Polarization-sensitive Detection Research Articles

Perovskite quantum dots/WSe2 mixed-dimensional van der Waals heterostructure for photoelectric enhancement and polarization sensitivity

The performance of some heterostructures based devices is limited by strong interlayer coupling and limited electronic structure modulation. Meanwhile, the detection of polarized light holds great significance in future photoelectric fields such as cryptography. In this work, zero-dimensional/two-dimensional (0D/2D) mixed-dimensional van der Waals heterostructure (MvdWH) polarization-sensitive photodetector composed of solution-synthesized CH3NH3PbI3(MAPbI3) perovskite quantum dots (QDs) and chemical vapor deposition (CVD)-grown WSe2 was designed, forming a type II band structure. The MvdWH effectively enhance the carrier transmission rate, and improve the efficiency of charge separation, realizing an ultra-high responsiveness of 217.8 A/W and an ultrasensitive photodetectivity of 2.56 × 1011 Jones under 633 nm illumination. The device shows ultra-fast response times of 4.5/4.9 μs, which is due to the introduction of 0D QDs will shorten the electron transport path and reduces trap-mediated non-radiative recombination. Further, the in-plane anisotropy of MAPbI3 QDs was identified by angle-resolved absorption spectroscopy and angle-resolved polarization Raman spectroscopy, respectively. The MAPbI3/WSe2 device exhibited polarization-sensitive optoelectronic detection with an anisotropy ratio of 1.71, and powerful polarization-sensitive imaging ability, implying that MAPbI3 QDs endows the device with polarization detection and imaging capabilities. These results indicate that the construction of 0D/2D MvdWH opens a new avenue for ultrasensitive and polarization-sensitive photodetection, which depicts opportunities for designing multifunctional, high-performance imaging optoelectronic devices.

Controlled growth of asymmetric chiral TeOx for broad-spectrum, high-responsivity and polarization-sensitive photodetection.

Low-dimensional nanostructures, especially one-dimensional materials, exhibit remarkable anisotropic characteristics due to their low symmetry, making them promising candidates for polarization-sensitive photodetection. Here, we present a chemical vapor deposition synthesis method for tellurium suboxide (TeOx), confirming the practicality of photodetectors constructed from TeOx nanowires (NWs) in high-responsivity, broadband, and polarization-sensitive detection. By precisely controlling the thermodynamics and kinetics of TeOx NWs growth, we achieve large-scale growth of TeOx NWs with highly controllable dimensions and propose a method to induce intrinsic built-in strain in TeOx NWs. Photodetectors based on quasi-one-dimensional TeOx NWs with ohmic contact demonstrate broadband spectral response (638-1550nm), high responsivity (13 700 mA·W-1), and superior air stability. Particularly, owing to the inherent structural anisotropy of the photodetectors, they exhibit polarization-sensitive photodetection, with anisotropy ratios of 1.70 and 1.71 at 638 and 808nm, respectively.

Rolling up 2D WSe2 Nanosheets to 1D Anisotropic Nanoscrolls for Polarization-Sensitive Photodetectors.

The intrinsic low-symmetry crystal structures or external geometries of low-dimensional materials are crucial for polarization-sensitive photodetection. However, these inherently anisotropic materials are limited in variety, and their anisotropy is confined to specific crystal directions. Transforming 2D semiconductors, such as WSe2, from isotropic 2D nanosheets into anisotropic 1D nanoscrolls expands their application in polarization photodetection. Despite this considerable potential, research on polarization photodetection based on nanoscrolls remains scarce. Here, the uniform crystalline orientation of WSe2 nanoscrolls is achieved conveniently and efficiently by applying ethanol droplets to vapor deposition-grown bilayer WSe2 nanosheets. Angle-resolved polarized Raman spectroscopy of WSe2 nanoscrolls demonstrates vibrational anisotropy. Photodetectors based on these nanoscrolls show competitive overall performance with a broadband detection range from 405 to 808nm, a competitive on/off ratio of ≈900, a high detectivity of 3.4×108 Jones, and a fast response speed of ≈30ms. Additionally, WSe2 nanoscroll-based photodetectors exhibit strong polarization-sensitive detection with a maximum dichroic ratio of 1.5. More interestingly, due to high photosensitivity, the WSe2 nanoscroll detectors can easily record sequential puppy images. This work reveals the potential of WSe2 nanoscrolls as excellent polarization-sensitive photodetectors and provides new insights into the development of high-performance optoelectronic devices.

