Research

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14 pages, 4079 KiB

Open AccessArticle

Electro-Optical Properties of Sputtered Calcium Lead Titanate Thin Films for Pyroelectric Detection

by Elham Mafi, Nicholas Calvano, Jessica Patel, Md. Sherajul Islam, Md. Sakib Hasan Khan and Mukti Rana

Micromachines 2020, 11(12), 1073; https://doi.org/10.3390/mi11121073 - 01 Dec 2020

Cited by 3 | Viewed by 2200

Abstract

We report the deposition and characterization of calcium lead titanate (PCT) thin films for pyroelectric detectors. PCT films of thicknesses ranging from ~250 to 400 nm were deposited on both silicon and Si/SiN/Ti/Au substrates at 13 mTorr pressure by 200W radio frequency sputtering [...] Read more.

We report the deposition and characterization of calcium lead titanate (PCT) thin films for pyroelectric detectors. PCT films of thicknesses ranging from ~250 to 400 nm were deposited on both silicon and Si/SiN/Ti/Au substrates at 13 mTorr pressure by 200W radio frequency sputtering in an Ar + O₂ environment. Substrates were kept at variable temperatures during the deposition. The PCT films were annealed at various temperatures in an O₂ environment for 15 min. X-ray diffraction results confirm the polycrystalline nature of these films. Energy dispersive spectroscopy function of scanning electron microscope showed that the films are stoichiometric (Ca_0.43Pb_0.57) TiO₃ (Ca/Ti = 0.5, Pb/Ti = 0.66). Temperature dependence of capacitance, pyroelectric current, and pyroelectric coefficient was investigated for different PCT films. Our results show that films deposited at 550 °C and 600 °C demonstrate better quality and larger values of the pyroelectric coefficient. On the other hand, the capacitance fabricated on the PCT films at 550 °C showed the highest value of pyroelectric current and pyroelectric coefficient which were 14 pA and at 30 °C was ~2 µC/m²K respectively at a higher temperature. In addition, we used density functional theory to determine the atomic and band structure, real and imaginary parts of dielectric constant and refractive index, and absorption and reflection constants with energy. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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16 pages, 4231 KiB

Open AccessArticle

Performance Comparison of SOI-Based Temperature Sensors for Room-Temperature Terahertz Antenna-Coupled Bolometers: MOSFET, PN Junction Diode and Resistor

by Durgadevi Elamaran, Yuya Suzuki, Hiroaki Satoh, Amit Banerjee, Norihisa Hiromoto and Hiroshi Inokawa

Micromachines 2020, 11(8), 718; https://doi.org/10.3390/mi11080718 - 24 Jul 2020

Cited by 12 | Viewed by 2894

Abstract

Assuming that the 0.6-μm silicon-on-insulator (SOI) complementary metal–oxide–semiconductor (CMOS) technology, different Si-based temperature sensors such as metal-oxide-semiconductor field-effect transistor (MOSFET) (n-channel and p-channel), pn-junction diode (with p-body doping and without doping), and resistors (n⁺ or p⁺ single crystalline Si and n [...] Read more.

Assuming that the 0.6-μm silicon-on-insulator (SOI) complementary metal–oxide–semiconductor (CMOS) technology, different Si-based temperature sensors such as metal-oxide-semiconductor field-effect transistor (MOSFET) (n-channel and p-channel), pn-junction diode (with p-body doping and without doping), and resistors (n⁺ or p⁺ single crystalline Si and n⁺ polycrystalline Si) were designed and characterized for its possible use in 1-THz antenna-coupled bolometers. The use of a half-wave dipole antenna connected to the heater end was assumed, which limited the integrated temperature sensor/heater area to be 15 × 15 µm. Our main focus was to evaluate the performances of the temperature sensor/heater part, and the optical coupling between the incident light and heater via an antenna was not included in the evaluation. The electrothermal feedback (ETF) effect due to the bias current was considered in the performance estimation. A comparative analysis of various SOI bolometers revealed the largest responsivity (R_v) of 5.16 kV/W for the n-channel MOSFET bolometer although the negative ETF in MOSFET reduced the R_v. The noise measurement of the n-channel MOSFET showed the NEP of 245 pW/Hz^1/2, which was more than one order of magnitude smaller than that of the n⁺ polycrystalline Si resistive bolometer (6.59 nW/Hz^1/2). The present result suggests that the n-channel MOSFET can be a promising detector for THz applications. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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16 pages, 3196 KiB

Open AccessArticle

In-Pixel Temperature Sensors with an Accuracy of ±0.25 °C, a 3σ Variation of ±0.7 °C in the Spatial Domain and a 3σ Variation of ±1 °C in the Temporal Domain

by Accel Abarca and Albert Theuwissen

Micromachines 2020, 11(7), 665; https://doi.org/10.3390/mi11070665 - 08 Jul 2020

Cited by 4 | Viewed by 2765

Abstract

This article presents in-pixel (of a CMOS image sensor (CIS)) temperature sensors with improved accuracy in the spatial and the temporal domain. The goal of the temperature sensors is to be used to compensate for dark (current) fixed pattern noise (FPN) during the [...] Read more.

