Infrared Detector Technology Research Articles

Gas Imaging with Uncooled Thermal Imager.

Gas imaging has become one of the research hotspots in the field of gas detection due to its significant advantages, such as high efficiency, large range, and dynamic visualization. It is widely used in industries such as natural gas transportation, chemical, and electric power industries. With the development of infrared detector technology, uncooled thermal imagers are undergoing a developmental stage of technological advancement and widespread application. This article introduces a gas imaging principle and radiation transfer model, focusing on passive imaging technology and active imaging technology. Combined with the actual analysis, the application scenarios using uncooled thermal imaging cameras for gas imaging measurement are analyzed. Finally, the limitations and challenges of the development of gas imaging technology are analyzed.

Infrared HOT Photodetectors: Status and Outlook.

At the current stage of long-wavelength infrared (LWIR) detector technology development, the only commercially available detectors that operate at room temperature are thermal detectors. However, the efficiency of thermal detectors is modest: they exhibit a slow response time and are not very useful for multispectral detection. On the other hand, in order to reach better performance (higher detectivity, better response speed, and multispectral response), infrared (IR) photon detectors are used, requiring cryogenic cooling. This is a major obstacle to the wider use of IR technology. For this reason, significant efforts have been taken to increase the operating temperature, such as size, weight and power consumption (SWaP) reductions, resulting in lower IR system costs. Currently, efforts are aimed at developing photon-based infrared detectors, with performance being limited by background radiation noise. These requirements are formalized in the Law 19 standard for P-i-N HgCdTe photodiodes. In addition to typical semiconductor materials such as HgCdTe and type-II AIIIBV superlattices, new generations of materials (two-dimensional (2D) materials and colloidal quantum dots (CQDs)) distinguished by the physical properties required for infrared detection are being considered for future high-operating-temperature (HOT) IR devices. Based on the dark current density, responsivity and detectivity considerations, an attempt is made to determine the development of a next-gen IR photodetector in the near future.

Room-temperature extended short-wave infrared GeSn photodetectors realized by ion beam techniques

GeSn alloys hold great promise as high-performance, low-cost, near- and short-wavelength infrared photodetectors with the potential to replace the relatively expensive and currently market-dominant InGaAs- and InSb-based photodetectors. In this Letter, we demonstrate room-temperature GeSn pn photodetectors fabricated by a complementary metal-oxide-semiconductor compatible process, involving Sn and P ion implantation and flash-lamp annealing prior to device fabrication. The fabrication process enables the alloying of Ge with Sn at concentrations up to 4.5% while maintaining the high-quality single-crystalline structure of the material. This allows us to create Ge0.955Sn0.045 pn photodetectors with a low dark current density of 12.8 mA/cm2 and a relatively high extended responsivity of 0.56 A/W at 1.71 μm. These results pave the way for the implementation of a cost-effective, scalable, and CMOS-compatible short-wavelength infrared detector technology.

A triple point of water cell-based fixed-point blackbody for radiation thermometry

The radiation temperature metrology above 150 °C relies heavily on the use of physical interpolation equations and known reference temperature (provided by solid–liquid phase transition of high-purity metals and metal-carbon eutectic alloys) fixed-point blackbodies. Recent achievements in thermal infrared detector technologies triggered the extension of the scale interpolation below this temperature down to 0 °C by using the reference temperatures provided by Sn, In, Ga fixed-points and ice-point, where the reference temperature of the later is dependent on external parameters. In this work, we demonstrate that the triple-point of water (TPW) based fixed-point blackbody is the metrologically grounded alternative to the ice-point. For this purpose, a fixed-point blackbody, incorporating only a cavity and large area TPW (LATPW) cell was designed, constructed, and validated for the precise calibration of radiation thermometers (RTs) and thermal cameras at the thermodynamic temperature of TPW. The conceptual design of the LATPW cells is similar to the ones used in contact thermometry, where a thermometer well of the cell is employed as a borehole for a cavity, where the cavity is easily detachable. Four different cavities (two different designs with aperture sizes of 40 mm and 50 mm) and three LATPW cells with two distinct well geometries were comparatively studied in several combinations. The largest absolute temperature difference observed between the primary level reference TPW cell (used in contact thermometry) and the LATPW cells is measured to be only 0.37 mK. Radiometric measurements demonstrate that all radiators maximally reflect the blackbody condition including emissivity close to unity, high uniformity across the aperture and high temporal stability. The simplicity of maintenance and easy in-field usage (only distilled water and dry ice are required) make the TPW blackbodies very versatile for the in-situ calibrations of RTs and thermal cameras, allowing its application in many areas including clinical environments.

