Near-infrared Detector Research Articles

PdSe2/2H-MoTe2 Heterojunction Self-Powered Photodetector: Broadband Photodetection and Linear/Circular Polarization Capability.

In this research, we introduce a PdSe2/2H-MoTe2 heterojunction photodetector that exhibits both broadband self-powered photodetection and linear/circular polarization detection capabilities. It has a broad spectral response range (covering 375-2200 nm) and reaches a peak sensitivity at 532 nm, exhibiting a notable responsivity of 7.3 × 103 A/W and a substantial specific detectivity of 8.5 × 1012 Jones. Even in the near-infrared region of 1310 nm, it still has a high responsivity of 20 A/W. The self-powered photodetection capabilities of the PdSe2/2H-MoTe2 heterojunction are equally impressive, covering a broad range from 375 to 1550 nm, with a responsivity of 243 mA/W, a specific detectivity of 6.46 × 1010 Jones, a fill factor of 0.8, and an external quantum efficiency of 56.73%. Finally, simultaneous implementation of linear/circular polarization detection on the PdSe2/2H-MoTe2 heterojunction provides a powerful solution for near-infrared full-Stokes polarization detectors with high integration, miniaturization, and portability.

Growth and Characterization of AgBiS2 Bulk Single Crystals for Near-Infrared Detectors

Growth and Characterization of AgBiS₂ Bulk Single Crystals for Near-Infrared Detectors

A simple model of dust extinction in gamma-ray burst host galaxies

Context. Gamma-ray burst (GRB) afterglows are powerful probes for studying the different properties of their host galaxies (e.g., the interstellar dust) at all redshifts. By fitting their spectral energy distribution (SED) over a large range of wavelengths, we can gain direct insights into the properties of the interstellar dust by studying the extinction curves. Unlike the dust extinction templates, such as those of the average Milky Way (MW) or the Small and Large Magellanic Cloud (SMC and LMC), the extinction curves of galaxies outside the Local Group exhibit deviation from these laws. Altogether, X-ray and gamma-ray satellites as well as ground-based telescopes, such as Neil Gehrels Swift Observatory (Swift) and Gamma-Ray Optical and Near-Infrared Detector (GROND), provide measurements of the afterglows from the X-ray to the NIR, which can be used to extract information on dust extinction curves along their lines of sight (LoS). The study presented in this paper undertakes such a photometric study, comprising a preparatory work for the SVOM mission and its ground-based follow-up telescope COLIBRI. Aims. We propose a simple approach to parameterize the dust extinction curve of GRB host galaxies. The model used in this analysis is based on a power law form with the addition of a Loretzian-like Drude profile with two parameters: the extinction slope, γ, and the 2175 Å bump amplitude, Eb. Methods. Using the g′r′i′z′JHKs GROND filter bands, we tested our dust extinction model and explored the parameter space in extinction and redshift by fitting SEDs of simplified simulations of GRB afterglow spectra based on different extinction curve templates. From a final sample of 10 real Swift/GROND extinguished GRBs, we determined the quantities of the dust extinction in their host and measured their extinction curves. Results. We find that our derived extinction curves are in agreement with the spectroscopic measurements reported for four GRBs in the literature. We compared four other GRBs to the results of photometric studies where fixed laws were used to fit their data. We additionally derived two new GRB extinction curves. The measured average extinction curve is given by a slope of γ = 1.051 ± 0.129 and Eb = 0.070 ± 0.036, which is equivalent to a quasi-featureless in-between SMC-LMC template. This is consistent with previous studies aimed at deriving the dust host galaxy extinction where we expect that small dust grains dominate in GRB environment, yielding a steeper curve than the mean MW extinction curve.