This article presents in-pixel (of a CMOS image sensor (CIS)) temperature sensors with improved accuracy in the spatial and the temporal domain. The goal of the temperature sensors is to be used to compensate for dark (current) fixed pattern noise (FPN) during the exposure of the CIS. The temperature sensors are based on substrate parasitic bipolar junction transistor (BJT) and on the nMOS source follower of the pixel. The accuracy of these temperature sensors has been improved in the analog domain by using dynamic element matching (DEM), a temperature independent bias current based on a bandgap reference (BGR) with a temperature independent resistor, correlated double sampling (CDS), and a full BGR bias of the gain amplifier. The accuracy of the bipolar based temperature sensor has been improved to a level of ±0.25 °C, a 3σ variation of ±0.7 °C in the spatial domain, and a 3σ variation of ±1 °C in the temporal domain. In the case of the nMOS based temperature sensor, an accuracy of ±0.45 °C, 3σ variation of ±0.95 °C in the spatial domain, and ±1.4 °C in the temporal domain have been acquired. The temperature range is between −40 °C and 100 °C. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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9 pages, 6085 KiB

Open AccessArticle

High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers

by Bing Sun and Yiping Wang

Micromachines 2020, 11(3), 270; https://doi.org/10.3390/mi11030270 - 05 Mar 2020

Cited by 9 | Viewed by 2575

Abstract

The conventional methods for monitoring IgG levels suffer from some apparent problems such as long assay time, multistep processing, and high overall cost. An effective and suitable optical platform for label-free biosensing was investigated by the implementation of antibody/antigen immunoassays. The ultrasensitive detection [...] Read more.

The conventional methods for monitoring IgG levels suffer from some apparent problems such as long assay time, multistep processing, and high overall cost. An effective and suitable optical platform for label-free biosensing was investigated by the implementation of antibody/antigen immunoassays. The ultrasensitive detection of IgG levels could be achieved by exploiting the dispersion turning point (DTP) existing in the tapered two-mode fibers (TTMFs) because the sensitivity will reach ±∞ on either side of the DTP. Tracking the resonant wavelength shift, it was found that the fabricated TTMF device exhibited limits of detection (LOD) down to concentrations of 10 fg/mL of IgG in PBS solution. Such immunosensors based on DTP have great significance on trace detection of IgG due to simple detection scheme, quick response time, and miniaturization. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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11 pages, 3651 KiB

Open AccessArticle

A CMOS-Thyristor Based Temperature Sensor with +0.37 °C/−0.32 °C Inaccuracy

by Jing Li, Yuyu Lin, Siyuan Ye, Kejun Wu, Ning Ning and Qi Yu

Micromachines 2020, 11(2), 124; https://doi.org/10.3390/mi11020124 - 22 Jan 2020

Cited by 4 | Viewed by 2601

Abstract

This paper describes a voltage controlled oscillator (VCO) based temperature sensor. The VCOs are composed of complementary metal–oxide–semiconductor (CMOS) thyristor with the advantage of low power consumption. The period of the VCO is temperature dependent and is function of the transistors’ threshold voltage [...] Read more.

This paper describes a voltage controlled oscillator (VCO) based temperature sensor. The VCOs are composed of complementary metal–oxide–semiconductor (CMOS) thyristor with the advantage of low power consumption. The period of the VCO is temperature dependent and is function of the transistors’ threshold voltage and bias current. To obtain linear temperature characteristics, this paper constructed the period ratio between two different-type VCOs. The period ratio is independent of the temperature characteristics from current source, which makes the bias current generator simplified. The temperature sensor was designed in 130 nm CMOS process and it occupies an active area of 0.06 mm². Based on the post-layout simulation results, after a first-order fit, the sensor achieves an inaccuracy of +0.37/−0.32 °C from 0 °C to 80 °C, while the average power consumption of the sensor at room temperature is 156 nW. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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13 pages, 3008 KiB

Open AccessArticle

Dynamic Error Correction of Filament Thermocouples with Different Structures of Junction based on Inverse Filtering Method

by Chenyang Zhao and Zhijie Zhang

Micromachines 2020, 11(1), 44; https://doi.org/10.3390/mi11010044 - 30 Dec 2019

Cited by 1 | Viewed by 2174

Abstract

Since filament thermocouple is limited by its junction structure and dynamic characteristics, the actual heat conduction process cannot be reproduced during the transient thermal shock. In order to solve this problem, we established a thermocouple dynamic calibration system with laser pulse as excitation [...] Read more.

