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Remote sensing technology, which conventionally employs spectrometers to capture hyperspectral images, allowing for the classification and unmixing based on the reflectance spectrum, has been extensively applied in diverse fields, including environmental monitoring, land resource management, and agriculture. However, miniaturization of remote sensing systems remains a challenge due to the complicated and dispersive optical components of spectrometers. Here, m‐phase GaTe0.5Se0.5 with wide‐spectral photoresponses (250–1064 nm) and stack it with WSe2 are utilizes to construct a two‐dimensional van der Waals heterojunction (2D‐vdWH), enabling the design of a gate‐tunable wide‐spectral photodetector. By utilizing the multi‐photoresponses under varying gate voltages, high accuracy recognition can be achieved aided by deep learning algorithms without the original hyperspectral reflectance data. The proof‐of‐concept device, featuring dozens of tunable gate voltages, achieves an average classification accuracy of 87.00% on 6 prevalent hyperspectral datasets, which is competitive with the accuracy of 250–1000 nm hyperspectral data (88.72%) and far superior to the accuracy of non‐tunable photoresponse (71.17%). Artificially designed gate‐tunable wide‐spectral 2D‐vdWHs GaTe0.5Se0.5/WSe2‐based photodetector present a promising pathway for the development of miniaturized and cost‐effective remote sensing classification technology. [ABSTRACT FROM AUTHOR]

The nanopipes in GaN films grown on sapphire substrates using metal-organic chemical vapor deposition were identified as leakage-related defects through investigations by PeakForce tunneling atomic force microscopy. An insertion layer of n-Al0.03Ga0.97N can prevent nanopipes from extending, thereby reducing the leakage current of Schottky diodes. By analyzing the element's distribution in and out of nanopipes on epitaxial wafers, it is inferred that segregation of Ga around nanopipes may be responsible for the leakage. [ABSTRACT FROM AUTHOR]

Facing the future development trend of miniaturization and intelligence of electronic devices, solar‐blind photodetectors based on ultrawide‐bandgap 2D semiconductors have the advantages of low dark current, and high signal‐to‐noise ratio, as well as the features of micro‐nanometer miniaturization and multi‐functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high‐performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO3, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar‐blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV‐C and UV‐A reaches 7.6 × 103. Under 239 nm incident light, the responsivity is 105 mA W−1 and the detectivity is 7.58 × 1012 Jones. Owing to the remarkable anisotropic crystal structure, AsSbO3 also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real‐time imaging function in solar‐blind UV with a convolutional neural network. This study enriches the material system of ultrawide‐bandgap 2D semiconductors and provides insight into the future development of high‐performance solar‐blind UV optoelectronic devices. [ABSTRACT FROM AUTHOR]

Facing the future development trend of miniaturization and intelligence of electronic devices, solar‐blind photodetectors based on ultrawide‐bandgap 2D semiconductors have the advantages of low dark current, and high signal‐to‐noise ratio, as well as the features of micro‐nanometer miniaturization and multi‐functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high‐performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO3, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar‐blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV‐C and UV‐A reaches 7.6 × 103. Under 239 nm incident light, the responsivity is 105 mA W−1 and the detectivity is 7.58 × 1012 Jones. Owing to the remarkable anisotropic crystal structure, AsSbO3 also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real‐time imaging function in solar‐blind UV with a convolutional neural network. This study enriches the material system of ultrawide‐bandgap 2D semiconductors and provides insight into the future development of high‐performance solar‐blind UV optoelectronic devices. [ABSTRACT FROM AUTHOR]

2D organic semiconductor crystals (2D OSCs) are vital for high‐performance electronic and optoelectronic devices owing to their unique material merits. However, it is still challenging to fabricate high‐quality and large‐scale ultrathin 2D OSCs with controllable molecular layers due to the disordered molecular deposition and uncontrollable mass transport in solution‐processing fabrication. Here, a vapor‐induced meniscus modulating strategy for preparing unidirectional and stable Marangoni flow to guide contactless meniscus evolution is reported, which ensures uniform mass transport and ordered molecular deposition to achieve high‐quality ultrathin 2D OSCs. Both the surface tension difference and the substrate wettability are critical to meniscus formation, which results in various meniscus deformation states and film morphologies. Based on the optimized vapor‐solvent system, ultrathin 2D OSCs of C8‐BTBT with precise layer definition are prepared controllably. The discrepancies in liquid film height and solute concentration are decisive in controlling the molecular scale thickness ranging from mono to a few layers. Moreover, the layer‐dependent electronic and optoelectronic properties of the ultrathin films are systematically investigated. Notably, high‐performance polarization‐sensitive solar‐blind photodetectors are achieved with a dichroic ratio of photocurrent up to 2.26, and the corresponding polarimetric image sensor exhibits superior solar‐blind polarization imaging capability thanks to the high crystalline quality. [ABSTRACT FROM AUTHOR]

For low-dimensional materials, the in-plane anisotropy of their structure can realize the detection of polarized light. This characteristic can be utilized to fabricate polarization-sensitive photodetectors without polarizers. It is conductive to the miniaturization and integration of devices. As a typical IV-VI group material, GeSe is easy to be synthesized by chemical vapor transport method, and has obvious response to the light in the visible and near-infrared band. In this study, a GeSe-based polarization-sensitive photodetector was fabricated. The sensitivity of GeSe to the polarization angle of light in the visible and near-infrared bands was explored. And a program was used to perform large-scale imaging. The polarized light response in the visible and near-infrared bands was compared and analyzed by artificial neural network. [ABSTRACT FROM AUTHOR]