Ultrafast near-infrared pyroelectric detector based on inhomogeneous plasmonic metasurface

Pyroelectric (PE) detection technologies have attracted extensive attention due to the cooling-free, bias-free, and broadband properties. However, the PE signals are generated by the continuous energy conversion processes from light, heat, to electricity, normally leading to very slow response speeds. Herein, we design and fabricate a PE detector which shows extremely fast response in near-infrared (NIR) band by combining with the inhomogeneous plasmonic metasurface. The plasmonic effect dramatically accelerates the light-heat conversion process, unprecedentedly improving the NIR response speed by 2−4 orders of magnitude to 22 μs, faster than any reported infrared (IR) PE detector. We also innovatively introduce the concept of time resolution into the field of PE detection, which represents the detector’s ability to distinguish multiple fast-moving targets. Furthermore, the spatially inhomogeneous design overcomes the traditional narrowband constraint of plasmonic systems and thus ensures a wideband response from visible to NIR. This study provides a promising approach to develop next-generation IR PE detectors with ultrafast and broadband responses.

Perovskite versus Standard Photodetectors.

Perovskites have been largely implemented into optoelectronics as they provide several advantages such as long carrier diffusion length, high absorption coefficient, high carrier mobility, shallow defect levels and finally, high crystal quality. The brisk technological development of perovskite devices is connected to their relative simplicity, high-efficiency processing and low production cost. Significant improvement has been made in the detection performance and the photodetectors' design, especially operating in the visible (VIS) and near-infrared (NIR) regions. This paper attempts to determine the importance of those devices in the broad group of standard VIS and NIR detectors. The paper evaluates the most important parameters of perovskite detectors, including current responsivity (R), detectivity (D*) and response time (τ), compared to the standard photodiodes (PDs) available on the commercial market. The conclusions presented in this work are based on an analysis of the reported data in the vast pieces of literature. A large discrepancy is observed in the demonstrated R and D*, which may be due to two reasons: immature device technology and erroneous D* estimates. The published performance at room temperature is even higher than that reported for typical detectors. The utmost D* for perovskite detectors is three to four orders of magnitude higher than commercially available VIS PDs. Some papers report a D* close to the physical limit defined by signal fluctuations and background radiation. However, it is likely that this performance is overestimated. Finally, the paper concludes with an attempt to determine the progress of perovskite optoelectronic devices in the future.

Engineering optoelectronic properties of [formula omitted] superlattices using first principles method

Recent advancements in thin-film growth techniques have opened doors for engineering innovative heterostructures with ultra-thin layers. These artificial superlattices hold promise for novel optoelectronic devices. However, a complete understanding of their properties is crucial for optimal design. In this study, we employ the full-potential linearized augmented plane wave (FP−LAPW) approach based on density functional theory (DFT) to engineer the optoelectronic properties of (HgSe)n/(ZnTe)n superlattices by controlling the number of layers (n) in SLs; The exchange-correlation potential was calculated by the generalized gradient GGA approximation and the optoelectronics properties has adjusted by the Tran-Blaha modified Becke-Johnson (TB−mBJ) correction of GGA approximation. Our findings shed light on the significant influence of stacking periodicity on the optoelectronic properties of HgTe/ZnTe SLs. We demonstrate that manipulating layer count is a viable strategy for engineering their optoelectronic characteristics. Additionally, the predicted near-infrared absorption makes these SLs promising candidates for near-infrared detector applications.

A handheld rapid detector of soil total nitrogen based on phase-locked amplification technology

