Single Nanowire Photodetector Research Articles

Photoelectronic properties of antimony selenide nanowire synthesized by hydrothermal method

With the advantages of stable structure, large optical absorption coefficient, optimal bandgap, and high See-Beck coefficient, antimony selenide (Sb2Se3) has good prospects for applications in solar cells, photodetectors, thermoelectric devices, etc. In this work, high quality Sb2Se3 nanowires were fabricated by a hydrothermal method and the fabrication of a single nanowire photodetector was reported. From the experimental data, a band gap of Sb2Se3 nanowires was calculated to be 1.04 eV. The Sb2Se3 single nanowire detector has a dark current of 230 pA, a photocurrent of 45 nA, and a photoresponsivity of 196 mA/W under the light irradiation intensity of 14.4 mW/cm2 @ 532 nm. The photoresponse time of PDs is observed to be 90 ms and 100 ms. The results could enable the large-scale synthesis of high-purity Sb2Se3 nanowires with excellent optical properties and their application in functional optoelectronic devices.

Controlled growth of high-quality Bi2S3 nanowires and their application in near-infrared photodetection

A study on the chemical vapor deposition growth of monocrystalline Bi2S3 nanowires and their applications in near-infrared polarized photodetectors are reported. High-quality Bi2S3 nanowires were obtained with a maximum length of 14 μm and a minimum diameter of 35 nm. A growth model was also developed to explain the morphology change with respect to growth parameters which including precursor temperature, growth time, carrier gas flow rate, and inner tube pressure, leading to a better understanding of their growth mechanism. Photodetectors based on Bi2S3 single nanowires presented remarkable device performance with a responsivity of 4.21 A/W, a specific detectivity of 1.64 × 1010 Jones, an external quantum efficiency of 981.76%, and a photoresponse rate of 12.25 ms under the illumination of an 830 nm laser at room temperature (300 K). Under room temperature conditions, the Bi2S3 single nanowire photodetector also showed high polarization sensitivity to near-infrared light signals with a high dichroic ratio of 1.79. Based on these results, it indicates that Bi2S3 nanowires have a substantial portion of promise for near-infrared polarized photodetectors.

High-responsivity broadband photodetector fabricated using anodic aluminum oxide template-assisted grown β-InSe nanowires via focused ion beam deposition

Monocrystalline InSe nanowires with a [100] growth direction were prepared via vacuum hydraulic pressure injection using an anodic aluminum oxide (AAO) template at low temperature (650 °C). The lengths and diameters of the nanowires were tens of micrometers and ~100 nm, respectively. The AAO template-assisted grown β-InSe nanowires were used to fabricate a Pt-contacted single-nanowire photodetector using focused ion beam (FIB) deposition. The low dark current (several picoamperes) and ohmic contact of the Pt-contacted single-β-InSe nanowire photodetector resulted in rapid rise and fall times and high responsivity (R). The device exhibited a high R with a value of 1497 AW−1 under a 405 nm irradiation at 2 mW/cm2 and bias voltage of 1.0 V. The rapid rise and fall times of the FIB-deposited Pt-contacted single-β-InSe nanowire photodetector were 14 and 29 ms, respectively. These values are better than the respective values of 50 and 75 ms obtained using Au-contacted photodetectors fabricated via electron-beam lithography. The FIB-fabricated β-InSe nanowire device acted as a high-responsivity broadband photosensor (405–785 nm).

3D Meniscus‐Guided Evaporative Assembly for Rapid Template‐Free Synthesis of Highly Crystalline Perovskite Nanowire Arrays

AbstractLow‐dimensional nanostructures of halide perovskites have been receiving extensive research interest for their superior optical, electrical, and stability characteristics over their conventional bulk counterparts. In particular, the unique surficial characteristics of well‐defined 1D nanowires have shown high feasibility for high performance optoelectronic applications. The key aspect of endorsing this nanoscale form factor in practical applications lies in securing dimensional uniformity and controllability in large scales, which generally requires complicated lithographic procedures. In this work, a simple, rapid, and widely applicable strategy for the direct synthesis and printing of well‐aligned nanowire arrays on a large scale is demonstrated. By employing blade coating methods with sophisticatedly controlled stick‐slip motions, periodically resolved transverse 3D meniscus enables uniform directional growth of highly crystalline CsPbI3 nanowires without the need for templates. A systematic investigation of morphological evolutions with respect to kinetic processing variables is conducted, along with a comprehensive suite of structural and optical analyses for the synthesized nanowire arrays. A single nanowire photodetector is employed to demonstrate the superiority and applicability of the fabrication strategy. Finally, a 2D image recognition is demonstrated by using an array of photodetectors fabricated via a fast (<2 min) direct printing of nanowire arrays on wafers.

