Dispersive Spectroscopy (EDS) confirms the films' near-stoichiometric composition, while Thermal Gravimetric Analysis (TGA) demonstrates the high thermal stability of the films. The findings include high responsivity and detectivity of the photodetector, though the linear dynamic range (LDR) and signal-to-noise ratio (SNR) are comparatively lower. Overall, the research advances the understanding of Bi30Sb10Se60 thin films, paving the way for their use in optimized photoresponsive devices within optoelectronic technologies.

Passivation-free high performance self-powered photodetector based on Si nanostructure-PEDOT:PSS hybrid heterojunction

Hybrid heterojunction between organic PEDOT:PSS and inorganic Silicon (Si) nanostructures is promising for high-performance self-powered photodetectors due to their favourable band energetics and ease of processing. Traditionally, Si nanostructures require additional passivation layers to reduce surface defect states, which adds complexity and involves the use of harmful organic solvents. Here in, we demonstrate a simple chemical polishing process to reduce defects and fabricate a conformable heterojunction between Si nanostructures and PEDOT:PSS. Si nanostructures fabricated by metal-assisted chemical etching (MACE) technique and subsequently treated by the chemical polishing process are spin-coated with PEDOT:PSS to form heterojunction and employed as self-powered broadband photodetector. The optimized device shows superior performance, such as high responsivity of 555.34 mA/W, quick rise/fall times of 79 ms/81 ms, high External Quantum Efficiency (EQE) of 0.8 at zero bias (0 V) and high photostability up to 500 illumination cycles. Dark I-V characteristics and carrier lifetime measurements reveal that the enhanced performance of chemically polished devices is attributed to the formation of a conformable heterojunction and reduction in defects in the Si nanostructures. Given the scalability and simplicity of the demonstrated passivation-free approach, this work may aid the fabrication of high-performance hybrid Si nanostructured photodetectors.

Recent advances in two-dimensional graphitic carbon nitride based photodetectors

Graphitic carbon nitride (g-C3N4) is a kind of low cost and environment-friendly 2D polymer semiconductor that exhibits a tunable band gap, high thermal stability, intriguing optoelectronic properties and broad device applications. However, there is hardly any review of g-C3N4′s recent development in photodetection devices. Herein, we summarized the recent advances in the 2D g-C3N4 based photodetector. Firstly, the structure and optoelectronic properties of 2D g-C3N4 were introduced. Secondly, recent progress in 2D g-C3N4 based photodetectors with different device types, such as 2D g-C3N4 based photoconductor, hybrid nanostructure photodetector, photodiode, perovskite photodetector and piezo-phototronic photodetector were summarized. Finally, some major challenges and opportunities towards the practical optoelectronic device applications of 2D g-C3N4, which need be further investigated, had been discussed. As a pioneer, this review systematically presented the development of 2D g-C3N4 based photodetector in the past years and highlighted their great potential in field of broadband, low-cost, fast-response and high-performance photodetectors. We hope that this review could guide the following development and research of g-C3N4 based photodetectors.

Space-charge-limited current activation in self-powered and solar-range nanostructured Cu3Se2 photodetector by Zn concentrations

In this research, the impact of the different zinc (Zn) concentrations on the physical and optoelectronic properties of copper selenide (Cu3Se2) nanostructures as self-powered and solar-range photodetector applications was investigated. The obtained results indicated the formation of a tetragonal Cu3Se2 phase with a spherical-like morphology. All the samples showed Cu-poor stoichiometry, and the incorporation of the Zn atoms in the Cu3Se2 lattice decreased the optical energy band gap. It was observed that Zn concentrations activated the space-charge-limited conduction (SCLC) mechanism in the Cu3Se2 devices. The band alignments and barrier potentials at different interfaces were studied for understanding the observed transportation mechanism. Finally, it was found that the Zn-doped sample with the highest amount of Zn concentration showed the highest values of the responsivity (R), gain (G), and specific detectivity (D*) in the amounts of 0.127 mA/W, 21.77%, and 3.92 × 10+8 Jones, respectively.