Phase diagrams and critical temperatures for coherent and incoherent mixtures of InAs1−xSbx alloys using first-principles calculations

Phase diagram calculations are performed for incoherent and coherent mixtures of an InAs1−xSbx (InAsSb) ternary alloy, which is an important material for the applications to infrared detector technology. Our calculations are based on the cluster expansion approach and Monte Carlo simulations combined with first-principles total energy calculations in the framework of density functional theory with Perdew–Burke–Ernzerhof (PBE) and Heyd–Scuseria–Ernzerhof (HSE) exchange-correlation functionals. Because of a lattice mismatch (∼7%) between InAs and InSb, coherency strain plays an important role for the phase stability of the InAsSb alloys. The alloys without the coherency strain (incoherent mixtures) show a miscibility gap with the critical temperature at ∼700 K with 42% (45%) Sb concentration in PBE (HSE), which is in good agreement with the experimentally determined equilibrium miscibility gap temperature. The alloys with the coherency strain (coherent mixtures) show several ground states whose structures are short period superlattices along the [201] direction. The critical temperature is ∼200 K with 50% Sb concentration in both PBE and HSE, which is reduced by ∼500 K compared to that of incoherent mixtures. This reduction of the critical temperature is consistent with the experimental observation where the homogeneous InAsSb alloy continues to grow inside the empirical miscibility gap.

Figure of merit for infrared detector materials

At present stage of infrared detector technology two material systems, bulk HgCdTe ternary alloys and type-II superlattices are used in fabrication of both mid wavelength infrared and long wavelength infrared photodetectors. Proposal of a new metric, so called “Law 19”, for estimation of the HgCdTe performance photodiodes forces the ultimate properties of HgCdTe photodiodes. In these circumstances, the evaluation for assessing the material merit of novel III-V material systems relative to bulk HgCdTe alloys should be reconsidered. This paper attempts to collect and compare the properties of various material systems in terms of their suitability for active detector region.

Acquisition and Processing Considerations for Infrared Images of Rotating Turbine Blades

Abstract As designers aim to increase efficiency in gas turbines for aircraft propulsion and power generation, spatially resolved experimental measurements are needed to validate computational models and compare improvement gains of new cooling designs. Infrared (IR) thermography is one such method for obtaining spatially resolved temperature measurements. As technological advances in thermal detectors enable faster integration times, surface temperature measurements of rotating turbine blades become possible to capture including the smallest features. This paper outlines opportunities enabled by the latest IR detector technologies for capturing spatially resolved rotating blade temperatures, while also addressing some of the challenges of implementing IR for turbine rigs such as the one in the Steady Thermal Aero Research Turbine (START) Laboratory. This paper documents critical steps in achieving accurate measurements including calibration, integration times, spatial noise, and motion blur. From these results, recommendations are provided for achieving accurate IR measurements collected in a rotating turbine facility to study film cooling.

HgCdTe high operation temperature infrared detectors

Based on the current development direction of infrared detector technology. The advantages of HgCdTe high operation temperature (HOT) infrared detector were analyzed in terms of module weight, shape size, power consumption, environmental adaptability and reliability from the perspective of application requirements of HOT infrared detector. The technical route and research status of HgCdTe HOT infrared detector in Europe and America were summarized. From the perspective of device dark current and noise mechanism, the change of dark current and noise at different operating temperatures and their effects on device performance were analyzed. The basic principles of the process optimization HgCdTe devices based on Hg vacancy n-on-p structure, extrinsic doped HgCdTe HOT devices based on in-doped p-on-n structure and Au doped n-on-p structure, nBn based HOT devices based on barrier structure and non-equilibrium mode HgCdTe HOT devices based on thermally excited carrier auger suppression in absorption layer were summarized. The performance of HgCdTe HOT devices with different technology routes and the technical difficulties in the preparation of detectors were compared and analyzed. Based on the comprehensive analysis of the performance and technical difficulties of HOT devices with different technology routes, the future development direction of HgCdTe HOT device technology was prospected. It is considered that the fully depleted device based on low concentration doping absorption layer has better development potential.

二维半导体红外光电探测器研究进展（特邀）

Infrared detection plays an important role in cutting-edge fields such as biomedicine, smart cities, and space exploration. In recent years, a new type of nanoscale semiconductor represented by two-dimensional materials is one of the candidates for a new generation of infrared photodetection technology. This is due to the fact that some index of two-dimensional materials device have exceeded the theoretical limits of traditional thin-film devices, such as detection sensitivity, ultralow dark current, high working temperature, etc. Two dimensional materials can easily be controlled by local field. In this review, the mechanism of three local fields to achieve high performance at room temperature were introduced in the first part, including ferroelectric local field, the interlayer built-in electric field, and the in-plane built-in electric field. Secondly, we introduced the photoelectric enhancement methods of unilateral depletion heterojunction and surface plasmon structure to solve the problem of low quantum efficiency and low light absorption caused by atomic thin effect of two-dimensional materials. Finally, we showed some applications of two-dimensional materials in infrared photodetection field. The exploration reveals the potential and prospect of the novel two-dimensional semiconductor in the field of infrared photodetection, which provides some new methods and ideas for the new generation infrared detector technology.

