Reduction of residual stress in polymorphous silicon germanium films and their evaluation in microbolometers

2020 ◽  
Vol 89 (3) ◽  
pp. 30101
Author(s):  
Ricardo Jimenez ◽  
Mario Moreno ◽  
Alfonso Torres ◽  
Roberto Ambrosio ◽  
Aurelio Heredia ◽  
...  
Keyword(s):  
Residual Stress ◽  
Silicon Germanium ◽  
Mechanical Stability ◽  
Thermal Response ◽  
High Sensitivity ◽  
Process Conditions ◽  
Voltage Responsivity ◽  
Thermal Response Time ◽  
Dc Current ◽  
Infrared Vision

Hydrogenated polymorphous silicon germanium (pm-SixGe1–x:H) thin films were deposited by the PECVD technique at 200 °C. Three compositions were investigated by changing the silane/germane gas mixture. It was found that the temperature coefficient of resistance (TCR) varies from 2.25% K−1 to 4.26% K−1 while the electrical conductivity ranges from 9.1 × 10−6 S cm−1 to 3.7 × 10−3 S cm−1. On the other hand, the residual stress of as-deposited films was highly compressive reaching values of nearly 700 MPa. After a thermal annealing of 3 hours, it was observed an acceptable reduction and a slight change towards tensile stress. A thin film with low residual stress and high TCR was chosen to manufacture test microbolometers in order to assess if the thermosensing properties of pm-SixGe1–x:H were not affected. After fabricating the microbolometers, their structural conditions were evaluated by scanning electron microscopy and it was found that the reduction of stress significantly improved their mechanical stability and reduced the warping of the membranes. Finally, test structures were characterized at a chopper frequency of 30 Hz, with a DC current of 2.5 μA in a vacuum environment of 20 mTorr. Voltage responsivity of 1.9 × 106 V/W, detectivity of 4.4 × 108 cm ∙ Hz1/2/W, NEP of 1 × 10−11 W/Hz1/2, NETD of 18 mK and 2 ms of thermal response time were measured. In summary, we have studied different process conditions to obtain better pm-SixGe1–x:H films in terms of their electrical and mechanical properties. In this sense, the results obtained with microbolometers show that pm-SixGe1–x:H is a very attractive material to develop infrared vision systems with high sensitivity.

scholarly journals Fabrication of Microbolometer Arrays Based on Polymorphous Silicon–Germanium

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2716 ◽  
Author(s):  
Ricardo Jimenez ◽  
Mario Moreno ◽  
Alfonso Torres ◽  
Alfredo Morales ◽  
Arturo Ponce ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Mechanical Stability ◽  
Electrical Characterization ◽  
Chemical Vapor ◽  
Amorphous Semiconductor ◽  
Polarization Current ◽  
Infrared Sensors ◽  
Voltage Responsivity ◽  
Germanium Alloy ◽  
Semiconductor Matrix

This work reports the development of arrays of infrared sensors (microbolometers) using a hydrogenated polymorphous silicon–germanium alloy (pm-SixGe1-x:H). Basically, polymorphous semiconductors consist of an amorphous semiconductor matrix with embedded nanocrystals of about 2–3 nm. The pm-SixGe1-x:H alloy studied has a high temperature coefficient of resistance (TCR) of 4.08%/K and conductivity of 1.5 × 10−5 S∙cm−1. Deposition of thermosensing film was made by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, while the area of the devices is 50 × 50 μm2 with a fill factor of 81%. Finally, an array of 19 × 20 microbolometers was packaged for electrical characterization. Voltage responsivity values were obtained in the range of 4 × 104 V/W and detectivity around 2 × 107 cm∙Hz1/2/W with a polarization current of 70 μA at a chopper frequency of 30 Hz. A minimum value of 2 × 10−10 W/Hz1/2 noise equivalent power was obtained at room temperature. In addition, it was found that all the tested devices responded to incident infrared radiation, proving that the structure and mechanical stability are excellent.

scholarly journals Alcohol-based highly conductive polymer for conformal nanocoatings on hydrophobic surfaces toward a highly sensitive and stable pressure sensor

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Jung Joon Lee ◽  
Srinivas Gandla ◽  
Byeongjae Lim ◽  
Sunju Kang ◽  
Sunyoung Kim ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Mechanical Stability ◽  
Exchange Process ◽  
Conductive Polymer ◽  
High Sensitivity ◽  
Fast Response ◽  
Pdms Surface ◽  
Practical Applications ◽  
Sensor Applications ◽  
Water Based

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.