Enhanced performance of visible-range nanostructured CuS photodetectors by Zn concentrations

This research investigates the physical and electrical properties of copper sulfide (CuS) nanostructures grown using the sonochemical method. The effect of adding zinc (Zn) dopant in different concentrations was studied through various analyses. X-ray diffraction (XRD) pattern analysis revealed that CuS samples exhibit a hexagonal covellite structure, and the presence of the dopant increases the strain on the crystal lattice of CuS. Transmission electron microscope (TEM) images demonstrated a decrease in the size of CuS nanostructures with the addition of Zn dopant atoms. Optical analyses indicated that the absorption intensity increases and the intensity of photoluminescence emissions decrease with the addition of Zn dopant in different concentrations. Furthermore, the addition of Zn concentrations improved the electrical properties of CuS. Ultimately, it was observed that the quality parameters of the photodetector improved in Zn-doped samples due to enhancements in physical and electrical properties.

High Performance of Nanostructured Cu2O-Based Photodetectors Grown on a Ti/Mo Metallic Substrate

In this work, cuprous oxide (Cu2O) thin films were prepared using a simplistic sputtering technique. The films were grown on both traditional fluorine-doped tin oxide (FTO) and Ti-metallic substrates. X-ray diffraction applied for investigation of the crystal structure proved that the Cu2O layer acquires the cubic structure with a (111) main peak at 2θ of 36.46°. The optical absorption and transmission were detected through the utilization of a UV-Vis spectrophotometer, and the optical bandgap for the Cu2O layer was determined to be ~2.15 eV using Tauc’s equation. XPS and scanning electron microscopy were also performed for chemical structure and morphological investigation, respectively. The optoelectronic behaviors for the prepared samples were carried out using a Keithley source meter; the photocurrent density was measured in a range of applied voltage between −1 and 1 volt under the illumination of a xenon lamp with a power density of 100 mWcm−2. External quantum efficiency, sensitivity, responsivity, and detectivity were computed using proprietary models based on the experimental data.

Highly Efficient Visible-Blind Ultraviolet Photodetector Based on Scalably Produced Titanium Dioxide Nanowire Arrays.

Here, we report a novel, feasible, and cost-effective method for the preparation of one-dimensional TiO2 nanowire arrays using a super-aligned carbon nanotube film as a template. Pure-anatase-phase TiO2 nanowires were scalably prepared in a suspended manner, and a high-performance ultraviolet (UV) photodetector was realized on a flexible substrate. The large surface area and one-dimensional nanostructure of the TiO2 nanowire array led to a high detectivity (1.35 × 1016 Jones) and an ultrahigh photo gain (2.6 × 104), respectively. A high photoresponsivity of 7.7 × 103 A/W was achieved under 7 μW/cm2 UV (λ = 365 nm) illumination at a 10 V bias voltage, which is much higher than those of commercial UV photodetectors. Additionally, by taking advantage of its anisotropic geometry, we found the TiO2 nanowire array showed polarized photodetection. The concept of using nanomaterial systems shows the potential for realization of nanostructured photodetectors for practical applications.