Directional Phase and Polarization Manipulation Using Janus Metasurfaces.

Janus metasurfaces, exemplifying two-faced 2D metamaterials, have shown unprecedented capabilities in asymmetrically manipulating the wavefront of electromagnetic waves in both forward and backward propagating directions, enabling novel applications in asymmetric information processing, security, and signal multiplexing. However, current Janus metasurfaces only allow for directional phase manipulation, hindering their broader application potential. Here, the study proposes a versatile Janus metasurface platform that can directionally control the phase and polarization of terahertz waves by integrating functionalities of half-wave plates, quarter-wave plates, and metallic gratings within a cascaded metasurface structure. As a proof-of-principle, the study experimentally demonstrates Janus metasurfaces capable of independent and simultaneous control over phase and polarization, showcasing propagation direction-encoded focusing and polarization conversion. Moreover, the directionally focused points are utilized with distinct polarization states for advanced applications in direction- and polarization-sensitive detection and imaging. This unique strategy for simultaneous phase and polarization control with direction-dependent versatility opens new avenues for designing ultra-compact devices with significant implications in imaging, encryption, and data storage.

Atomic-Thin WS2 Kirigami for Bidirectional Polarization Detection.

The assembly and patterning engineering in two-dimensional (2D) materials hold importance for chip-level designs incorporating multifunctional detectors. At present, the patterning and stacking methods of 2D materials inevitably introduce impurity instability and functional limitations. Here, the space-confined chemical vapor deposition method is employed to achieve state-of-the-art kirigami structures of self-assembled WS2, featuring various layer combinations and stacking configurations. With this technique as a foundation, the WS2 nano-kirigami is integrated with metasurface design, achieving a photodetector with bidirectional polarization-sensitive detection capability in the infrared spectrum. Nano-kirigami can eliminate some of the uncontrollable factors in the processing of 2D material devices, providing a freely designed platform for chip-level multifunctional detection across multiple modules.

Permittivity tensor imaging: modular label-free imaging of 3D dry mass and 3D orientation at high resolution

The dry mass and the orientation of biomolecules can be imaged without a label by measuring their permittivity tensor (PT), which describes how biomolecules affect the phase and polarization of light. Three-dimensional (3D) imaging of PT has been challenging. We present a label-free computational microscopy technique, PT imaging (PTI), for the 3D measurement of PT. PTI encodes the invisible PT into images using oblique illumination, polarization-sensitive detection and volumetric sampling. PT is decoded from the data with a vectorial imaging model and a multi-channel inverse algorithm, assuming uniaxial symmetry in each voxel. We demonstrate high-resolution imaging of PT of isotropic beads, anisotropic glass targets, mouse brain tissue, infected cells and histology slides. PTI outperforms previous label-free imaging techniques such as vector tomography, ptychography and light-field imaging in resolving the 3D orientation and symmetry of organelles, cells and tissue. We provide open-source software and modular hardware to enable the adoption of the method.

Self-Rolled-Up WSe2 One-Dimensional/Two-Dimensional Homojunctions: Enabling High-Performance Self-Powered Polarization-Sensitive Photodetectors.