Preparation of functional Ga2S3 and Ga2Se3 shells around Ga2O3 nanowires via sulfurization or selenization

Combining defect semiconductors Ga2S3 and Ga2Se3 in Ga2O3-based heterostructured nanowires (NWs) have potential in photonics and optoelectronics applications due to the materials appealing optical properties. In this work, we have developed and studied Ga2O3–Ga2S3 and, for the first time, Ga2O3–Ga2Se3core-shell NWs. Ga2S3 and Ga2Se3 shell was obtained during high-temperature sulfurization and selenization process of pure Ga2O3 NWs, respectively, in a chemical vapour transport reactor. As-grown nanostructures were characterized with scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence measurements. Single-nanowire photodetector devices were fabricated in order to demonstrate their electric and photoconductive properties. Such novel core-shell NW heterostructures could potentially be used in next-generation nanoscale electronic and optoelectronic devices.

Ultrathin Sb2Se3 Nanowires for Polarimetric Imaging Photodetectors with a High Signal/Noise Ratio

AbstractThis work presents a study on the optical applications of chemical vapor deposition‐grown Sb2Se3 nanowires in polarized single nanowire photodetectors. High‐quality Sb2Se3 nanowires are obtained with diameters as small as ≈15 nm, which is the first report for ultrathin Sb2Se3 nanowires. The fabricated Sb2Se3 nanowire‐based photodetector presents a low shot noise of ≈ 9 × 10–16 A Hz–1/2, a large signal/noise ratio of 1436.55, a high responsivity of 3.61 A W–1, and a high specific detectivity of 2.36 × 1011 Jones, which can be attributed to the high‐quality crystalline nanowires obtained. More interestingly, the Sb2Se3 nanowire‐based photodetectors exhibit broadband polarized photoresponse to incident light with wavelengths ranging from visible to near‐infrared (532 – 830 nm). A linearly dichroic ratio of 1.71 is obtained for the 830 nm light illumination. The Sb2Se3 nanowire detectors also present appropriate polarimetric imaging quality, revealing the potential of Sb2Se3 nanowires for polarimetric imaging applications.

Ge–Ge0.92Sn0.08 core–shell single nanowire infrared photodetector with superior characteristics for on-chip optical communication

Recent development on Ge1−xSnx nanowires with high Sn content, beyond its solid solubility limit, makes them attractive for all group-IV Si-integrated infrared photonics at the nanoscale. Herein, we report a chemical vapor deposition-grown high Sn-content Ge–Ge0.92Sn0.08 core–shell based single nanowire photodetector operating at the optical communication wavelength of 1.55 μm. The atomic concentration of Sn in nanowires has been studied using x-ray photoelectron and Raman spectroscopy data. A metal–semiconductor–metal based single nanowire photodetector, fabricated via an electron beam lithography process, exhibits significant room-temperature photoresponse even at zero bias. In addition to the high-crystalline quality and identical shell composition of the nanowire, the efficient collection of photogenerated carriers under an external electric field results in the superior responsivity and photoconductive gain as high as ∼70.8 A/W and ∼57, respectively, at an applied bias of −1.0 V. The extra-ordinary performance of the fabricated photodetector demonstrates the potential of GeSn nanowires for future Si CMOS compatible on-chip optical communication device applications.

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.

Effective Separation of Photogenerated Electron–Hole Pairs by Radial Field Facilitates Ultrahigh Photoresponse in Single Semiconductor Nanowire Photodetectors

We report an investigation on the observation of ultrahigh photoresponse (photogain, G_Pc>106) in single nanowire photodetectors of diameter < 100 nm. The investigation which is a combination of experimental observations and a theoretical analysis of the ultrahigh optical response of semiconductor nanowires, has been carried out with emphasis on Ge nanowires. Semiconductor nanowire photodetectors show a signature of photogating where G_Pc rolls-off with increasing illumination intensity. We show that surface band bending due to depleted surface layers in nanowires induces a strong radial field (~ 108 V/m at the nanowire surface) which causes physical separation of photogenerated electron-hole pairs. This was established quantitatively through a self-consistent theoretical model based on coupled Schrodinger and Poisson Equations. It shows that carrier separation slows down the surface recombination velocity to a low value (< 1 cm/s) thus reducing the carrier recombination rate and extending the recombination lifetime by few orders of magnitude. An important outcome of the model is the prediction of G_Pc ~ 106 in a single Ge nanowire (with diameter 60 nm), which matches well with our experimental observation. The model also shows an inverse dependence of G_Pc on the diameter that has been observed experimentally. Though carried out in context of Ge nanowires, the physical model developed has general applicability in other semiconductor nanowires as well.

