Low-Cost Microbolometer Type Infrared Detectors

Yu, Le; Guo, Yaozu; Zhu, Haoyu; Luo, Mingcheng; Han, Ping; Ji, Xiaoli

doi:10.3390/mi11090800

Cited by 52 publications

(30 citation statements)

References 93 publications

(155 reference statements)

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“…Si 1-x Sn x alloys of compositions within the range of our samples are shown to adequately follow Vegard's law, [1][2][3] which, for our samples, reads as follows…”

Section: Bandgap Estimations For Si 1-x Sn X Alloysmentioning

confidence: 99%

“…This active temperature sensing layer converts the change in temperature induced by the absorbed infrared radiation into a change in electrical resistance, which is then converted to an electrical signal and digitized by the complementary metaloxide-semiconductor (CMOS) read-out integrated circuit (ROIC) and, finally, translated into an image. [1,2] A successful thermistor material ought to possess a high TCR, moderate resistivity for CMOS ROIC impedance matching, low 1/f noise, and, preferably, CMOS process compatibility. [3] The most important property of the bolometric thermometer thin film is TCR.…”

Section: Introductionmentioning

confidence: 99%

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Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

ElGhonimy

Abdel‐Rahman

Hezam

et al. 2021

Physica Status Solidi (b)

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Herein, the prospect of using amorphous Si1–x Sn x alloys as alternative temperature‐sensing active materials in microbolometers is evaluated by studying their temperature‐dependent resistive properties along with their infrared optical properties. Si1–x Sn x thin films (200 nm thick), with varying Sn concentrations, are prepared at room temperature by cosputtering from Si and Sn targets using simultaneous radio frequency and DC magnetron sputter deposition. Low beam energy X‐ray microanalysis is used to estimate the atomic concentrations of the prepared films. Atomic force microscopy analysis shows an increase in the root‐mean‐square surface roughness of the prepared Si1–x Sn x thin films, with increasing Sn content. Sheet resistance versus temperature measurements are performed yielding temperature coefficients of resistance of 3.25, 2.65, and 1.72% K−1 at resistivity values of 116.18, 27.36, and 2.34 Ω cm for Sn concentrations of 35%, 44%, and 48%, respectively. Infrared ellipsometry measurements are performed to extract the optical properties of the Si1–x Sn x thin films and optical simulations confirm that a Fabry–Pérot cavity microbolometer configuration containing an Si1–x Sn x thin film can achieve high absorptance in the 8–12 μm band. This study shows that Si1–x Sn x alloys are a suitable, simple, and low‐cost replacement for thermometer layers used in uncooled infrared microbolometers.

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“…Si 1-x Sn x alloys of compositions within the range of our samples are shown to adequately follow Vegard's law, [1][2][3] which, for our samples, reads as follows…”

Section: Bandgap Estimations For Si 1-x Sn X Alloysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

ElGhonimy

Abdel‐Rahman

Hezam

et al. 2021

Physica Status Solidi (b)

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“…These detectors can be divided into pyroelectric detectors, thermopile detectors, microbolometer detectors (hereinafter referred to as bolometers) [23]. The bolometer's technical route has become the mainstream technical direction [24]. The most used sensitive materials for the bolometer are vanadium oxide (VO x ) and amorphous silicon (α-Si) [25][26][27].…”

Section: Introduction 1context and Backgroundmentioning

confidence: 99%

Factors Influencing Temperature Measurements from Miniaturized Thermal Infrared (TIR) Cameras: A Laboratory-Based Approach

Wan

Brede

Śmigaj

et al. 2021

Sensors

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The workflow for estimating the temperature in agricultural fields from multiple sensors needs to be optimized upon testing each type of sensor’s actual user performance. In this sense, readily available miniaturized UAV-based thermal infrared (TIR) cameras can be combined with proximal sensors in measuring the surface temperature. Before the two types of cameras can be operationally used in the field, laboratory experiments are needed to fully understand their capabilities and all the influencing factors. We present the measurement results of laboratory experiments of UAV-borne WIRIS 2nd GEN and handheld FLIR E8-XT cameras. For these uncooled sensors, it took 30 to 60 min for the measured signal to stabilize and the sensor temperature drifted continuously. The drifting sensor temperature was strongly correlated to the measured signal. Specifically for WIRIS, the automated non-uniformity correction (NUC) contributed to extra uncertainty in measurements. Another problem was the temperature measurement dependency on various ambient environmental parameters. An increase in the measuring distance resulted in the underestimation of surface temperature, though the degree of change may also come from reflected radiation from neighboring objects, water vapor absorption, and the object size in the field of view (FOV). Wind and radiation tests suggested that these factors can contribute to the uncertainty of several Celsius degrees in measured results. Based on these indoor experiment results, we provide a list of suggestions on the potential practices for deriving accurate temperature data from radiometric miniaturized TIR cameras in actual field practices for (agro-)environmental research.

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“…In this regards, amorphous-Si (a-Si), vanadium oxide, and some metals have been adopted as a resistive layer of the microbolometer [1,7]. Particularly, the a-Si based microbolometers are preferential for commercializing the thermal imaging system [17,18], due to their high TCR and full compatibility with the Si-CMOS processing technology. However, the a-Si layer exhibits high resistivity and considerable thermal noise due to the operation at room temperature [19,20], which leads to the lower signal-to-noise Sensors 2021, 21, 6722 2 of 13 ratio (S/N) than that of the cooling-type quantum IR sensors.…”

Section: Introductionmentioning

confidence: 99%

Noise Improvement of a-Si Microbolometers by the Post-Metal Annealing Process

Song

Park

et al. 2021

Sensors

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To realize high-resolution thermal images with high quality, it is essential to improve the noise characteristics of the widely adopted uncooled microbolometers. In this work, we applied the post-metal annealing (PMA) process under the condition of deuterium forming gas, at 10 atm and 300 °C for 30 min, to reduce the noise level of amorphous-Si microbolometers. Here, the DC and temperature coefficient of resistance (TCR) measurements of the devices as well as 1/f noise analysis were performed before and after the PMA treatment, while changing the width of the resistance layer of the microbolometers with 35 μm or 12 μm pixel. As a result, the microbolometers treated by the PMA process show the decrease in resistance by about 60% and the increase in TCR value up to 48.2% at 10 Hz, as compared to the reference device. Moreover, it is observed that the noise characteristics are improved in inverse proportion to the width of the resistance layer. This improvement is attributed to the cured poly-silicon grain boundary through the hydrogen passivation by heat and deuterium atoms applied during the PMA, which leads to the uniform current path inside the pixel.

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Low-Cost Microbolometer Type Infrared Detectors

Cited by 52 publications

References 93 publications

Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

Amorphous SiSn Alloy: Another Candidate Material for Temperature Sensing Layers in Uncooled Microbolometers

Factors Influencing Temperature Measurements from Miniaturized Thermal Infrared (TIR) Cameras: A Laboratory-Based Approach

Noise Improvement of a-Si Microbolometers by the Post-Metal Annealing Process

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