Mixed-dimensional heterostructures integrate materials of diverse dimensions with unique electronic functionalities, providing a new platform for research in electron transport and optoelectronic detection. Here, we report a novel covalently bonded one-dimensional/two-dimensional (1D/2D) homojunction structure with robust junction contacts, which exhibits wide-spectrum (from the visible to near-infrared regions), self-driven photodetection, and polarization-sensitive photodetection capabilities. Benefiting from the ultralow dark current at zero bias voltage, the on/off ratio and detectivity of the device reach 1.5 × 103 and 3.24 × 109 Jones, respectively. Furthermore, the pronounced anisotropy of the WSe2 1D/2D homojunction is attributed to its low symmetry, enabling polarization-sensitive detection. In the absence of any external bias voltage, the device exhibits strong linear dichroism for wavelengths of 638 and 808 nm, with anisotropy ratios of 2.06 and 1.96, respectively. These results indicate that such mixed-dimensional structures can serve as attractive building blocks for novel optoelectronic detectors.

Nanoskiving of van der Waals Materials toward Edge/Basal Plane Contact Heterojunctions for High-Performance Photodetection.

The unique features of edges in van der Waals materials may lead to edge-basal plane contacts that could provide new opportunities for electronic and optoelectronic devices. However, few studies have addressed edge/basal plane contact heterojunctions owing to the formidable challenges in integrating edges with the basal plane to form a heterojunction. Here, taking the example of black phosphorus (BP)/ReS2, a heterojunction with contact between the edge and the basal plane was successfully achieved by the introduction of a nanoskiving technique to fabricate BP edges with controlled orientation, followed by the dry transfer of a ReS2 flake. The deformation of BP during the nanoskiving process was clearly revealed, where interlayer slipping in the BP determined the formation of the edges. The edge/basal plane contact heterojunctions based on BP/ReS2 exhibited a reverse-rectifying behavior upon contact, and a high rectifying current was attributed to direct tunneling and Fowler-Nordheim tunneling in low and high bias regimes, respectively. As a photodetector, the heterojunction diode demonstrated an impressive responsivity of 65 A/W, a rapid response time (<10 ms), and polarization-sensitive detection under 532 nm illumination without gate biasing.

Anisotropic Te/PdSe2 Van Der Waals Heterojunction for Self-Powered Broadband and Polarization-Sensitive Photodetection.

Polarization-sensitive broadband optoelectronic detection is crucial for future sensing, imaging, and communication technologies. Narrow bandgap 2D materials, such as Te and PdSe2, show promise for these applications, yet their polarization performance is limited by inherent structural anisotropies. In this work, a self-powered, broadband photodetector utilizing a Te/PdSe2 van der Waals (vdWs) heterojunction, with orientations meticulously tailored is introduced through polarized Raman optical spectra and tensor calculations to enhance linear polarization sensitivity. The device exhibits anisotropy ratios of 1.48 at 405nm, 3.56 at 1550nm, and 1.62 at 4µm, surpassing previously-reported photodetectors based on pristine Te and PdSe2. Additionally, it exhibits high responsivity (617mAW-1 at 1550nm), specific detectivity (5.27×1010Jones), fast response (≈4.5µs), and an extended spectral range beyond 4µm. The findings highlight the significance of orientation-engineered heterostructures in enhancing polarization-sensitive photodetectors and advancing optoelectronic technology.

Highly Sensitive Broadband Polarized Photodetector Based on the As0.6P0.4/WSe2 Heterostructure toward Imaging and Optical Communication Application.

Polarization-sensitive photodetectors based on two-dimensional anisotropic materials still encounter the issues of narrow spectral coverage and low polarization sensitivity. To address these obstacles, anisotropic As0.6P0.4 with a narrow band gap has been integrated with WSe2 to construct a type-II heterostructure, realizing a high-performance polarization-sensitive photodetector with broad spectral range from 405 to 2200 nm. By operating in photovoltaic mode at zero bias, the device shows a very low dark current of ∼0.02 picoampere, high responsivity of 492 m A/W, and high photoswitching ratio of 6 × 104, yielding a high specific detectivity of 1.4 × 1012 Jones. The strong in-plane anisotropy of As0.6P0.4 endows the device with a capability of polarization-sensitive detection with a high polarization ratio of 6.85 under a bias voltage. As an image sensor and signal receiver, the device shows great potential in imaging and optical communication applications. This work develops an anisotropic vdW heterojunction to realize polarization-sensitive photodetectors with wide spectral coverage, fast response, and high sensitivity, providing a new candidate for potential applications of polarization-resolved electronics and photonics.

