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Advances in III-V semiconductor infrared absorbers and detectors
摘要： Advances in bulk III-V semiconductor material such as InGaAsSb and metamorphic InAsSb, as well as in a variety of type-II superlattices such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short to the very long wavelength infrared. We perform basic theoretical analysis to provide comparisons of different infrared materials. We also briefly report experimental results on a mid-wavelength InAs/InAsSb type-II superlattice unipolar barrier infrared detector and a focal plane array with significantly higher operating temperature than InSb.
关键词： unipolar barrier,MWIR,infrared detector,e-SWIR,LWIR,antimonide,type-II superlattice,nBn,effective mass
更新于2025-09-23 15:23:52
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Diffuse Reflectance Spectroscopy (Vis-Nir-Swir) as a Promising Tool for Blue Carbon Quantification in Mangrove Soils: A Case of Study in Tropical Semiarid Climatic Conditions
摘要： The assessment of the soil organic carbon (SOC) stocks in mangrove ecosystems is essential for coastal management activities seeking the mitigation of CO2 emissions. However, the wet chemical analysis conventionally used to quantify SOC may overestimate SOC content due to oxidation of reduced compounds. This work focused on the use of diffuse reflectance spectroscopy (DRS) for predicting SOC in mangrove forest areas. When used properly, DRS may be, in some cases, a more accurate and more efficient method for the determination of SOC in mangrove soils than conventional analytical approaches. Furthermore, variable selection may simplify and improve prediction accuracy, reducing collinearity in the dataset used and allowing better SOC quantification through more interpretable and robust models.
关键词： Tropical semiarid climatic conditions,Mangrove soils,Vis-NIR-SWIR,Blue Carbon,Diffuse reflectance spectroscopy
更新于2025-09-23 15:21:01
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The role of CdS doping in improving SWIR photovoltaic and photoconductive responses in solution grown CdS/PbS heterojunctions
摘要： Low cost Short Wavelength Infrared (SWIR) photovoltaic (PV) detectors and solar cells are of very great interest, yet the main production technology today is based on costly epitaxial growth of InGaAs layers. In this study, layers of p-type, quantum confined (QC) PbS nano-domains (NDs) structure that were engineered to absorb SWIR light at 1550nm (Eg=0.8 eV) were fabricated from solution using the Chemical Bath Deposition (CBD) technique. The layers were grown on top of two different n-type CdS intermediate layers (Eg=2.4 eV) using two different CBD protocols on Fluoride Tin Oxide (FTO) substrates. Two types of CdS/PbS heterojunction were obtained to serve as SWIR PV detectors. The two resulting devices showed similar photoluminescence behavior, but a profoundly different electrical response to SWIR illumination. One type of CdS/PbS heterojunction exhibited a PV response to SWIR light, while the other demonstrated a photo-response to SWIR light only under an applied bias. To clarify this intriguing phenomenon, and since the only difference between the two heterojunctions could be the doping level of the CdS layer, we measured the doping level of this layer by means of the surface photo voltage (SPV). This yielded different polarizations for the two devices, indicating different doping levels of the CdS for the two different fabrication protocols, which was also confirmed by Hall Effect measurements. We performed current voltage measurements under super bandgap illumination, with respect to CdS, and got an electrical response indicating a barrier free for holes transfer from the CdS to the PbS. The results indicate that the different response does, indeed, originate from variations in the band structures at the interface of the CdS/PbS heterojunction due to the different doping levels of the CdS. We found that, unlike solar cells or visible light detectors having similar structure, in SWIR photodetectors, a type I heterojunction is formed having a barrier at the interface that limits the injection of the photo-exited electrons from the QC-PbS to the CdS side. Higher n-doped CdS generates a narrow depletion region on the CdS side, with a spike like barrier that is narrow enough to enable tunneling current, leading to a PV current. Our results show that an external quantum efficiency (EQE) of ~2% and an internal quantum efficiency (IQE) of ~20% can be obtained, at zero bias, for CBD grown SWIR sensitive CdS/PbS-NDs heterojunctions.