InAsSb-Based Infrared Photodetectors: Thirty Years Later On

In 1989, one author of this paper (A.R.) published the very first review paper on InAsSb infrared detectors. During the last thirty years, many scientific breakthroughs and technological advances for InAsSb-based photodetectors have been made. Progress in advanced epitaxial methods contributed considerably to the InAsSb improvement. Current efforts are directed towards the photodetector’s cut-off wavelength extension beyond lattice-available and lattice-strained binary substrates. It is suspected that further improvement of metamorphic buffers for epitaxial layers will lead to lower-cost InAsSb-based focal plane arrays on large-area alternative substrates like GaAs and silicon. Most photodetector reports in the last decade are devoted to the heterostructure and barrier architectures operating in high operating temperature conditions. In the paper, at first InAsSb growth methods are briefly described. Next, the fundamental material properties are reviewed, stressing electrical and optical aspects limiting the photodetector performance. The last part of the paper highlights new ideas in design of InAsSb-based bulk and superlattice infrared detectors and focal plane arrays. Their performance is compared with the state-of-the-art infrared detector technologies.

Bringing Colloidal Quantum Dots to Detector Technologies

AbstractAlthough colloidal quantum dots have a ways to go before they can match the performance of state‐of‐the‐art infrared detector technologies, rapid innovations are advancing their commercialization for low‐cost, high‐resolution infrared sensing and imaging.

640×512数字化InGaAs探测器组件

Digital InGaAs detector significantly orients the development of short wave (SW) infrared detector technology, it not only can increase integrated level of the system, but also can develop the imager’s performance. The key point to realize the digital InGaAs detector is integrating ADC into the readout integrated circuit (ROIC) and realize digital ROIC (DROIC). The 640×512 DROIC was designed and fabricated, it interconnected InGaAs detector focal plane array with In and realized digital InGaAs detector assembly. The proposed digital InGaAs detector assembly was tested, and the measurement results show that its readout noise is 230 μV, peak quantum efficiency is 65%, detectivity under 300 K temperature is 1.2×1012 cm Hz1/2 / W, and the power consumption is 94 mW when frame rate is 60 Hz. The measurement results indicate that the digital InGaAs detector assembly has some features as low readout noise, high linearity, wide transmission bandwidth, good resistance to interference and so on.

Recent infrared detector technologies, applications, trends and development of HgCdTe based cooled infrared focal plane arrays and their characterization

Infrared thermal imaging, using cooled and uncooled detectors, is continuously gaining attention because of its wide military and civilian applications. Futuristic requirements of high temperature operation, multispectral imaging, lower cost, higher resolution (using pixels) etc. are driving continuous developments in the field. Although there are good reviews in the literature by Rogalski [1–4], Martyniuk et al . [ 5 ] and Rogalski et al . [ 6 ] on various types of infrared detectors and technologies, this paper focuses on some of the important recent trends and diverse applications in this field and discusses some important fundamentals of these detectors.

Recent progress on advanced infrared photodetectors

Modern infrared detector technology has a history of nearly eighty years. Since the first PbS photodiode was put into use during the World War II, infrared detectors have achieved significant progress, even the third-generation infrared systems have been proposed. In the past decades, the traditional infrared detectors represented by HgCdTe, InSb and InGaAs have been widely applied in military, remote sensing, communication, bioscience, and space exploration. However, the increasing applications demand higher performance infrared detectors. Especially in recent years, the intelligent infrared detection technique was strongly demanded in many high-tech fields such as artificial intelligence, virtual reality systems and smart city. Therefore, the fabricating of infrared detection systems with smaller size, lighter weight, lower power, higher performance and lower price has become an urgent task. At present, the infrared photodetectors are in an age of rapid change, and many new type of advanced infrared photodetectors come to the fore quickly. For the purpose of summarizing these detectors, they are reviewed covering four parts: microstructure coupled infrared detector, infrared detector based on band engineering, new type of low-dimensional material infrared detector, and new directions for traditional infrared detectors. In the infrared detection systems, these photodetectors can be fully used for their prominent performance. The microstructure coupled infrared detector can improve chip integration with high quantum efficiency. Precise design of band structure will raise the operating temperature for mid and long wavelenth infrared photodetectors. Owing to the unique structures and physical properties, low-dimensional material infrared photodetectors have shown their potential application value in flexibility and room temperature detection systems. The ability of avalanche photodetector to detect the extremely weak signal makes it possible using in the frontier science such as quantum private communication and three-dimensional radar imaging systems. The device based on hot electron effect provides a new idea for far infrared detection. The barrier detectors will reduce the manufacturing cost of traditional materials and the design is also very illuminating for other new materials. In this review, firstly we present the history of infrared photodetectors in short. Then the mechanism and achievements of the advanced infrared photodetectors are introduced in detail. Finally, the opportunities and challenges of infrared detection are summarized and predicted.