Ag-Nanoparticle-Coupled UV-Responsive Gelatin Nanofiber Photodetectors

In this era of environmental protection and performance, the development of organic photodetectors is booming. The hydrogel material is beginning to attract attention because of its characteristics such as plasticity and ecofriendliness. However, it is still a challenge to achieve a high-speed response in biophotodetectors. Herein, the development of an organic one-dimensional nanostructured photodetector is proposed through rotary-jet injection of gelatin fibers incorporated with silver nanoparticles (Ag NPs). The variation in the photoelectric properties of thin-film, fibrous structures with different diameters of approximately 40 μm and 400 nm has been investigated. In particular, the gelatin–Ag NPs fiber photoreceptor with a diameter of about 400 nm improved the light-to-dark current ratio by up to 28000% higher than the film structure, with rise and decay times of only 0.23 and 0.56 s. In addition, the nanostructure effectively boosts the photocurrent and suppresses the dark current because of its confining domains. The Ag NPs within the gelatin nanofibers produce localized surface plasmon resonance in the UV-illumination environment, enhancing the light absorption of the photosensitive layer, which contributes directly to the increase in the rate of excitons. The novel structure of the hybridized gelatin nanofibers incorporating silver nitrate has offered the promising potential for organic photodetectors.

Recent Advances in Si-Compatible Nanostructured Photodetectors

In this review the latest advances in the field of nanostructured photodetectors are considered, stating the types and materials, and highlighting the features of operation. Special attention is paid to the group-IV material photodetectors, including Ge, Si, Sn, and their solid solutions. Among the various designs, photodetectors with quantum wells, quantum dots, and quantum wires are highlighted. Such nanostructures have a number of unique properties, that made them striking to scientists’ attention and device applications. Since silicon is the dominating semiconductor material in the electronic industry over the past decades, and as germanium and tin nanostructures are very compatible with silicon, the combination of these factors makes them the promising candidate to use in future technologies.

Monolithic InSb nanostructure photodetectors on Si using rapid melt growth.

Monolithic integration of InSb on Si could be a key enabler for future electronic and optoelectronic applications. In this work, we report the fabrication of InSb metal-semiconductor-metal photodetectors directly on Si using a CMOS-compatible process known as rapid melt growth. Fourier transform spectroscopy demonstrates a spectrally resolved photocurrent peak from a single crystalline InSb nanostructure with dimensions of 500 nm × 1.1 μm × 120 nm. Time-dependent optical characterization of a device under 1550 nm illumination indicated a stable photoresponse with responsivity of 0.50 A W-1 at 16 nW illumination, with a time constant in the range of milliseconds. Electron backscatter diffraction spectroscopy revealed that the single crystalline InSb nanostructures contain occasional twin defects and crystal lattice twist around the growth axis, in addition to residual strain, possibly causing the observation of a low-energy tail in the detector response extending the photosensitivity out to 10 μm wavelengths (0.12 eV) at 77 K.

Hierarchical zinc oxide nanobrushes ultraviolet photodetector

In order to synthesise hierarchical zinc oxide (ZnO) nanomaterials with a high surface-to-volume ratio, a well-controlled multistage hydrothermal method was developed. Hierarchical ZnO nanobrushes (ZNBs) built from initial mono-morphological nanomaterials, ZnO nanowires (ZNWs), and ZnO nanoplates (ZNPs) were developed using sequential nucleation and growth following a hydrothermal process. Hierarchical nanomaterials which are comprised of one-dimensional (1D) nanowire building blocks were obtained via a zinc ion source (zinc nitrate) during the second growth phase. In comparison to their first mono-morphological equivalents, the hierarchical nanomaterials which were grown showed improved ultraviolet (UV) detection, as well as improved sensitivity (∼104), an ultra-fast response time (235 ms), and a good recovery time (310 ms). Improvements to the response and recovery times were a result of distinct nanojunction barrier-dominated resistance. Moreover, the enhanced sensitivity of the ZNB photodetector (PD) was because of the reduced dimensionality and the ultrahigh surface-to-volume ratio. This work lays the groundwork for lower-cost, larger-scale, and lower-temperature production of high-performance nanostructured ZnO-based PDs on transparent and flexible substrates.