A Method for Evaluating Intensity of Water Cavitation Peening Processing

2011 ◽  
Vol 675-677 ◽  
pp. 747-750
Author(s):  
B. Han ◽  
Dong Ying Ju ◽  
Xiao Guang Yu
Keyword(s):  
Residual Stress ◽  
Process Capability ◽  
Diffraction Method ◽  
Spring Steel ◽  
Bubble Collapse ◽  
Plastic Layer ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
Near Surface ◽  
The Impact

Water cavitation peening (WCP) with aeration, namely, a new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration a standard N-type almen strips of spring steel SAE 1070 was treated byWCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by means of the Almen-scale and X-ray diffraction method, respectively. The optimal fluxes of aeration and the optimal standoff distances were achieved. The maximum of arc height value reach around 150μm. The depth of plastic layer observed from the results of residual stresses is up to 150μm. The results verify the existence of macro-plastic strain in WCP processing. The distributions of residual stress in near-surface under different peening intensity can provide a reference for engineers to decide the optimal process conditions of WCP processing.

Thermal Response Time of LV Fuse Gear in Secondary Substations and Cable Distribution Cabinets

2021 ◽  
Author(s):  
E. Fjeld ◽  
O. D. Sjaastad ◽  
W. Rondeel ◽  
T. R. Eriksen ◽  
F. W. Bekken
Keyword(s):  
Response Time ◽  
Thermal Response ◽  
Thermal Response Time

Experimental Investigation on Intensity and Residual Stress in Superficial Layers Induced by Water Cavitation Peening with Aeration

2008 ◽  
Vol 373-374 ◽  
pp. 754-757 ◽  
Author(s):  
Dong Ying Ju ◽  
B. Han
Keyword(s):  
Residual Stress ◽  
Process Capability ◽  
Diffraction Method ◽  
Spring Steel ◽  
Bubble Collapse ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Enhancement Method ◽  
The Impact

Water cavitation peening (WCP) with aeration is a novel surface enhancement method. A new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration, a standard N-type almen strips of spring steel SAE 1070 was treated by WCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by X-ray diffraction method. The optimal fluxes of aeration and the optimal standoff distances were achieved.

scholarly journals A Rapid, Sensitive, Low-Cost Assay for Detecting Hydrogenotrophic Methanogens in Anaerobic Digesters Using Loop-Mediated Isothermal Amplification

2020 ◽  
Vol 8 (5) ◽  
pp. 740
Author(s):  
Anna M. Alessi ◽  
Bing Tao ◽  
Wei Zhang ◽  
Yue Zhang ◽  
Sonia Heaven ◽  
...  
Keyword(s):  
Low Cost ◽  
Quantitative Measure ◽  
Methanogenic Archaea ◽  
High Sensitivity ◽  
Gas Production ◽  
Isothermal Amplification ◽  
Process Conditions ◽  
Strictly Anaerobic ◽  
Loop Mediated Isothermal Amplification ◽  
Hydrogenotrophic Methanogens

Understanding how the presence, absence, and abundance of different microbial genera supply specific metabolic functions for anaerobic digestion (AD) and how these impact on gas production is critical for a long-term understanding and optimization of the AD process. The strictly anaerobic methanogenic archaea are essential for methane production within AD microbial communities. Methanogens are a phylogenetically diverse group that can be classified into three metabolically distinct lineages based on the substrates they use to produce methane. While process optimization based on physicochemical parameters is well established in AD, measurements that could allow manipulation of the underlying microbial community are seldom used as they tend to be non-specific, expensive, or time-consuming, or a combination of all three. Loop-mediated isothermal amplification (LAMP) assays combine a simple, rapid, low-cost detection technique with high sensitivity and specificity. Here, we describe the optimization of LAMP assays for the detection of four different genera of hydrogenotrophic methanogens: Methanoculleus, Methanothermobacter, Methanococcus, and Methanobrevibacter spp. By targeting archaeal elongation factor 2 (aEF2), these LAMP assays provide a rapid, low-cost, presence/absence indication of hydrogenotrophic methanogens that could be used as a real-time measure of process conditions. The assays were shown to be sensitive to 1 pg of DNA from most tested methanogen species, providing a route to a quantitative measure through simple serial dilution of samples. The LAMP assays described here offer a simple, fast, and affordable method for the specific detection of four different genera of hydrogenotrophic methanogens. Our results indicate that this approach could be developed into a quantitative measure that could provide rapid, low-cost insight into the functioning and optimization of AD and related systems.