Review on III-V Semiconductor Single Nanowire-Based Room Temperature Infrared Photodetectors.

Recently, III-V semiconductor nanowires have been widely explored as promising candidates for high-performance photodetectors due to their one-dimensional morphology, direct and tunable bandgap, as well as unique optical and electrical properties. Here, the recent development of III-V semiconductor-based single nanowire photodetectors for infrared photodetection is reviewed and compared, including material synthesis, representative types (under different operation principles and novel concepts), and device performance, as well as their challenges and future perspectives.

Growth and characterization of PbI2-decorated ZnO nanowires for photodetection applications

In this study, we demonstrated for the first time the growth of ZnO nanowires (NWs) decorated with highly crystalline few-layer PbI2 and fabricated two-terminal single-nanowire photodetector devices to investigate the photoelectric properties of the hybrid nanostructures. We developed a novel two-step growth process for uniform crystalline PbI2 nanosheets via reactive magnetron deposition of a lead oxide film followed by subsequent iodination to PbI2 on a ZnO NW substrate, and we compared as-grown hybrid nanostructures with ones prepared via thermal evaporation method. ZnO–PbI2 NWs were characterized by scanning and transmission electron microscopy, X-ray diffraction analysis and photoluminescence measurements. By fabricating two-terminal single-nanowire photodetectors of the as-grown ZnO–PbI2 nanostructures, we showed that they exhibit reduced dark current and decreased photoresponse time in comparison to pure ZnO NWs and have responsivity up to 0.6 A/W. Ab initio calculations of the electronic structure of both PbI2 nanosheets and ZnO NWs have been performed, and show potential for photoelectrocatalytic hydrogen production. The obtained results show the benefits of combining layered van der Waals materials with semiconducting NWs to create novel nanostructures with enhanced properties for applications in optoelectronics or X-ray detectors.

Effect of Bias on the Response of GaN Axial p-n Junction Single-Nanowire Photodetectors.

We present a comprehensive study of the performance of GaN single-nanowire photodetectors containing an axial p-n junction. The electrical contact to the p region of the diode is made by including a p+/n+ tunnel junction as cap structure, which allows the use of the same metal scheme to contact both ends of the nanowire. Single-nanowire devices present the rectifying current-voltage characteristic of a p-n diode but their photovoltaic response to ultraviolet radiation scales sublinearly with the incident optical power. This behavior is attributed to the dominant role of surface states. Nevertheless, when the junction is reverse biased, the role of the surface becomes negligible in comparison to the drift of photogenerated carriers in the depletion region. Therefore, the responsivity increases by about 3 orders of magnitude and the photocurrent scales linearly with the excitation. These reverse-biased nanowires display decay times in the range of ∼10 μs, limited by the resistor-capacitor time constant of the setup. Their ultraviolet/visible contrast of several orders of magnitude is suitable for applications requiring high spectral selectivity. When the junction is forward biased, the device behaves as a GaN photoconductor with an increase of the responsivity at the price of a degradation of the time response. The presence of leakage current in some of the wires can be modeled as a shunt resistance which reacts to the radiation as a photoconductor and can dominate the response of the wire even under reverse bias.

Metasurface Mirrors for External Control of Mie Resonances.

The ability to control and structurally tune the optical resonances of semiconductor nanostructures has far-reaching implications for a wide range of optical applications, including photodetectors, (bio)sensors, and photovoltaics. Such control is commonly obtained by tailoring the nanostructure's geometry, material, or dielectric environment. Here, we combine insights from the field of coherent optics and metasurface mirrors to effectively turn Mie resonances on and off with high spatial control and in a polarization-dependent fashion. We illustrate this in an integrated device by manipulating the photocurrent spectra of a single-nanowire photodetector placed on a metasurface mirror. This approach can be generalized to control spectral, angle-dependent, absorption, and scattering properties of semiconductor nanostructures with an engineered metasurface and without a need to alter their geometric or materials properties.

Effect of the nanowire diameter on the linearity of the response of GaN-based heterostructured nanowire photodetectors

Nanowire photodetectors are investigated because of their compatibility with flexible electronics, or for the implementation of on-chip optical interconnects. Such devices are characterized by ultrahigh photocurrent gain, but their photoresponse scales sublinearly with the optical power. Here, we present a study of single-nanowire photodetectors displaying a linear response to ultraviolet illumination. Their structure consists of a GaN nanowire incorporating an AlN/GaN/AlN heterostructure, which generates an internal electric field. The activity of the heterostructure is confirmed by the rectifying behavior of the current–voltage characteristics in the dark, as well as by the asymmetry of the photoresponse in magnitude and linearity. Under reverse bias (negative bias on the GaN cap segment), the detectors behave linearly with the impinging optical power when the nanowire diameter is below a certain threshold (≈80 nm), which corresponds to the total depletion of the nanowire stem due to the Fermi level pinning at the sidewalls. In the case of nanowires that are only partially depleted, their nonlinearity is explained by a nonlinear variation of the diameter of their central conducting channel under illumination.