Soil total nitrogen (STN) serves as a critical indicator for agricultural productivity. Rapid STN detection is crucial for nutrient monitoring in farmland and for guiding precision fertilization. Traditional near-infrared spectroscopy-based STN detectors necessitate darkrooms or subterranean settings to negate ambient light interference, restricting their practical use. This study develops a handheld rapid STN detector employing phase-locked amplification technology to address this issue. The device comprises optical, circuit, and control units. The optical unit features a ring-shaped split fiber structure to mitigate soil surface irregularities’ effects on the signal, with a central InGaAs photodiode for signal reception. Eight wavelengths (970 nm, 1050 nm, 1085 nm, 1200 nm, 1300 nm, 1450 nm, 1550 nm, and 1600 nm) are selected for the light sources through an information theory optimized genetic algorithm. The circuit unit employs direct digital synthesis and operational amplifiers for light signal generation and modulation. Reflected soil light signals are demodulated using an InGaAs photodiode and a phase-locked amplifier, effectively filtering ambient light noise. The control unit integrates an STM32F103C8T6 microcontroller and a Raspberry Pi 4B. The STM32 microcontroller manages signal generation, channel selection, frequency control, A/D conversion, and display, while the Raspberry Pi handles data processing, uploading, and transmission. A BP neural network model optimized by genetic algorithms is embedded for real-time STN data acquisition. Cloud-based data storage and visualization are facilitated through the Alibaba Cloud IoT platform. Performance testing reveals the device’s stability and interference resistance, with a standard deviation of electrical signal under varying light conditions below 3 mV. Compared to commercial spectrometers, the correlation coefficient (r) for reflectance data at eight wavebands exceeds 0.9. Accuracy testing shows an R2 above 0.8 and an RMSE of 0.30 g/kg when comparing detector-obtained STN values with standard chemical methods. These results demonstrate the detector’s efficacy in ambient light isolation, stability, and accuracy in agricultural settings, offering technical support for variable fertilization in precision farming.

Flexible visible and near-infrared laser detector based on bismuth sulphide nanorods

The development of a flexible, visible and near-infrared laser detector with fast response holds significant potential for applications in wearable electronics, binary switches, and other fields. In this study, we utilized a flexible transparent polyimide (PI) substrate known for its exceptional thermal resistance up to 400 °C to fabricate an innovative type of flexible laser detector. Systematic investigations demonstrate that the bismuth sulphide nanorods-based laser detector exhibits not only high flexibility and light-weight properties but also excellent linear current characteristics and strong photosensitive dependence on laser light intensity. This research presents a novel approach for the fabrication of high-performance flexible optoelectronic devices.

Short-wavelength infrared light sensing using an electrostatic MEMS resonator integrated with a plasmonic optical absorber

Near-infrared light detectors are employed in various fields such as food inspection for spectroscopic measurements. Despite the fact that photodiodes made of compound semiconductors are used in conjunction with optical filters or monochromators for highly sensitive and wavelength-selective detection of near-infrared light, improvements in device size and cost are necessary for widespread application. Therefore, we propose the use of silicon microelectromechanical systems (MEMS) sensors. This study proposes a single-crystalline Si electrostatic MEMS resonator sensor that is integrated with a gold nanostructure near-infrared light absorber. The device utilizes the resonance frequency shift that occurs due to the thermal stress caused by the heat generated by the near-infrared light on the resonator. A gold nanostructure absorber is mounted on the resonator to enhance photothermal conversion efficiency, enabling the detection of near-infrared light with wavelength selectivity. We fabricated an Au nanostructure-mounted electrostatic transducer and evaluated its performance by measuring its resonance under near-infrared light irradiation. In a light intensity detection experiment, it was found that the relative resonant frequency shift increased linearly with the input in the range below 100 μW, which is consistent with the trend against the input heat. The minimum detection resolution of the light intensity was approximately 5 nW, and the minimum detectable intensity was 3.8 nW. The linear relationship between the optical absorption coefficient and the relative resonance frequency shift was clarified. An array of the devices with different absorption wavelength bands can be used to realize an ultra-compact spectroscopic analysis device without the need for traditional optical filters or monochromators.