Small-diameter p-type SnS nanowire photodetectors and phototransistors with low-noise and high-performance

P-type nanostructured photodetectors and phototransistors have been widely used in the field of photodetection due to their excellent electrical and optoelectronic characteristics. However, the large dark current of p-type photodetectors will limit the detectivity. Herein, we synthesized small-diameter single-crystalline p-type SnS nanowires (NWs) and then fabricated single SnS NW photodetectors and phototransistors. The device exhibits low noise and low dark current, and its noise current power is as low as 2.4 × 10−28 A2. Under 830 nm illumination and low power density of 0.12 mW cm−2, the photoconductive gain, responsivity and detectivity of the photodetector are as high as 3.9 × 102, 2.6 × 102 A W−1 and 1.8 × 1013 Jones, respectively, at zero gate voltage. The rise and fall time of response are about 9.6 and 14 ms. The experimental results show that the small-diameter p-type SnS NWs have broad application prospects in high-performance and low-power photodetectors with high sensitivity, fast response speed and wide spectrum detection in the future.

Low-power supralinear photocurrent generation via excited state fusion in single-component nanostructured organic photodetectors

Columnar arrangement of triplet emitters in the photoactive layer of vertically-configured photodetectors enables photocurrent generation via triplet–triplet annihilation of dimer species.

Nanostructured Materials and Architectures for Advanced Optoelectronic Synaptic Devices

AbstractNeuromorphic photonics system based on the principle of biological brain is emerging as one of the potential solutions to the bottleneck inherent in classical von Neumann computing system. Optoelectronic synaptic devices, used to mimic the visual function of bio‐synapse by adapting synaptic weights, can construct a highly efficient brain‐inspired computing system, in which the nanostructured materials and device architectures are attracting extensive interests, giving many potential benefits in confined light‐matter interaction, fast carrier dynamics, and photocarriers trapping. Moreover, the conjunction of traditional nanostructured photodetectors and newly realized electronic synapses also exhibit appealing performance for many practical applications including information processing and computing. This review focuses and summarizes on recent achievement in developing advanced optoelectronic synaptic devices based on nanostructured materials as 0D (quantum dots), 1D, and 2D materials, as well as, the rapidly evolving hybrid heterostructures. In addition, challenges and promising prospects in this research field are also discussed.

Chemical growth and study of low intensity sensing ability of nanobranch and nanorod structured SnO2 UV detector

Ultra violet (UV) photodetector (PD) has been gaining attention in the fields of environment, medical, civil, and military realms, etc. In this report, nanostructured tin oxide (SnO2) thin films were deposited by a hot-wall nebulizer spray pyrolysis technique. The nanostructured SnO2 UV PDs were fabricated. The structural, optical, and surface morphological properties have been investigated using the characterizing techniques of XRD, UV, PL spectrophotometer, and FESEM, respectively. The growth mechanism of structural transformation from nanobranch (Nb) to nanorod (NR) structure was discussed extensively. The photoelectric properties of the fabricated devices were performed under UV light (365 nm wavelength). The PD devices responded to two bias voltage ranges of 0.0004 V and 0.5 V for Nb and NR devices, respectively. The reason behind its due to the influence of surface states in the material that has been explained. Based on the results, the as-fabricated devices detect low light intensity in the microwatt power range. The transient photoresponse profiles exhibit the abundant surface states formation in nanostructures which showed as persistent photocurrent. Quenching of photocurrent for NR PD was observed at 0.5 bias voltage. We attained large photosensitivity and low bias sensing ability of SnO2 PD devices which clearly indicate that the possibility of the development of environment monitor supported self-powered devices.

High performance conical nanostructured GaN-based photodetectors

Here, we report on a new type of conical nanostructured GaN (CNG), and the corresponding high performance GaN-based metal–semiconductor–metal (MSM) photodetectors (PDs). Compared with the control planar GaN-based MSM PDs, the photocurrent increases by ∼600 times at 0.4 V. The responsivity of the CNG-based PDs can reach ∼2 × 104 A W−1 at 4 V, increased by ∼2000 times compared to the planar GaN-based PDs. The specific detectivity of the CNG-based PDs reaches the maximum at 1 V, ∼1014 Jones, which is more than 800 times to that of the planar GaN-based PDs. Our work paves the way to develop high-performance GaN-based PDs using a new nanostructure for detecting weak optical signals.

