Linear Photodetector Array Research Articles

Van der Waals mid-wavelength infrared detector linear array for room temperature passive imaging.

Passive imaging for mid-wave infrared (MWIR) is resistant to atmospheric pollutants, guaranteeing image clarity and accuracy. Arrayed photodetectors can simultaneously perform radiation sensing to improve efficiency. Room temperature van der Waals (vdWs) photodetectors without lattice matching have evolved rapidly with optimized stacking methods, primarily for single-pixel devices. The urgent need to implement arrayed devices aligns with practical demands. Here, we present an 8 by 1 black phosphorus/molybdenum sulfide (BP/MoS2) vdWs photodetector linear array with a fill-factor of ~77%, fabricated using a temperature-assisted sloping transfer method. The flat interface and uniform thickness facilitate carrier transport and minimize pixel nonuniformities, showing an average peak detectivity (D*) of 2.34 × 109 cm·Hz1/2·W-1 in the mid-wave infrared region. Compared to a single pixel, push-broom scanning passive imaging is eight times more efficient and further enhanced through mean filtering and fast Fourier transform filtering for strip noise correction. Our study offers guidance on vdWs arrayed devices for engineering applications.

Sunflower‐Inspired Light‐Tracking System and Spatial Encryption Imaging based on Linear Flexible Perovskite Photodetector Arrays

AbstractLight‐tracking systems and wide‐angle imaging are garnering increasing interest in the field of artificial intelligence due to their benefits to improve the light collection efficiency. Perovskite photodetectors have become the mainstream choice for their high adsorption coefficient, flex‐compatible properties, and low‐cost solution process. However, the fabrication of precise angle‐sensitive flexible detectors remains challenging due to the uncontrollable deposition of photosensitive layers. Herein, wide‐angle‐sensitive linear flexible perovskite photodetector arrays are successfully fabricated. The device exhibits a broad range of 144°, high‐resolution of 2.8°, and long‐term stability of 3000 cycles. As a proof‐of‐concept demonstration, a sunflower‐inspired light‐tracking system with adaptive following performance is illustrated. Furthermore, spatially encrypted imaging is achieved using linear perovskite photodetector arrays coupled with algorithms. This work confirms the superiority of flexible perovskite photodetectors in angle‐sensing and encryption imaging.

Growth of 100 mm indium antimonide single crystals by modified Czochralski technique

Currently there is a worldwide trend to increase the diameter of crystals grown from elemental semiconductors and semiconductor compounds. According to literary data the diameter of 3–5 semiconductor single crystals grown nowadays is 4 to 6 inches. So far up to 75 mm indium antimonide single crystals have been grown in Russia. Indium antimonide is the element base for the widest field of solid state electronics, i.e., optoelectronics. Indium antimonide is used for the fabrication of 3–5 mm range linear photodetectors and photodetector arrays used as light-sensitive material in heat vision systems. Growth heat conditions have been selected and 100 mm [100] indium antimonide single crystals have been grown using the modified two-stage Czochralski technique. The graphite heating unit has been oversized to accommodate a 150 mm crucible and a 4.5–5 kg load. The results of the work have provided for a substantial increase in the yield of photodetectors. The electrophysical properties of the as-grown single crystals have been studied using the Van der Pau method and proved to be in agreement with the standard parameters of undoped indium antimonide. Using the 9-field etch method of pit counting under an optical microscope the dislocation density in the 100 mm single crystals has been measured to be ≤ 100 cm-2which is similar to that for 50 mm single crystals.

Solar-blind imaging based on 2-inch polycrystalline diamond photodetector linear array

Diamond is a promising ultrawide-bandgap semiconductor, which has drawn much attention in deep-ultraviolet optoelectronics and high-power electronics, due to its unique properties, including the highest thermal conductivity, strong radiation resistance, high breakdown electric field, chemical and thermal stability, and high carrier mobility. However, the optoelectronics applications have been restricted greatly by the small growth size of the single-crystal diamond. In this work, we demonstrate a solar-blind photodetector linear array based on high-quality 2-inch polycrystalline diamond, which has the advantage of large-area growth. The photodetector cells exhibit good uniformity, a responsivity of 45 mA/W at 228 nm with a cut-off wavelength of 240 nm, and a short response time of <20 μs. Clear solar-blind images are obtained by using the photodetector linear array as sensing units. The results reported in this work promise the potential applications of polycrystalline diamond in deep-ultraviolet photodetectors.