Synthesis of SnO2 Nanowires Using SnI2 as Precursor and Their Application as High‐Performance Self‐Powered Ultraviolet Photodetectors

SnO2 nanowires are synthesized by chemical vapor deposition using elemental tin or SnI2 as tin precursors. The latter is found to be more controllable for the synthesis of SnO2 nanostructures. X‐ray diffraction analysis reveals that the SnO2 nanowires exhibit rutile crystal structure. Single nanowire photodetectors are processed, which show high responsivities, high external quantum efficiencies, and fast response times at nominal zero bias. The excellent device performance is attributed to the small size and high crystalline quality of the nanowire.

The way to high-performance single nanowire photodetectors: problems and prospects

The way to high-performance single nanowire photodetectors: problems and prospects

Self-catalyzed molecular beam epitaxy growth and their optoelectronic properties of vertical GaAs nanowires on Si(111)

Self-assembled GaAs nanowires were grown by molecular beam epitaxy (MBE) on un-pretreated Si(111) substrates under different As4/Ga flux ratios (V/III ratios). It has been found that the fraction of vertical wires would be nearly 100% when the As4/Ga ratio arrives 90. The transmission electron microscopy (TEM) and micro-photoluminescence (PL) spectra results have indicated that the GaAs nanowires grown under a larger V/III ratio (90) have a pure ZB structure. Field-effect transistors (FET) based on single nanowire were fabricated with GaAs nanowires grown under the larger V/III ratio (90). The characteristics of the FET reveal a hole concentration of 3.919×1017cm−3 and a hole mobility of 0.417cm2V−1s−1. Photodetectors based on single nanowire and multiple nanowires structure with a metal-semiconductor-metal (MSM) electrode configuration have been proposed and demonstrated. All the photodetectors operating at room temperature exhibit good photoconductive performance, excellent stability, reproducibility and superior peak responsivity (87.67A/W under 5V for single nanowire photodetector).

Bandgap-engineered GaAsSb alloy nanowires for near-infrared photodetection at 1.31 μm

Single-nanowire photodetectors have potential applications in integrated optoelectronic devices and systems. Here, bandgap-engineered GaAs0.26Sb0.74 alloy nanowires were synthesized via a chemical vapor deposition method. The synthesized nanowires are single crystals grown along the [111]B direction with length up to 50 μm and diameter ranging from 40 to 500 nm. Photodetectors are built based on these single-alloy nanowires, which show a wide response in the near-infrared region with a high response peak located in the optical communication region (1.31 μm), as well as an external quantum efficiency of 1.62 × 105%, a responsivity of 1.7 × 103 A W−1 and a short response time of 60 ms. These novel near-infrared photodetectors may find promising potential applications in integrated infrared photodetection, thermal imaging, information communication and processing.

High-performance rigid and flexible ultraviolet photodetectors with single-crystalline ZnGa2O4 nanowires

ZnGa2O4 nanowires (NWs) as a ternary oxide semiconductor were successfully synthesized by a simple vapor transport method for application as highperformance ultraviolet (UV) photodetectors. A single-nanowire UV photodetector fabricated on a rigid silicon substrate exhibited excellent spectral responsivity (3,174 A/W) and high external quantum efficiency (1.1 × 106%) at 350 nm UV light illumination. A flexible single-nanowire photodetector on a polyethylene terephthalate (PET) substrate was also fabricated and showed similar properties. The as-fabricated flexible photodetector exhibited stable electrical properties and mechanical flexibility under different bending curvatures over many cycles, indicating its potential application in future flexible photoelectronic devices.

Coaxial Ag/ZnO/Ag nanowire for highly sensitive hot-electron photodetection

Single-nanowire photodetectors (SNPDs) are mostly propelled by p-n junctions, where the detection wavelength is constrained by the band-gap width. Here, we present a simple doping-free metal/semiconductor/metal SNPD, which shows strong detection tunability without such a material constraint. The proposed hot-electron SNPD exhibits superior optical and electrical advantages, i.e., optically the coaxial design leads to a strong asymmetrical photoabsorption and results in a high unidirectional photocurrent, as desired by the hot-electron collection; electrically the hot-electrons are generated in the region very close to the barrier, facilitating the electrical transport. Rigorous calculations predict an unbiased photoresponsivity of ∼200 nA/mW.