Low‐dimensional ultrawide bandgap semiconductors demonstrate great potential in fabricating solar‐blind ultraviolet photodetectors. However, the widespread use of detectors is still limited by the low responsivity, large noise, and dark current, and especially few detectors can fulfill the solar‐blind ultraviolet detection and the polarization dependence simultaneously. Herein, a polarization sensitive solar‐blind ultraviolet photodetector based on ultrathin KNb3O8 nanobelts synthesized via chemical vapor deposition growth, is reported. By selecting suitable substrate and tuning the growth temperature, the nonlayered KNb3O8 crystal is grown into the quasi‐1D ultrathin nanobelt with thickness in the range of 4.8–120 nm. Density functional theory calculations and experimental results indicate that the ultrathin KNb3O8 nanobelt possesses an ultrawide bandgap (4.15 eV) as well as unusual in‐plane structural anisotropy. Benefiting from the above features, the ultrathin KNb3O8 nanobelt‐based device exhibits superior photodetection performances with high responsivity (30 A W−1), high detectivity (5.95 × 1011 Jones), and ultralow dark current (7.1 × 10−15 A) in the solar‐blind ultraviolet region (230–280 nm). In addition, the KNb3O8 photodetector displays strong polarization sensitive photoresponse with a linear dichroic ratio of 1.62 at 254 nm. With these remarkable features, the ultrathin KNb3O8 nanobelt provides great opportunities for designing the next‐generation multifunctional solar‐blind ultraviolet optoelectronic devices. [ABSTRACT FROM AUTHOR]

AbstractDumbbell-shaped carbonate minerals are widely recognized as a distinctive morphology induced by microorganisms. Understanding their morphological evolution and growth mechanisms is essential for elucidating bacterial-mediated carbonate mineralization processes. In this study, we used the mineralizing bacterium Curvibacter sp. strain HJ-1 to induce the formation of dumbbell-shaped carbonate minerals within a rapid crystallization system with a Mg/Ca ratio = 5. A range of microscale analytical techniques, including scanning electron microscopy, focused ion beam, and transmission electron microscopy, were employed to systematically investigate the morphological changes and crystallographic orientation of these minerals. The results reveal that the formation process involves the aggregation of Ca-Mg nanoparticles at both ends of the structure, with bacterial cells acting as a template. These findings offer preliminary insights into the formation mechanisms of dumbbell-shaped minerals and provide a scientific basis for biogenic analysis of field samples. [ABSTRACT FROM AUTHOR]

In an article published in Advanced Functional Materials, researchers Xinghua Wang, Zhongming Wei, Juehan Yang, and their colleagues discuss the development of photodetectors based on AsSbO3 nanosheets. These nanosheets have an ultra-wide bandgap, allowing for highly selective and high-performance detection in the solar-blind ultraviolet band. Additionally, the AsSbO3 nanosheets exhibit linear dichroism and nonlinear optical properties due to their anisotropic crystal structure. This research has implications for machine vision applications. [Extracted from the article]

Solar-blind ultraviolet (UV) detection plays a critical role in imaging and communication due to its low-noise background, high signal-to-noise ratio, and strong anti-interference capabilities. Detecting the polarization state of UV light can enhance image information and expand the communication dimension. Although polarization detection is explored in visible and infrared light, and applied in fields such as astrophysics and submarine seismic wave detection, solar-blind UV polarization detection remains largely unreported. This is primarily due to the challenge of creating UV polarizers with high transmittance, high extinction ratio, and strong resistance to UV radiation. In this study, it is discovered that the space symmetry breaking of the β-Ga 2 O 3 's b-c plane results in a significant optical absorption dichroic ratio. Leveraging β-Ga 2 O 3 's high solar-blind UV response, a lensless solar-blind UV polarization-sensitive photodetector, circumventing the challenges associated with solar-blind UV polarizers is designed. This photodetector exhibits an exceptionally high intrinsic polarization ratio under 254 nm linearly polarized light, approximately two orders of magnitude higher than other reported nanomaterial-based polarization-sensitive photodetectors. Additionally, it demonstrates significant advantages in solar-blind UV imaging and light communication. This work introduces a novel strategy for solar-blind ultraviolet polarization detection and offers a promising approach for solar-blind light communication., (© 2024 Wiley‐VCH GmbH.)

The intentionally designed band alignment of heterostructures and doping engineering are keys to implement device structure design and device performance optimization. According to the theoretical prediction of several typical materials among the transition metal dichalcogenides (TMDs) and group-IV metal chalcogenides, MoS 2 and SnSe 2 present the largest staggered band offset. The large band offset is conducive to the separation of photogenerated carriers, thus MoS 2 /SnSe 2 is a theoretically ideal candidate for fabricating photodetector, which is also verified in the experiment. Furthermore, in order to extend the photoresponse spectrum to solar-blind ultraviolet (SBUV), doping engineering is adopted to form an additional electron state, which provides an extra carrier transition channel. In this work, pure MoS 2 /SnSe 2 and doped MoS 2 /SnSe 2 heterostructures are both fabricated. In terms of the photoelectric performance evaluation, the rejection ratio R 254 /R 532 of the photodetector based on doped MoS 2 /SnSe 2 is five orders of magnitude higher than that of pure MoS 2 /SnSe 2 , while the response time is obviously optimized by 3 orders. The results demonstrate that the combination of band alignment and doping engineering provides a new pathway for constructing SBUV photodetectors., (© 2022 Wiley-VCH GmbH.)