Methodology of optimisation for a nanostructured two-photon absorption photodetector

We introduce a 3-step method to optimise a nanostructured photodetector for infrared sensing through non degenerated two-photon absorption (NDTPA). First, the nanostructure is designed to tailor the distribution and concentration of both pump and signal intensities within the absorbing layer, thus leading to a gain in two-photon absorption. Second, the issue of the competition between NDTPA and other sub-bandgap transitions is tackled with a new figure of merit to favor as much as possible NDTPA while minimising other absorption processes. Third, a refined computation of the gain and the figure of merit is done to consider focused beams. Finally, two scenarios based on low power infrared photodetection are investigated to illustrate the flexibility and adaptibility of the method. It is shown that the gain is up to 7 times higher and the figure of merit is up to 20 times higher compared to the literature.

Single-nanowire silicon photodetectors with core-shell radial Schottky junction for self-powering application

A silicon (Si) based core-shell single-nanowire photodetector with the radially configured Schottky junction is presented for high-performance self-powering photodetection application. The optoelectronic properties of the device are evaluated by performing a comprehensive device-level simulation using the finite-element method. An extremely high responsivity of 107 A/W at zero bias is predicted, which is three orders higher than that of the axially configured device. Additionally, the time-dependent simulation reveals that the system with the radial semiconductor junction shows a fast response with an unbiased response time of 22 μs. We explore detailedly the underlying mechanisms for the high-performance responses of this nanostructured photodetector. It is found that the single-nanowire design with the radial junction enables a high light absorption in optical domain as well as a very efficient and fast carrier transport in electrical domain.

Recent advances in development of nanostructured photodetectors from ultraviolet to infrared region: A review

Herein, we aim to evaluate the photodetector performance of various nanostructured materials (thin films, 2-D nanolayers, 1-D nanowires, and 0-D quantum dots) in ultraviolet (UV), visible, and infrared (IR) regions. Specifically, semiconductor-based metal oxides such as ZnO, Ga2O3, SnO2, TiO2, and WO3 are the majority preferred materials for UV photodetection due to their broad band gap, stability, and relatively simple fabrication processes. Whereas, the graphene-based hetero- and nano-structured composites are considered as prominent visible light active photodetectors. Interestingly, graphene exhibits broad band spectral absorption and ultra-high mobility, which derives graphene as a suitable candidate for visible detector. Further, due to the very low absorption rate of graphene (2%), various materials have been integrated with graphene (rGO-CZS, PQD-rGO, N-SLG, and GO doped PbI2). In the case of IR photodetectors, quantum dot IR detectors prevails significant advantage over the quantum well IR detectors due to the 0-D quantum confinement and ability to absorb the light with any polarization. In such a way, we discussed the most recent developments on IR detectors using InAs and PbS quantum dot nanostructures. Overall, this review gives clear view on the development of suitable device architecture under prominent nanostructures to tune the photodetector performance from UV to IR spectral regions for wide-band photodetectors.

Comparison of absorption simulation in semiconductor nanowire and nanocone arrays with the Fourier modal method, the finite element method, and the finite-difference time-domain method

For the design of nanostructured semiconductor solar cells and photodetectors, optics modelling can be a useful tool that reduces the need of time-consuming and costly prototyping. We compare the performance of three of the most popular numerical simulation methods for nanostructure arrays: the Fourier modal method (FMM), the finite element method (FEM) and the finite-difference time-domain (FDTD) method. The difference between the methods in computational time can be three orders of magnitude or more for a given system. The preferential method depends on the geometry of the nanostructures, the accuracy needed from the simulations, whether we are interested in the total, volume-integrated absorption or spatially resolved absorption, and whether we are interested in broadband or narrowband response. Based on our benchmarking results, we provide guidance on how to choose the method.