Since filament thermocouple is limited by its junction structure and dynamic characteristics, the actual heat conduction process cannot be reproduced during the transient thermal shock. In order to solve this problem, we established a thermocouple dynamic calibration system with laser pulse as excitation source to transform the problem of the restoring excitation source acting on the surface temperature of thermocouple junction into the problem of solving the one-dimensional (1D) inverse heat conduction process, proposed a two-layer domain filtering kernel regularization method for double conductors of thermocouple, analyzed the factors causing unstable two-layer domain solution, and solved the regular solution of two-layer domain by the filtering kernel regularization strategy. By laser narrow pulse calibration experiment, we obtained experimental samples of filament thermocouples with two kinds of junction structures, butt-welded and ball-welded; established error estimation criterion; and obtained the optimal filtering kernel parameters by the proposed regularization strategy, respectively. The regular solutions solved for different thermocouples were very close to the exact solution under the optimal strategy, indicating that the proposed regularization method can effectively approach the actual surface temperature of the thermocouple junction. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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11 pages, 1420 KiB

Open AccessArticle

Adaptive Nonlinearity Compensation System for Integrated Temperature and Moisture Sensor

by Guohong Chen, Shengjun Zhou, Jie Ni and Hao Huang

Micromachines 2019, 10(12), 878; https://doi.org/10.3390/mi10120878 - 13 Dec 2019

Cited by 3 | Viewed by 2205

Abstract

Measuring temperature and moisture are important in many scenarios. It has been verified that temperature greatly affects the accuracy of moisture sensing. Moisture sensing performance would suffer without temperature calibrations. This paper introduces a nonlinearity compensation technique for temperature-dependent nonlinearity calibration of moisture [...] Read more.

Measuring temperature and moisture are important in many scenarios. It has been verified that temperature greatly affects the accuracy of moisture sensing. Moisture sensing performance would suffer without temperature calibrations. This paper introduces a nonlinearity compensation technique for temperature-dependent nonlinearity calibration of moisture sensors, which is based on an adaptive nonlinear order regulating model. An adaptive algorithm is designed to automatically find the optimal order number, which was subsequently applied in a nonlinear mathematical model to compensate for the temperature effects and improve the moisture measurement accuracy. The integrated temperature and moisture sensor with the proposed adaptive nonlinear order regulating nonlinearity compensation technique is found to be more effective and yield better sensing performance. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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10 pages, 2406 KiB

Open AccessArticle

Highly Sensitive Temperature Sensing Performance of a Microfiber Fabry-Perot Interferometer with Sealed Micro-Spherical Reflector

by Jin Li, Juntong Yang and Jinna Ma

Micromachines 2019, 10(11), 773; https://doi.org/10.3390/mi10110773 - 12 Nov 2019

Cited by 9 | Viewed by 2531

Abstract

A temperature probe has been proposed by inserting a microfiber taper into a silica hollow core fiber with a microsphere end. The sealed air cavity in the microsphere and the inserted microfiber acted as the two reflectors of a Fabry-Perot interferometer, respectively. The [...] Read more.

A temperature probe has been proposed by inserting a microfiber taper into a silica hollow core fiber with a microsphere end. The sealed air cavity in the microsphere and the inserted microfiber acted as the two reflectors of a Fabry-Perot interferometer, respectively. The contribution of both microfiber diameter and cavity length on the interference spectra was analyzed and discussed in detail. The temperature change was experimentally determined by monitoring the wavelength location of the special resonance dip. By filling the air cavity with poly-dimethylsiloxane (PDMS), a high temperature sensitivity of 3.90 nm/°C was experimentally demonstrated. This temperature probe with the diameter of 150 μm and length of 10 mm will be a promising candidate for exploring the miniature or implantable sensors. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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Review

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20 pages, 2777 KiB

Open AccessReview

Thermal and Photo Sensing Capabilities of Mono- and Few-Layer Thick Transition Metal Dichalcogenides

by Andrew Voshell, Mauricio Terrones and Mukti Rana

Micromachines 2020, 11(7), 693; https://doi.org/10.3390/mi11070693 - 17 Jul 2020

Cited by 7 | Viewed by 3645

Abstract

Two-dimensional (2D) materials have shown promise in various optical and electrical applications. Among these materials, semiconducting transition metal dichalcogenides (TMDs) have been heavily studied recently for their photodetection and thermoelectric properties. The recent progress in fabrication, defect engineering, doping, and heterostructure design has [...] Read more.

Two-dimensional (2D) materials have shown promise in various optical and electrical applications. Among these materials, semiconducting transition metal dichalcogenides (TMDs) have been heavily studied recently for their photodetection and thermoelectric properties. The recent progress in fabrication, defect engineering, doping, and heterostructure design has shown vast improvements in response time and sensitivity, which can be applied to both contact-based (thermocouple), and non-contact (photodetector) thermal sensing applications. These improvements have allowed the possibility of cost-effective and tunable thermal sensors for novel applications, such as broadband photodetectors, ultrafast detectors, and high thermoelectric figures of merit. In this review, we summarize the properties arisen in works that focus on the respective qualities of TMD-based photodetectors and thermocouples, with a focus on their optical, electrical, and thermoelectric capabilities for using them in sensing and detection. Full article

(This article belongs to the Special Issue Temperature Sensors—Fundamentals, Detectors, Arrays and Applications)

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