Machine learning-based thermal response time ahead energy demand prediction for building heating systems

2018 ◽  
Vol 221 ◽  
pp. 16-27 ◽  
Author(s):  
Yabin Guo ◽  
Jiangyu Wang ◽  
Huanxin Chen ◽  
Guannan Li ◽  
Jiangyan Liu ◽  
...  
Keyword(s):  
Machine Learning ◽  
Response Time ◽  
Energy Demand ◽  
Thermal Response ◽  
Heating Systems ◽  
Demand Prediction ◽  
Thermal Response Time ◽  
Energy Demand Prediction

An Ultrafast Thin-Film Microcalorimeter with Monola Yer Sensitivity (J/m2)

1995 ◽  
Vol 398 ◽  
Author(s):  
S.L. Lai ◽  
P. Infante ◽  
G. Ramanath ◽  
L.H. Allen
Keyword(s):  
Thin Film ◽  
Heating Rate ◽  
Current Pulse ◽  
High Sensitivity ◽  
Melting Process ◽  
Thermal Mass ◽  
Calorimetric Measurements ◽  
Calorimetric Technique ◽  
Dc Current ◽  
Thin Film Membrane

ABSTRACTWe introduce a high-sensitivity (∼1 J/m2) scanning microcalorimeter that can be used to perform direct calorimetric measurements on thin film samples at ultrafast heating rate (∼104 °C/s). This novel microcalorimeter is fabricated by utilizing SiN thin-film membrane technology, resulting in dramatically reduced thermal mass of the system. Calorimetric measurements are accomplished by applying a dc-current pulse to the thin-film metal (Ni) heater which also serves as a thermometer, and monitoring the real-time voltage and current of the heater. The temperature of the system and the energy delivered to the system are then determined. This calorimetric technique has been demonstrated by measuring the melting process of thin Sn films with thickness ranging from 13 to 1000 Å, and shows potential for calorimetric probing of irreversible reactions at interfaces and surfaces, as well as transformations in nanostructured materials.

scholarly journals Patterned Metal/Polymer Strain Sensor with Good Flexibility, Mechanical Stability and Repeatability for Human Motion Detection

Micromachines ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 472 ◽  
Author(s):  
Xu Zheng ◽  
Qing Wang ◽  
Jinjin Luan ◽  
Yao Li ◽  
Ning Wang
Keyword(s):  
Nanoimprint Lithography ◽  
Mechanical Stability ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Human Motion ◽  
Polymer Composite Material ◽  
Metallic Surface ◽  
Smart Systems ◽  
Human Motion Detection ◽  
Metal Polymer

Wearable health monitoring smart systems based on flexible metal films are considered to be the next generation of devices for remote medical practice. However, cracks on the metallic surface of the films and difficulty in repeatability are the key issues that restrict the application of such wearable strain sensors. In this work, a flexible wearable strain sensor with high sensitivity and good repeatability was fabricated based on a patterned metal/polymer composite material fabricated through nanoimprint lithography. The mechanical properties were measured through cyclic tension and bending loading. The sensor exhibited a small ΔR/R0 error line for multiple test pieces, indicating the good mechanical stability and repeatability of the fabricated device. Moreover, the sensor possesses high sensitivity with gauge factors of 10 for strain less than 50% and 40 for strain from 50% to 70%. Various activities were successfully detected in real-time, such as swallowing, closing/opening of the mouth, and multi-angle bending of elbow, which illustrates the proposed sensor’s potential as a wearable device for the human body.

Experimental Measurements of Surface Residual Stress Caused by Nano-scale Contact of Rough Surfaces

2003 ◽  
Vol 795 ◽  
Author(s):  
J. Wang ◽  
P. Shrotriya ◽  
H. H. Yu ◽  
K.-S. Kim
Keyword(s):  
Residual Stress ◽  
High Sensitivity ◽  
Front Surface ◽  
Model Analysis ◽  
Aluminum Surface ◽  
Back Surface ◽  
Dislocation Model ◽  
Surface Residual Stress ◽  
Polycrystalline Aluminum ◽  
Nano Scale

ABSTRACTA previous dislocation model analysis predicts that nano-scale contacts of surface steps induce nucleation of dislocations leading to pro-load and anti-load dislocation segregation near the contact surface. Such dislocation segregation generates a sub-layer of tensile residual stress in a much thicker layer of compressive residual stress near the surface. The sub-layer thickness is expected to be about 50 to 100 times the step height. In order to verify the predictions of the model analysis, experiments are carried out on polycrystalline aluminum surface to determine the existence of the tensile sub-layer. The variation of the residual stress along the thickness direction is measured using a newly developed high sensitivity curvature-measurement interferometer. The interferometer measures the curvature change of the back surface of a plate specimen of about 1.9 mm thickness while the contact-loaded front surface is chemically etched. The residual stress distribution measured with sub-nanometer spatial resolution is compared with analytical predictions.

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