Thermal characterization of surface-micromachined silicon nitride membranes for thermal infrared detectors

Eriksson, Peter; Andersson, Jan Y.; Stemme, G.

doi:10.1109/84.557531

Cited by 147 publications

(79 citation statements)

References 11 publications

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“…Nevertheless, if successful, atomic manipulations could have dramatic impact on graphene's electrical, magnetic, optical, mechanical, chemical, and thermal properties [1][2][3][4] , leading to novel functionalities that could be exploited in nanoscale devices.…”

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confidence: 99%

Controlled growth of a line defect in graphene and implications for gate-tunable valley filtering

et al. 2014

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Atomically precise tailoring of graphene can enable unusual transport pathways and new nanometer-scale functional devices. Here we describe a recipe for the controlled production of highly regular "5-5-8" line defects in graphene by means of simultaneous electron irradiation and Joule heating by applied electric current. High-resolution transmission electron microscopy reveals individual steps of the growth process. Extending earlier theoretical work suggesting valley-discriminating capabilities of a graphene 5-5-8 line defect, we perform firstprinciples calculations of transport and find a strong energy dependence of valley polarization of the charge carriers across the defect. These findings inspire us to propose a compact electrostatically gated "valley valve" device, a critical component for valleytronics.2 Atomically-precise modification of low-dimensional materials such as graphene is exceedingly challenging since existing experimental techniques rarely achieve atomic precision. Nevertheless, if successful, atomic manipulations could have dramatic impact on graphene's electrical, magnetic, optical, mechanical, chemical, and thermal properties [1][2][3][4] , leading to novel functionalities that could be exploited in nanoscale devices.A recently emerging field is "valleytronics", a zero-magnetic-field analog to spintronics which exploits the quantum mechanical "valley" degree of freedom of charge carriers in graphene 2, 5-10 .At low energies the band structure of single-layer graphene is composed of two energetically degenerate valleys ("Dirac cones"), separated by ~30 nm -1 . 11 The intervalley coupling is quite weak in high quality graphene even at room temperature 12,13 , and hence this additional degree of freedom is a good quantum number. Valley polarization could be used for information processing much as the electron spin degree of freedom is used in spintronics, with the added benefit of temperature insensitivity.Generally, two approaches have been suggested for lifting the degeneracy and thus achieving graphene valley polarization: 1) application of external magnetic field, and 2) using local modifications of the crystalline lattice. The growth process of the 5-5-8 linear defect is intriguing, and we examine it in some detail here. The metastable 5-6 pair generated at the growth-leading end is the key to the growth mechanism. Figures 3a-3c illustrate critical formation steps as determined by TEM. Each experimental image is constructed from an average of 12 single shot TEM images taken in rapid succession to reduce the background noise and to include all possible configurations of the defect. As the line defect grows by one octagon, one carbon atom (marked by a blue dot in the illustrations) is ejected, and a new bond is formed between its nearest neighbors (marked by yellow dots). This process also creates a new 5-6 termination pair, which serves as a seed for continued growth. Since an 6 isolated pentagon cannot be sustained in otherwise ideal graphene 23 , an extended structural irre...

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confidence: 99%

Controlled growth of a line defect in graphene and implications for gate-tunable valley filtering

et al. 2014

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“…Once α and R B,0 are known, the effective thermal conductance, G ef f , may be extracted from the temperature rise of the substrate due to self-heating [34] in the microbolometer element by noting that the biasing power, I 2 B R B is equivalent to the power dissipated by the substrate, G ef f ∆T . This is similar to the approach for Eq.…”

Section: Approach For the Experimental Methodsmentioning

confidence: 99%

“…As briefly mentioned earlier, G ef f consists of a number of components [17], one of which is a thermal conductance component attributed to heat loss between the suspended membrane and the substrate via the support beams, referred to as the beam or leg thermal conductance, G leg and is given by [13,23] It has also recently been proposed to include the constriction resistance that results when two thermal conducting paths of different widths are connected, which leads to a constriction effect experienced by the heat flow. This results in an additional radial thermal resistive component [13,24,25].…”

Section: Operating Principles Of Microbolometersmentioning

confidence: 99%

“…They rely on the fact that the mechanism for determining air pressure is highly linked to the gaseous thermal conduction component. [12,17,18]. It has also been proposed for metal thin-film microbolometers that an improved surface area is achieved when including a portion of the support beam [19], as well as the side-wall thermal conduction associated with the plate and additional beam area [20].…”

Section: Introductionmentioning

confidence: 99%

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An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Schoeman

Plessis

2016

Sensors and Actuators A: Physical

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This work presents a detailed overview of the analytic methods for calculating the beam and gaseous thermal conductance components associated with uncooled VO x microbolometers. The conventional method to calculate the gaseous component relies on the assumption that the entire plate is maintained at a uniform temperature, thus the surface area of the plate is used for the calculation. We have observed using an industry leading multiphysics simulator that this assumption is not strictly true for VO x microbolometers as the conduction pattern exhibits an elliptical shape. Based on this, we have developed and propose an analytic method that employs an elliptical surface area scaled appropriately with the device dimensions to obtain an estimate of the average temperature conduction pattern. Prototype devices were manufactured and experimentally characterised. The devices exhibit thermal conduction characteristics comparable to those in literature and industry, and we could achieve 0.5 µW/K under vacuum conditions and 15 µW/K at atmospheric pressure with a TCR of −1 %/K. However, both simulated and experimental result sets of the gaseous thermal conductance exhibit large deviations from the conventional analytic method, on average approximately 40 %. The proposed method reduces this average error significantly to less than 10 % when compared to the simulated results.

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“…In general, the thermal behavior of a microbolometer detector can be evaluated by the electro-thermal analogy [2,5]. The electrical and thermal properties of a single pixel of a microbolometer array can be estimated through the measurement of electrical resistance, but it is difficult to measure thermal distribution over the active area.…”

Section: Introductionmentioning

confidence: 99%

Thermal Characterization of Individual Pixels in Microbolometer Image Sensors by Thermoreflectance Microscopy

Ryu¹,

Choi²,

Kim³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

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Abstract-Thermal characterization of individual pixels in microbolometer infrared image sensors is needed for optimal design and improved performance. In this work, we used thermoreflectance microscopy on uncooled microbolometer image sensors to investigate the thermal characteristics of individual pixels. Two types of microbolometer image sensors with a shared-anchor structure were fabricated and thermally characterized at various biases and vacuum levels by measuring the temperature distribution on the surface of the microbolometers. The results show that thermoreflectance microscopy can be a useful thermal characterization tool for microbolometer image sensors.

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Thermal characterization of surface-micromachined silicon nitride membranes for thermal infrared detectors

Cited by 147 publications

References 11 publications

Controlled growth of a line defect in graphene and implications for gate-tunable valley filtering

Controlled growth of a line defect in graphene and implications for gate-tunable valley filtering

An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Thermal Characterization of Individual Pixels in Microbolometer Image Sensors by Thermoreflectance Microscopy

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