Design of a compact wide-band triple grating imaging spectrometer based on freeform surfaces

Wide-band, high spectral resolution, and miniaturized imaging spectrometers have important applications. However, the working band, spectral resolution, and volume of the imaging spectrometers are mutually restricted. To solve this problem, we proposed a method in which multiple working bands share the same optical components except gratings, and the working bands switch with the switching of the working gratings. Based on the freeform surfaces characterized by XY polynomials, we designed a compact wide-band triple grating imaging spectrometer through the design ideas of human-computer interaction and iterative optimization. The imaging spectrometer works in the wavelength band of 200nm∼1600nm, covering ultraviolet (UV), visible, and near-infrared light, and it has a compact optical path volume of 24mm×38mm×80mm. Three gratings with 0.0025 mm, 0.005 mm, and 0.01 mm line spacing are used to realize dispersion with high diffraction efficiency in the bands of 200nm∼400nm, 400nm∼800nm, and 800nm∼1600nm, respectively. The UV detector receives imaging light in the UV band (200nm∼400nm), and the visible near-infrared (VNIR) detector receives imaging light in the visible and near-infrared bands (400nm∼1600nm). The design results show that the spectral resolutions of the three bands are 0.4 nm, 0.8 nm, and 1.6 nm, and the spectral smile and keystone distortion are less than 1.4 µm. The design results have engineering application value.

Low-donor content approach to achieve sensitive narrowband organic photodetectors

Narrowband near-infrared (NIR) detectors are key components for various modern biomedical, agricultural, astronomical sensing as well as monitoring applications. Typically, a narrowband organic photodetector (OPD) requires thick junctions or additional optical elements, which are either tedious or cost-ineffective. Here, we adopt the low-donor content strategy in our thin-film device to realize narrowband spectral features. The much-mitigated aggregation drastically improves shunt resistance and dark current while maintaining decent photocurrent. Upon further dilution, a thinner electron transporting layer can effectively shorten the transient response to reach fast speed. n-i-p and p-i-n device configurations are also compared, which exhibits drastic changes for low-donor content OPDs. The 5 wt% D:A thin-film bulk-heterojunction OPD presents an external quantum efficiency of 49.3% at 770 nm with zero bias, and a high thermal-noise calculated specific detectivity (D*) of 1.0 × 1013 Jones (7.1 × 1012 Jones based on noise spectral density) at 0 V. Such narrowband OPD also shows a fast NIR response of 530 ns/840 ns (rise/fall) when operated at 10 kHz. The results reveal the potential for low-donor-content blend in realizing narrowband photodetection.

Cation-Exchanged quantum Dot-Based high-performance near-infrared photodetectors through surface treatment and passivation

Cation-exchange (CE) is a straightforward method for synthesizing colloidal quantum dots (CQDs) comprising multiple elements. However, the responsivity of photoconductors using cation-exchanged CQDs remains limited due to surface traps induced by the CE process. In this study a flexible near-infrared (NIR) photoconductive detector that exhibits the high responsivity (457 mA/W) under NIR light compared to reported Ag2Se CQD photodetector is fabricated using partially cation exchanged CdxAg2-xSe CQDs. The as-synthesized CdSe CQDs were transformed into CdxAg2-xSe CQDs through the introduction of an Ag precursor to enhance their NIR absorption characteristics and preserve their cubic structures. To mitigate surface traps associated with cation-exchanged CQDs, solution-phase ligand-exchange and post-treatment for surface passivation are incorporated using InBr3. In and Br ions are utilized to fill the surface vacancies of the CQDs and passivate the dangling bonds, reducing nonradiative recombination sites. Structural and optical analyses confirm the passivation of trap states. In addition, indium passivation improves the Seebeck coefficient and mobility, resulting in enhanced responsivity. This study underscores the importance of surface passivation in the CE method, thereby contributing to the future CQDs development with multiple elements.