High-performance light trajectory tracking and image sensing devices based on a γ-In2Se3/GaAs heterostructure

A high-performance γ-In2Se3/GaAs heterostructure-based photodetector linear array shows potential in optoelectronic applications such as real-time light trajectory tracking and image sensing.

Expansion of the analyte concentration range using self-absorption lines

The width of a spectral line in atomic emission spectral analysis with arc radiation sources is, as a rule, much smaller than the hardware function of the spectral device. Thus, the spectral line shape is determined by the hardware function of the spectral device and can be approximated, for example, by the Voigt function. However, when analyzing standard samples with a wide range of element concentrations, the problem of self-absorption often occurs, due to which the analytical line has to be changed, which is not always possible. We propose to modify the Voigt function by adding a factor that describes self-absorption, by analogy with the Bouguer-Lambert law. The possibility of using the proposed function was evaluated in analysis of standard samples of rocks, ores and sandstones on a Grand-Potok spectral system with a MAÉS analyzer and BLPP-2000 linear photodetector arrays. The use of proposed approximating function is shown to provide an increase in the working range of the calibration curves of Cu 327.3954 nm, Cu 324.7532 nm, Pb 287.3311 nm, Ni 305.0818 nm, and Mo 313.2594 nm by 1 – 3 orders of magnitude.

Testing of MAES analyzers with BLPP-2000 and BLPP-4000 photodetector linear arrays in a “GRAND-POTOK” spectral system

For the development of “Grand-Potok” spectral systems and rapid high-sensitivity scintillation atomic emission spectrometry, the “VMK-Optoelektronika” company created a new BLPP-2000 photodetector linear array. Testing of the array as part of “Grand-Potok” spectral system had shown its advantages over a BLPP-369М1 array in recording scintillations of the gold Au 267.595 nm analytical spectral line. Further studies of the BLPP-2000 detector revealed the need to increase the spectral resolution of the system. For this, a new BLPP-4000 photodetector linear array has been developed. It was expected that its use would improve the resolution of the Grand spectrometer over the entire wavelength range, but a reduction in the sensitivity of the spectrometer could be possible. The objectives of this study were to experimentally compare the resolution and signal-to-noise ratio of the “Grand-Potok” spectral system using BLPP-2000, BLPP-4000, and BLPP-369М1 photodetector linear arrays and contrast the obtained results with the characteristics of the higher-resolution Grand-1500 spectrometer with BLPP-2000, which had shown good performance in determination of noble metals in geological samples with complex matrix. The data on the intensities and widths of the spectral lines were obtained from the spectra of the standard samples of various compositions and used to compare the signal-to-noise ratio and spectral resolution of the systems. The study showed that the use of the new MAES analyzers based on BLPP-4000 linear photodetector arrays in the Grand spectrometer increased the resolution of the instrument by a factor of two, while the signal-to-noise ratio of the instrument decreased by a factor of 4-6, leading to the deterioration of the detection limits in the scintillation arc atomic-emission spectrometry. Nevertheless, Grand spectrometers based on BLPP-4000 could be used instead of higher-resolution Grand-1500 spectrometers without deterioration of the detection limits as its aperture is 5–20 times higher. In addition, the signal-to-noise ratio and the resolution in Grand spectrometers with BLPP-369M1 detector arrays used in analytical laboratories could be increased by replacing the detectors with BLPP-4000 arrays. Keywords: Grand-Potok spectral system, MAES high-speed analyzer, spectral resolution, geological samples, scintillation atomic emission spectrometry (Russian) DOI: http://dx.doi.org/10.15826/analitika.2019.23.1.005 A.A. Dzyuba 1,2 , V.A. Labusov 1,2,3 , and S.A. Babin 1,2 1 Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga, 1, Novosibirsk, 630090, Russian Federation 2 VMK-Optoelektronika, pr. Akademika Koptyuga, 1, Novosibirsk, 630090, Russian Federation 3 Novosibirsk State Technical University, pr. K. Marksa, 20, Novosibirsk, 630073, Russian Federation