Asymmetrical Cross-Polarization Coupling in a Whispering-Gallery Microresonator

Cross-polarization coupling between transverse electric (TE) and transverse magnetic (TM) whispering-gallery modes in an optical microresonator produces effects such as coupled-mode induced transparency (CMIT). The detailed analytical theory of this coupling indicates that the TE-to-TM and TM-to-TE couplings may have different strengths. Using an experimental setup centered around a hollow bottle resonator and polarization-sensitive throughput detection, that had been used in previous CMIT experiments, this asymmetry was confirmed and studied. By fitting the throughput spectra of both polarizations to the numerical output of a basic model, the asymmetry parameter defined as the ratio of the coupling amplitudes was determined from the output power in the polarization orthogonal to that of the input. The results of many experiments give a range for this ratio, roughly from 0.2 to 4, that agrees with the range predicted by the detailed theory. An analytical approximation of this ratio shows that the main reason for the asymmetry is a difference in the axial orders of the coupled modes. In some experimental cases, the orthogonal output is not well fitted by the model that assumes a single mode of each polarization, and we demonstrate that this fitting discrepancy can be the result of additional mode interactions.

Synergistic-potential engineering enables high-efficiency graphene photodetectors for near- to mid-infrared light

High quantum efficiency and wide-band detection capability are the major thrusts of infrared sensing technology. However, bulk materials with high efficiency have consistently encountered challenges in integration and operational complexity. Meanwhile, two-dimensional (2D) semimetal materials with unique zero-bandgap structures are constrained by the bottleneck of intrinsic quantum efficiency. Here, we report a near-mid infrared ultra-miniaturized graphene photodetector with configurable 2D potential well. The 2D potential well constructed by dielectric structures can spatially (laterally and vertically) produce a strong trapping force on the photogenerated carriers in graphene and inhibit their recombination, thereby improving the external quantum efficiency (EQE) and photogain of the device with wavelength-immunity, which enable a high responsivity of 0.2 A/W–38 A/W across a broad infrared detection band from 1.55 to 11 µm. Thereafter, a room-temperature detectivity approaching 1 × 109 cm Hz1/2 W−1 is obtained under blackbody radiation. Furthermore, a synergistic effect of electric and light field in the 2D potential well enables high-efficiency polarization-sensitive detection at tunable wavelengths. Our strategy opens up alternative possibilities for easy fabrication, high-performance and multifunctional infrared photodetectors.

Self-powered polarization-sensitive photodetection and imaging based on Sb[formula omitted]Se[formula omitted] microbelt/Si van der Waals heterojunction with MXene transmittance window

Polarization-sensitive detection and imaging have many significant applications in target recognition, optical switches, industrial inspection, and so on. Herein, on-chip near-infrared photodetectors based on individual Sb2Se3 microbelt/Si van der Waals heterojunction with MXene transmittance window were designed. The fabricated Sb2Se3 microbelt/Si photodetector displays a broad spectral response that spans the visible to near-infrared light regions, as well as a peak photoresponse at a wavelength of 1000 nm. The optimized Sb2Se3 microbelt/Si photodetector exhibits excellent photovoltaic performance with an ultralow dark current of 10 pA, a high responsivity of 25 mA/W, a favorable detectivity of 1010 Jones, a fast response time of 1.7 ms/2.9 ms under near-infrared illumination with power density of 0.1 mW/cm2. The identified performance can be attributed to the heterojunction’s type-II band configuration, making it suited for the quick separation of photo-generated carriers. More importantly, polarization-sensitive photodetectors with an anisotropy ratio of 1.21 to 1.28 under the illumination of 940 nm light can be achieved. The Sb2Se3 microbelt/Si photodetector also demonstrates high-resolution single-pixel polarimetric imaging at zero bias. This work demonstrates an effective strategy for using anisotropic/isotropic Sb2Se3 microbelt/Si van der Waals heterojunction to realize high-performance, self-powered, and polarization-sensitive detection and imaging.