Comparative study of the near-infrared detection of PbSe fabricated using a sputter deposition method

Near-infrared (NIR) light is used in nondestructive spectroscopies to analyze various compounds in several applications. A PbSe nanocrystal film used in NIR detectors is fabricated using a magnetron sputtering process. The PbSe NIR detectors can be fabricated at a low cost and can operate at ambient temperatures. In this study, the surface morphology and chemical and crystal states of PbSe and its NIR detection performance are investigated and compared with existing reports in the literature. The PbSe film grown by sputtering exhibits nano- and columnar crystal structures, predominantly halite-like (100) face-centered cubic structures. The PbSe film contains PbO and SeO2 and exhibits dual-absorption band-to-band transitions at 0.43 and 0.52 eV. The sputtered PbSe film is used to fabricate an NIR photodetector with a metal-semiconductor-metal structure. The detector shows fast rise and decay times of 0.14 and 0.12 s, respectively, and responsivity of approximately 0.01 A/W under infrared illumination. Based on this study, a low-cost PbSe NIR detector that can operate at room temperature is developed for early fire detection.

High-precision Astrometry and Photometry with the JWST/MIRI Imager

Astrometry is one of the main pillars of astronomy, and one of its oldest branches. Over the years, an increasing number of astrometric works by means of Hubble Space Telescope (HST) data have revolutionized our understanding of various phenomena. With the launch of JWST, it becomes almost instinctive to want to replicate or improve these results with data taken with the newest, state-of-the-art, space-based telescope. In this regard, the initial focus of the community has been on the Near-Infrared detectors on board of JWST because of their high spatial resolution. This paper begins the effort to capture and apply what has been learned from HST to the Mid-InfraRed Instrument (MIRI) of JWST by developing the tools to obtain high-precision astrometry and photometry with its imager. We describe in detail how to create accurate effective point-spread-function (ePSF) models and geometric-distortion corrections, analyze their temporal stability, and test their quality to the extent of what is currently possible with the available data in the JWST MAST archive. We show that careful data reduction provides deep insight on the performance and intricacies of the MIRI imager, and of JWST in general. In an effort to help the community devise new observing programs, we make our ePSF models and geometric-distortion corrections publicly available.

Spot-based measurement of the brighter-fatter effect on a Roman Space Telescope H4RG detector and comparison with flat-field data

We present the measurement and characterization of the brighter-fatter effect (BFE) on a NASA Roman Space Telescope development Teledyne H4RG-10 near-infrared detector using laboratory measurements with projected point sources. After correcting for other interpixel non-linearity effects such as classical non-linearity and inter-pixel capacitance, we quantify the magnitude of the BFE by calculating the fractional area change per electron of charge contrast. We also introduce a mathematical framework to compare our results with the BFE measured on similar devices using autocorrelations from flat-field images. We find an agreement of 18 ± 5% between the two methods. We identify potential sources of discrepancy and discuss future investigations to characterize and address them.

Quaternary nanoparticle array antenna for graphene/silicon near-infrared detector

Infrared imaging chips are crucial for a broad range of military, medicine and biology applications. Although silicon detectors’ on-chip integration technology is matured, their low absorption in near-infrared light results in poor infrared photocurrent response. To increase the photodetector absorption efficiency, antenna-like metal nanoparticles have been widely adopted due to their plasmon resonance effects. Oligomer nanoparticles, including quaternary nanoparticles, exhibit plasmon resonance effects that localize and enhance the light field in a sub-wavelength range. Furthermore, they can interfere with each other to achieve Fano resonance and bound state in continuity, resulting in a stronger localization and enhancement of the electromagnetic field. In this study an array of gold quaternary nanoparticle oligomers is used as the antenna for a graphene/SOI (with 1 μm silicon) heterojunction near-infrared detector. Each oligomer consists of four gold squares, each with a size of 250 nm, forming two pairs of dipoles similar to the orbital hybridization of hydrogen atoms. This thus results in a multi-body coupling structure with bonding state and anti-bonding state. The antenna array parameters, such as the periodic constant, gap between nanoparticles, and angle (<i>θ</i>) between the oligomers, are meticulously adjusted. The optimized device is characterized by using photocurrent and photocurrent mapping, achieving a 2-fold enhancement in photoresponsivity with the maximum value at <i>θ</i> ~ 40°. Notably, a consistent dip in photocurrents is observed for different periods or gap arrays when the angle theta is 20°. The simulation is conducted by using finite-difference time-domain (FDTD), revealing the emergence of Fano-like resonance in the transmittance spectra of the array at approximately 850 nm. The interference caused by the strongly coupling system to the plane coupled leakage field and the nanoparticle plasmon mode results in the formation of a new discrete leakage mode, i.e. the Fano-like resonance. The antenna helps to concentrate and emit the light field energy directionally to the detector, while there is a trade-off between the loss caused by nanoparticles absorption and the leakage energy. The photocurrent reaches a minimal point at a theta angle of 20° angle. At this point, the energy is localized in the oligomers, and the metal absorption loss weakens the plasmon enhancement effect. These findings are further supported by the simulation results of electric field and Poynting vector distribution. These findings indicate an important and promising way to enhance the photo detection efficiency via nanostructured plasmonic antenna.