Monolithic Waveguide-Based Linear Photodetector Array for Use as Ultracompact Spectrometer

We propose a monolithic spectral waveguide photodetector (SWGPD) concept based on a waveguide with a chemical gradient of the semiconductor alloy forming the absorbing medium that allows for spectrally resolved detection. The chemical gradient correlates the absorption of different wavelengths with the position on the waveguide. The generated charge carriers are collected by a linear array of photodetectors along the waveguide. As model system and proof of concept (Mg,Zn)O alloys in the wurtzite phase (Zn-rich) are considered that allow photon detection in the near ultraviolet spectral region. Our concept allows for high overall detection of (in principle) all photons coupled into the waveguide. The spectral range and resolution are determined by the chemical gradient, the spectral broadening of the absorption edges, and the optical confinement factor. At the same time, the photodetectors can provide high-time resolution, limited by the photodetector geometry.

High-resolution compact spectrometer based on a custom-printed varied-line-spacing concave blazed grating.

We present the modeling, design and characterization of a compact spectrometer, achieving a resolution better than 1.5 nm throughout the visible spectrum (360-825 nm). The key component in the spectrometer is a custom-printed varied-line-space (VLS) concave blazed grating, where the groove density linearly decreases from the center of the grating (530 g/mm) at a rate of 0.58 nm/mm to the edge (528 g/mm). Parametric models have been established to deterministically link the system performance with the VLS grating design parameters, e.g., groove density, line-space varying rate, and to minimize the system footprint. Simulations have been performed in ZEMAX to confirm the results, indicating a 15% enhancement in system resolution versus common constant line-space (CLS) gratings. Next, the VLS concave blazed grating is fabricated via our vacuum nanoimprinting system, where a polydimethylsiloxane (PDMS) stamp is non-uniformly expanded to form the varied-line-spacing pattern from a planar commercial grating master (600 g/mm) for precision imprinting. The concave blazed grating is measured to have an absolute diffraction efficiency of 43%, higher than typical holographic gratings (~30%) used in the commercial compact spectrometers. The completed compact spectrometer contains only one optical component, i.e., the VLS concave grating, as well as an entrance slit and linear photodetector array, achieving a footprint of 11 × 11 × 3 cm3, which makes it the most compact and resolving (1.46 nm) spectrometer of its kind.

Low-light-level readout of a new quantum dots sensor at room temperature

ABSTRACTIn this paper, we present an approach for low-light-level detection based on quantum dots and quantum well(QW) hybrid structure sensor operating at room temperature. The photodetector has AlAs/GaAs/AlAs double barrier structures with a layer self-assembled InAs quantum dots(QDs) and In0.15Ga0.85As QW. The photodetector shows high sensitivity to weak light irradiation and the operating temperature at 300 K. Its photoexcited carrier multiplication factor can reach about 2.35 × 106 at 0.01 picowatts (pW) 632.8 nm light power and −0.5 V bias. And the response voltage is 7−mV at integration time 80 μs. This high multiplication factor is achieved by the InAs QDs and In0.15 Ga0.85As QW induced photovoltaic effect. A high sensitivity micro spectrometer based on the 64 pixels QDs photodetector linear array was developed. The novel micro spectrometer was used to investigate the biological sample. The test results show the spectrometer based on QDs photodetector has higher sensitivity contrast with commercial spectrometer. The high sensitivity features of the spectrometer make it a promising choice for Raman or fluorescence detection.