Pioneering Two-Dimensional Perovskites Featuring Four-Layer Organic Spacers for Polarization-Sensitive Photodetection.

Hybrid perovskites have great potential in photovoltaics and photodetection. Specially, two-dimensional (2D) hybrid perovskites have been discovered to show distinctive applications in polarization-sensitive photodetection due to their intrinsic anisotropy. Herein, we designed a new type of 2D perovskite by introducing bifunctional alkylammonium as an organic spacer, (β-Ala)4PbBr4 (1, where β-Ala+ is 3-aminopropanoic), which has four organic spacers in adjacent inorganic layers and adjacent organic layers are linked by hydrogen bonding. The pioneering structure with four organic spacers enables an intrinsic high strong anisotropy, facilitating polarization-sensitive detection. The analysis of the crystal structure and optical properties further elucidates the natural anisotropic properties of 1. Strikingly, 1 has a strong optical dichroism (αc/αb ≈ 7.4 in 405 nm), and the polarization-sensitive detector on single crystals of 1 exhibits a large polarization ratio (Imax/Imin ≈ 2.0). This result highlights that the employment of bifunctional cations is efficient to explore new type 2D perovskites for potentially high-performance polarization-sensitive detection.

One-step rolling fabrication of VO2 tubular bolometers with polarization-sensitive and omnidirectional detection.

Uncooled infrared detection based on vanadium dioxide (VO2) radiometer is highly demanded in temperature monitoring and security protection. The key to its breakthrough is to fabricate bolometer arrays with great absorbance and excellent thermal insulation using a straightforward procedure. Here, we show a tubular bolometer by one-step rolling VO2 nanomembranes with enhanced infrared detection. The tubular geometry enhances the thermal insulation, light absorption, and temperature sensitivity of freestanding VO2 nanomembranes. This tubular VO2 bolometer exhibits a detectivity of ~2 × 108 cm Hz1/2 W-1 in the ultrabroad infrared spectrum, a response time of ~2.0 ms, and a calculated noise-equivalent temperature difference of 64.5 mK. Furthermore, our device presents a workable structural paradigm for polarization-sensitive and omnidirectional light coupling bolometers. The demonstrated overall characteristics suggest that tubular bolometers have the potential to narrow performance and cost gap between photon detectors and thermal detectors with low cost and broad applications.

Polarization-sensitive UV detector based on a double-layer subwavelength grating of Al and ZnO

Polarization-sensitive detectors are of great importance in the fields of remote sensing and imaging, environmental monitoring, and medical diagnosis. The surface plasmon effect can the enable polarization sensitivity of photodetectors through metallic gratings. However, limited by the precision of the nano-fabrication process, it is difficult to fabricate an ultraviolet (UV) polarization-sensitive detector integrated with sub-wavelength metal gratings and the polarization extinction ratio is relatively low. In this paper, an Al–ZnO composite double-layer grating structure was designed. The ZnO active layer and the Al layer were both fabricated into same-sized grating structures. Through this design, the slit width could be enlarged to some degree, while the response to 90° polarized light remained low. It is beneficial to realize a high polarization ratio and to spare the need for rigid fabrication accuracy. In addition, the influence of the structural parameters of the grating on the performance of the detector was studied by simulation. It was found that the resonance wavelength can be adjusted by changing the slit width and grating height, respectively. This provides a useful means for polarization-sensitive detection in different wavelength ranges. The polarization extinction ratio of the detector with a double-layer composite grating can reach 52 in the UV band (365 nm). This provides a good alternative to replace the traditional framework relying on the combination of polarizers and detectors. Moreover, it is a promising structure for high-density integrated photodetectors and imaging chips in the future.