NIR II-responsive core–shell La2O2S:Er3+@La2O2S nanoparticles towards 1.5 μm photodetection

Schematic diagram of a 1550 nm near-infrared photoelectric detector based on a MAPbI3/La2O2S:2%Er3+@La2O2S structure.

Experimental Analysis of Coherent Velocity Measurement Based on Near-infrared Single-element SPAD Detector

Experimental Analysis of Coherent Velocity Measurement Based on Near-infrared Single-element SPAD Detector

Suppression of the dark current in PbS quantum dot infrared photodetectors through the introduction of a CuInSeS interfacial layer

Lead sulfide (PbS) colloidal quantum dot (CQD) materials are extensively utilized in the fabrication of near-infrared detectors.

(Invited) Epitaxial Growth Technique for Si1−X Sn x Binary Alloy Thin Films

Silicon tin (Si1−x Sn x ) binary alloys are attractive materials for next-generation Si-based photonics and thermoelectronics. The energy band calculations predicted that the conduction band at the Γ point is more rapidly decreased than the others by the Sn substitution, and direct band gap semiconductors can be realized at more than sufficient Sn content [1], although they varied from 25 to 90% by the calculation methods. The corresponding wavelength range will be matched to the optical communication band, suggesting Si1−x Sn x can be applied to near-infrared light source and detector. Another interest is the dramatic reduction of the thermal conductivity by the Sn substitution owing to the mass-difference phonon scattering. Theoretically [2], the thermal conductivity of bulk Si (145 Wm−1K−1 [3]) can be decreased to ~5 Wm−1K−1 by the 10% Sn substitution; the lowest thermal conductivity (3 Wm−1K−1) is obtained at 50% Sn, which is the lowest value among bulk group-IV alloys. The low thermal conductivity achieves high thermoelectric performance and can help to ensure temperature differences within small thermoelectric generators (TEGs) integrated on Si chips, as is the case of Si nanowire TEGs [4].In contrast to the theoretical studies mentioned above, experimental studies are very limited compared with other group-IV alloys such as silicon germanium and germanium tin. Difficulties of the Si1−x Sn x synthesizing are the extremely low solid solubility of Sn in Si (0.1%), a tenth of that in Ge, and the large (∼20%) mismatch between the Si and α-Sn lattices. Nevertheless, some research groups, including us, showed some possibilities to achieve a high Sn content Si1−x Sn x thin films (x>10%) experimentally; reported the optical properties such as photoluminescence and photo-absorption. However, the technology for freely controlling Sn content is still in its infancy; the Si1−x Sn x ’s thermoelectric properties have not been clarified yet. We will discuss the recent progress on the growth techniques of Si1−x Sn x thin films using solid phase epitaxy/crystallization [5-7], molecular beam epitaxy [8,9], sputtering [10], and the potential in thin-film TEGs application. Acknowledgments This work was partly supported by JSPS KAKENHI (Nos. 19K21971, 20H05188, and 21H01366), PRESTO (No. JPMJPR15R2), and CREST (No. JPMJCR19Q5) from JST, the TEPCO Memorial Foundation, and the Naito Research Grant.