A Silicon-Based Positive-Intrinsic-Negative Photodetector Double Linear Array on a Thick Intrinsic Epitaxial Layer

To measure small particles in clouds without the optical amplification system, a new type of p—i—n photodetector linear array with 128 diode units altogether is designed and realized. In each die, there are two rows of photodiode line array, and each row has 64 photodiodes. Every photodiode has a size of 100 μm × 100 μm with an individual output, and each of them is isolated by the trenches. The depth of them has the same thickness as that of the epitaxial layer, which is designed to be 30 μm to guarantee sufficient absorption of photons and leave a margin for the diffusion of p-type and n-type region. The detector has been tested with a laser whose wavelength was 650nm and irradiance is 50mW/cm2. The achieved photocurrent is 2 μA. Hence, the current responsivity is about 0.4 A/W, and the external quantum efficiency is 76.45%. The dark current is less than 600 pA. Both of the sufficient absorption of photons and low dark current are achieved by utilizing the thick epitaxial intrinsic layer. Low interference of adjacent photodiodes is also guaranteed by the trenches around the photodiodes. With the obtained performance, the photodetector can be used to measure the diameter of precipitation particles in clouds. Therefore, rainfall can be judged based on the diameter of particles.

TU‐C‐108‐05: High Density Organic Scintillator Arrays for High Resolution Stereotactic Body Radiation Therapy Dosimetry

Purpose: Radiation oncology patients receiving stereotactic body radiation therapy (SBRT) are treated with high dose and high dose rate treatment procedures in which delivered dose should be recorded, and verified for quality assurance and patient safety. We implemented a high resolution scintillating fiber detector array to perform high resolution dosimetry of SBRT fields. Materials: Scintillating fibers have a water equivalent attenuation coefficient, excellent reproducibility, stability and a linear response versus dose, do not require any polarizing voltage, and are water impermeable. We constructed a high resolution dosimeter based on an array of sub‐millimeter organic fiber sensors mounted on a supporting frame that provides support, alignment, and buildup material. The fiber detector interface consists of a high density linear array of high speed linear photodetectors. The analog output is transmitted to a high throughput parallel data acquisition system integrated with a dedicated computer for signal processing, analysis, and recording. The detector was specially designed to perform high resolution dosimetric verification of small SBRT fields delivered with conventional dose rates (600 MU/min) to high dose rate flattening filter free beams (up to 2400 MU/min). Results: We determined fiber sensor sensitivity and linearity response with respect to beam intensity field size and dose. Detector spatial resolution is 0.5 mm and linearity response with respect to beam intensity and field size was within 2% for photon beams from 6MV to 18 MV and electron beams from 6 MeV to 20 MeV. Spatial beam profiles were compared with film dosimetry showing excellent agreement within 3% in the penumbra region. Conclusions: The development of this technology addresses the need for high resolution dosimeters for SBRT. The developed detector provides accurate dose, beam localization, and beam profile verification and will be a valuable tool for quality assurance of SBRT treatments.

A particle counting system using the photodetector array of a CMOS image sensor

In this paper, a particle counting system using a CMOS image sensor is demonstrated. The system utilizes a linear photodetector array as a detection element. Therefore, the particles are detected by multiple detectors simultaneously, in contrast to a single detector in conventional particle counting devices, while maintaining the sensitivity. Another advantage of the proposed system is that particles are detected across the full-channel width which removes the need for a particle-focusing method. Also, the proposed system can easily be integrated with a microfluidic chip fabricated on a transparent substrate, as the counting system is attached under the microchannel and counts the particles optically. Detection of polystyrene microbeads has been tested at a flow rate of 5.15 mm s−1. For 21 measurements, the proposed system showed an average count error of 4.56% and a standard deviation of 3.06% using a proposed compensation algorithm. Potentially, the proposed system can detect even smaller particles simply by utilizing a higher resolution CMOS image sensor.

Surface plasmon resonance in superperiodic metal nanoslits

A superperiodic metal nanoslits device is a surface plasmon resonance optical diffraction grating in which each line of the grating consists of an array of finite number metal nanoslits. The metal nanoslits, upon optical excitations, support localized surface plasmon resonance. The superperiod of the nanoslits causes the coherent radiation of the surface plasmon resonance into the far field with angular dispersion. Therefore, localized surface plasmon resonance in the metal nanoslits can be measured with a CCD or a linear photodetector array. In this Letter, we describe a surface plasmon resonance spectral sensor using a superperiodic gold nanoslits array without using an external optical spectrometer.