关键词： CBD,CdS/PbS heterojunction,SWIR photodetector,PbS NDs
更新于2025-09-23 15:19:57
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Orthogonal Shortwave Infrared Emission Based on Rare Earth Nanoparticles for Interference-free Logical Code and Bio-imaging
摘要： Shortwave infrared (SWIR) photoluminescence has received intense interest in many fields in the recent years thanks to the advantages of its wide wavelength, high tissue imaging ability and it is invisible to the naked eye. However, achieving orthogonal SWIR emission still remains challenge. In the present study, synthesized NaErF4@NaLuF4 (Er@Lu) and NaYF4:Nd@NaLuF4 (Y:Nd@Lu) nanoparticles emitted atom-liked SWIR emission, respectively, and the separated distance between the SWIR emission was beyond 50 nm, which permitted orthogonal SWIR signal acquirement with optical filters. Furthermore, we designed an invisible logical code by manipulating the orthogonal SWIR emission of the lanthanide fluoride nanoparticles, which was further operated by basic logical operations and applied in information encryption and anti-counterfeit. In addition, the emission between these two hydrophilic nanoparticles could be also separated in vivo without signals interference and the orthogonal SWIR imaging mode was achieved, which was demonstrated in bio-imaging experiment in vivo. This demonstration extended the orthogonal SWIR emission capacity by controlling the orthogonal emission, opening new opportunities in the data security, diseases diagnosis and non-interference label in vivo.
关键词： bio-imaging,anti-counterfeit,Orthogonal shortwave infrared,SWIR logical codes,lanthanide fluoride nanoparticles
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 9th International Nanoelectronics Conferences (INEC) - Kuching, Malaysia (2019.7.3-2019.7.5)] 2019 IEEE 9th International Nanoelectronics Conferences (INEC) - Low-cost SWIR Silicon-based Graphene Oxide Photodetector
摘要： Conventional silicon (Si) semiconductor with the integration of grapheme oxide (GO) provide new procedure for enhancing the performance of the broadband photodiode device. A proposed GO photodetector (PD) was prepared using drop-cast method for infrared (IR) detection. Photodetection was performed under 1480 nm laser illumination for powers ranging from 8.16 to 61.64 mW. We demonstrate a stable and reproducible plasmonic enchanced GO on Si substrate which has a responsivity of 0.82 mA/W. The enhancement of the GO on Si PD is 141 times higher than the bare p-Si PD. Various direct current (DC) bias voltages were used to vary the sensitivity of the device. Higher modulation frequency of 500 Hz showed a rise time and fall time of around 228 μs and 250 μs respectively. These performance parameters indicate that the PD has the ability to detect in IR region which is suitable to be used in optoelectronic devices especially in optical telecommunications.
关键词： SWIR,Silicon-based,Graphene Oxide,Photodetector
更新于2025-09-16 10:30:52
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Directed self-assembly of viologen-based 2D semiconductors with intrinsic UVa??SWIR photoresponse after photo/thermo activation
摘要： Extending photoresponse ranges of semiconductors to the entire ultraviolet–visible (UV)–shortwave near-infrared (SWIR) region (ca. 200–3000 nm) is highly desirable to reduce complexity and cost of photodetectors or to promote power conversion efficiency of solar cells. The observed up limit of photoresponse for organic-based semiconductors is about 1800 nm, far from covering the UV–SWIR region. Here we develop a cyanide-bridged layer-directed intercalation approach and obtain a series of two viologen-based 2D semiconductors with multispectral photoresponse. redox-active N-methyl bipyridinium cations with near-planar structures are sandwiched by cyanide-bridged MnII–FeIII or ZnII–FeIII layers. Radical–π interactions among the infinitely π-stacked N-methyl bipyridinium components favor the extension of absorption range. Both semiconductors show light/thermo-induced color change with the formation of stable radicals. They have intrinsic photocurrent response in the range of at least 355–2400 nm, which exceeds all reported values for known single-component organic-based semiconductors.