Type II Superlattice Infrared Detector Technology at SCD

Semi-Conductor Devices’ long-wave infrared 640 × 512/15-μm pitch type II superlattice detector is based on an XBp design with an InAs/GaSb absorbing layer and an InAs/AlSb barrier layer. The barrier architecture ensures a low, diffusion-limited, dark current and allows stable passivation to all fabrication steps. It is shown that the dark current is about 10 times the Rule 07 value and corresponds to a minority carrier lifetime of about 10 ns, while the quantum efficiency can approach within 10% of the HgCdTe value for realistic detector parameters. Detectors are now being manufactured with a reasonable yield for an operability above 99.5%, and a stable and reproducible noise equivalent temperature difference of < 15 mK when operated at 30 Hz, F/2.7 and 77 K.

紧凑型无热化非制冷红外光学系统设计

With rapid growth of uncooled infrared detector technology, uncooled infrared optical systems are widely used. The uncooled infrared optical system must fulfill the requirements of compact size, large relative aperture, high temperature adaptability and stray light suppression ability. A catadioptric optical system with secondary image is adopted to realize the design parameters of 0.55 ratio of total length and focal length and 0.8 F number. In addition, the optical passive compensation method is used to realize an athermalized design in the temperature range of -40C~50C by matching optical and structural materials properly, and the field stop in the first image can ensure the optical system a high stray light suppression ability. The design result shows that optical system's modulation transfer function in each field is close to the diffraction limit at different temperatures and the system size is compact. Finally, it is proved that this uncooled infrared optical system can meet environmental requirements of airborne and missile application through the actual imaging experiment at high and low temperatures.

Status of Uncooled Infrared Detector Technology at ULIS, France

Status of Uncooled Infrared Detector Technology at ULIS, France

Infrared detectors: Advances, challenges and new technologies

Human knowledge of infrared (IR) radiation is about 200 years old. However it was in the late 20th century that we developed a wide range of smart technologies for detection and started to take advantage for our benefit. Today IR detector technology is in its 3rd generation and comes with challenging demands. Based on the propagation of IR radiation through free space it is divided into different transmission windows. The most interesting for thermal imaging are the mid-wave IR (MWIR) and the long-wave IR (LW IR). Infrared detectors for thermal imaging have a number of applications in industry, security, search & rescue, surveillance, medicine, research, meteorology, climatology and astronomy. Currently high-performance IR imaging technology is mainly based on epitaxially grown structures of the small-bandgap bulk alloy mercury-cadmium-telluride (MCT), indium antimonide (InSb) and GaAs based quantum-well infrared photodetectors (QWIPs), depending on the application and wavelength range. However, they operate at low temperatures requiring costly and bulky cryogenic systems. In addition there is always a need for better performance, which generates possibilities for developing new technologies. Some emerging technologies are quantum dot infrared photodetectors (QDIPs), type-II strained layer super-lattice, and QDIPs with type-II band alignment. In this report a brief review of the current and new technologies for high performance IR detectors, will be presented.

The Potential for Assessing Residual Stress Using Thermoelastic Stress Analysis: A Study of Cold Expanded Holes

Thermoelastic stress analysis (TSA) is a well established tool for non-destructive full-field experimental stress analysis. In TSA the change in the sum of the principal stresses is derived, usually when a component is subjected to a cyclic load. Therefore the mean stress or any residual stress in a component cannot be obtained from the thermoelastic response. However, modifications to the linear form of the thermoelastic equation that incorporate the mean stress may provide a means of establishing the residual stresses. It has also been shown that the application of plastic strain modifies the thermoelastic constant in some materials, causing a change in thermoelastic response, which may also be related to the residual stress. The changes in response due to plastic strain and mean stress are of the order of a few mK and are significantly less than those expected to be resolved in standard TSA. Recent developments in infra-red detector technology have enabled these small variations in the thermoelastic response to be identified, leading to renewed interest in the use of TSA for residual stress analysis in realistic components. The component studied in this work is an aluminium plate that contains a cold expanded hole, hence providing an opportunity to examine any changes in thermoelastic response caused by the residual stress in the neighbourhood of the hole. The variations in thermoelastic response due to residual stress are shown to be measurable and significant; validation of the residual stress field is provided by laboratory X-ray diffraction. The potential for a TSA based approach for residual stress analysis is revisited, and the feasibility of applying it to components containing realistic residual stress levels is assessed.

History of infrared detectors

AbstractThis paper overviews the history of infrared detector materials starting with Herschel’s experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940’s. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ∼3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called “dual-use technology applications.” One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.