Highly in-plane anisotropic 2D ReSe2 for polarization-sensitive photodetectors

Here we report a new member of in-plane anisotropic 2D materials Rhenium Diselenide (ReSe2) which holds a stable distorted 1 T’ phase with its relatively narrow bandgap to explore the in-plane anisotropic structural, electrical, and optical properties. The proposed polarization-sensitive photodetectors based on few-layer ReSe2 provides highly anisotropic photodetection behavior with linearly dichroic ratio up to ≈2.62 under 808 nm illumination. We measured carrier transport in space and time by mapping carrier density in a ReSe2 plate using transient absorption microscopy. These results directly determined the carrier diffusion coefficients of about 4100 cm2 s-1 and 2900 cm2 s-1 along the armchair and zigzag directions, respectively, providing fundamental parameters to better understand the anisotropy of ReSe2 and promote future 2D optoelectronic applications in polarization-sensitive detection.

High-Performance Photodetectors With Polarization Sensitivity Based on p-n and p-p+ Black Phosphorus/Germanium Heterojunctions

The heterostructures between atomically thin 2-D and 3-D semiconductors show great potential for high-performance photodetector. In this work, the efficient light detection of the p-n and p-p+ black phosphorus (bP)/germanium (Ge) heterojunction photodiode has been demonstrated. With the change of Ge doping type, the rectification direction of the heterojunction diode formed by bP and Ge could be reversed. Due to the enhanced photocarrier separation at the reverse bias, the bP/n-Ge (bP/p-Ge) device has a responsivity of 6.08 (3.43) A/W under 1550-nm illumination, with fast response speed in the 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> level. The bP/n-Ge device has a significant photovoltaic effect due to the small conduction band energy offset, with a large open-circuit voltage of 0.34 V. Under the illumination of light with different polarization directions, the device exhibits apparent polarization-sensitive detection, and the dichroic ratio of bP/n-Ge and bP/p-Ge devices is 4.25 and 3.85, respectively. These results suggest that the bP/Ge heterojunction photodetector would have great potential in high-performance, self-powered, and polarization-sensitive photodetection.

Strong Anisotropic Two-Dimensional In2Se3 for Light Intensity and Polarization Dual-Mode High-Performance Detection

Detecting the light from different freedom is of great significance to gain more information. Two-dimensional (2D) materials with low intrinsic carrier concentration and highly tunable electronic structure have been considered as the promising candidate for future room-temperature multi-functional photodetectors. However, current investigations mainly focus on intensity-sensitive detection; the multi-dimensional photodetection such as polarization-sensitive photodetection is still in its early stage. Herein, the intensity- and polarization-sensitive photodetection based on α-In2Se3 is studied. By using angle-resolved polarized Raman spectroscopy, it is demonstrated that α-In2Se3 shows an anisotropic phonon vibration property indicating its asymmetric structure. The α-In2Se3-based photodetector has a photoelectric performance with a responsivity of 1936 A/W and a specific detectivity of 2.1 × 1013 Jones under 0.2 mW/cm2 power density at 400 nm. Moreover, by studying the polarized angle-resolved photoelectrical effect, it is found that the ratio of maximum and minimum photocurrent (dichroic ratio) reaches 1.47 at 650 nm suggesting good polarization-sensitive detection. After post-annealing, α-In2Se3 in situ converts to β-In2Se3 which has similar in-plane anisotropic crystallinity and exhibits a dichroic ratio of 1.41. It is found that the responsivity of β-In2Se3 is 6 A/W, much lower than that of α-In2Se3. The high-performance light intensity- and polarization-detection of α-In2Se3 enlarges the 2D anisotropic materials family and provides new opportunities for future dual-mode photodetection.

Polar 2D hybrid perovskite crystals with intrinsic strong linear dichroism for polarization-sensitive and self-powered detection

By incorporating a brominated aromatic cation as an interlayered spacer, we have prepared a 2D polar hybrid perovskite for polarization-sensitive and self-powered photodetection.