关键词： photoresponse,viologen-based,semiconductors,UV–SWIR,2D materials
更新于2025-09-16 10:30:52
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InAs on GaAs Photodetectors Using Thin InAlAs Graded Buffers and Their Application to Exceeding Short-Wave Infrared Imaging at 300?K
摘要： Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1–3 μm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 μm. This study presents an InAs p-i-n photodetector grown on a GaAs substrate (001) by inserting 730-nm thick inxAl1?xAs graded and AlAs buffer layers between the InAs layer and the GaAs substrate. At room temperature, the fabricated InAs photodetector operated in an infrared range of approximately 1.5–4 μm and its detectivity (D*) was 1.65 × 108 cm · Hz1/2 · W?1 at 3.3 μm. To demonstrate performance, the Sherlock Holmes mapping images were obtained using the photodetector at room temperature.
关键词： InxAl1?xAs graded buffer,InAs p-i-n photodetector,GaAs substrate,room temperature operation,Short-wave infrared (SWIR),InGaAs photodetectors
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Cancun (2018.8.29-2018.8.31)] 2018 IEEE 15th International Conference on Group IV Photonics (GFP) - Ge<inf>0.9</inf>Sn<inf>0.1</inf> p-i-n Photodiode with Record-High Responsivity at Two-Micron-Wavelength
摘要： We demonstrate a Ge0.9Sn0.1 photodiode on Si substrate with record-high responsivity Rop of 0.17 A/W at wavelength λ of 2 μm. Fourier-transform infrared spectroscopy (FTIR) reveals that the detector has a cutoff wavelength λc at ~2.6 μm.
关键词： SWIR,CVD,photodiode,GeSn
更新于2025-09-11 14:15:04
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Snow Cover Monitoring with Chinese Gaofen-4 PMS Imagery and the Restored Snow Index (RSI) Method: Case Studies
摘要： Snow cover is an essential climate variable of the Global Climate Observing System. Gaofen-4 (GF-4) is the first Chinese geostationary satellite to obtain optical imagery with high spatial and temporal resolution, which presents unique advantages in snow cover monitoring. However, the panchromatic and multispectral sensor (PMS) onboard GF-4 lacks the shortwave infrared (SWIR) band, which is crucial for snow cover detection. To reach the potential of GF-4 PMS in snow cover monitoring, this study developed a novel method termed the restored snow index (RSI). The SWIR reflectance of snow cover is restored firstly, and then the RSI is calculated with the restored reflectance. The distribution of snow cover can be mapped with a threshold, which should be adjusted according to actual situations. The RSI was validated using two pairs of GF-4 PMS and Landsat-8 Operational Land Imager images. The validation results show that the RSI can effectively map the distribution of snow cover in these cases, and all of the classification accuracies are above 95%. Signal saturation slightly affects PMS images, but cloud contamination is an important limiting factor. Therefore, we propose that the RSI is an efficient method for monitoring snow cover from GF-4 PMS imagery without requiring the SWIR reflectance.
关键词： GF-4,PMS,restored snow index,snow cover,SWIR
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A Hyperspectral LiDAR with Eight Channels Covering from VIS to SWIR
摘要： Hyperspectral LiDAR (HSL) possesses the advantages of the LiDAR and the hyperspectral detection, and detects ranging and spectrum information synchronously, by one HSL system. The data fusion is also avoided. At present, the spectrum range of reported HSLs usually covers only 500 nm-1000 nm (from visual (VIS) to near infrared (NIR) band). However, there is requirement to extend the spectrum range to short wave infrared (SWIR) band, which often contains more useful spectral information. In this paper, a HSL covering the spectrum from VIS to SWIR is reported. In the HSL, the echoes are divided into two sections and are detected by the different optoelectronic devices, of which the spectral response ranges are respectively compatible to the corresponding echoes. The HSL detection experiment in the laboratory was carried out. The waveforms of the echoes were analyzed, and the spectra of different targets were measured by the HSL. The experiment results demonstrate the capability of the prototyped HSL that obtaining the ranging information and the spectrum information of the targets in VIS-SWIR bands synchronously.
关键词： remote sensing,SWIR,supercontinuum laser,hyperspectral LiDAR
更新于2025-09-09 09:28:46