Complementary metal-oxide-semiconductor imaging array with laser Doppler blood flow processing

A fully integrated complementary metal-oxide-semiconductor 16×1 linear photodetector array with on-chip signal processing for applications in laser Doppler blood flow imaging has been designed and tested. Analog circuitry is used to provide the transimpedance amplifier, amplification of the modulated (ac) component, and antialiasing filter at each pixel, and also multiplexing of the 16 pixels. Digital signal processing is used to implement the lowpass, bandpass, and frequency-weighted filters, along with the signal averaging conventionally implemented as discrete components in laser Doppler blood flow imaging. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the array is demonstrated using modulated light signals and a vibrating test structure. As the first iteration of the chip, this 16×1 linear array provides an opportunity to evaluate the feasibility of full-field laser Doppler blood flow imaging with on-chip processing, with a view to providing a design that is scalable to a larger linear array or 2-D imaging array.

Design and Characterization of 1×128 In0.53Ga0.47As/InP Photodetector Linear Array with Improved Optical Sensitivity and Shunt Resistance

An InGaAs/InP heterojunction phototransistor (HPT) 1×128 one dimensional array chip with an improved optical sensitivity and shunt resistance has been designed and characterized for the detection of a low light signal intensity. We also present epitaxial structures and an equivalent model for optimizing the optical gain and shunt resistance characteristics. The device operation mechanism and experimental results are discussed. The experimental results show that our device has an optical sensitivity of 46 A/W, which is significantly higher than that of a conventional PIN photodetector with the same light absorbing area. This high sensitivity originates from the optical gain-enhanced device structure. The typical optical gain is approximately 94, indicating that HPTs are 94 times more sensitive than PIN photodetectors. The proposed HPT also has over 100–200 of kΩ shunt resistance and a high optical sensitivity under a low illumination condition, which is sufficient for effective signal conversion through a trans-impedance amplifier circuit. In addition, we also discuss a high-power optical-stress-induced dark current reduction effect that is similar to a thermal-annealing-induced dark current reduction effect. of An optical-stress-induced dark current reduction of approximately 1 order is observed in our experiments.

Method of measuring linear displacements and twist angle by means of a linear array of photodetectors

This paper discusses a method of measuring linear displacements and twist angle by means of a linear array of photodetectors. The conditions for making the measurements unambiguous are determined. © 2005 Optical Society of America

High-Resolution Pseudorandom Encoder with Parallel Code Reading

This paper considers pseudorandom encoder as a new type of absolute encoder with only one code track. It is provided using an especial code technique based on pseudorandom binary sequences. A method for parallel reading of pseudorandom code using linear photodetector array is proposed. The presented solution considerably decreases the basic problem, which is a substantial time needed for the execution of the position measuring. The process of determining the fine and rough position is being divided based on the recorded pseudorandom code, and now, all known pseudorandom/natural code conversion methods can be directly applied, which results in 10 times measurement time reduction in relation to the already known solutions and methods in this field. Ill. 4, bibl. 11 (in English; summaries in Lithuanian, English and Russian).

Interrogation of fibre Bragg gratings with a tilted fibre Bragg grating

A new and efficient interrogation scheme suitable for monitoring the Bragg wavelengths of multiplexed fibre Bragg gratings is presented. The heart of the technique consists of a tilted and chirped fibre Bragg grating placed in front of a photodetector linear array. Throughout the paper the principle of operation is discussed and experimentally validated. The technique presents good characteristics such as a worst-case 3.4 pm wavelength resolution, or an interrogation capability for multiplexed sensors.

Spectrophotopolarimeter based on multiple reflections in a coated dielectric slab

A division-of-amplitude photopolarimeter is described that uses multiple reflections inside a coated dielectric slab at oblique incidence. The first four parallel reflected beams pass through suitably oriented, but fixed, linear analyzers and are intercepted by linear photodetector arrays for spectroscopic polarimetry and ellipsometry. A particular design is presented that uses a parallel-plane fused-silica slab which is coated with an opaque reflecting layer of Ag or Al on the back side and with a transparent ZnS thin film on the front side. Sufficient power is available in the high orders and the instrument matrix is non-singular, so that all four Stokes parameters of the input light can be measured simultaneously, over the visible and near-visible spectral range. © 1998 Elsevier Science S.A.