Designing Thermally Uniform Mems Hot Micro-Bolometers

Moelders, Nicholas; Pralle, Martin U.; McNeal, Mark P.; Puscasu, Irina; Last, Lisa; Ho, W.J.; Greenwald, A. C.; Daly, James T.; Johnson, Edward A.

doi:10.1557/proc-729-u5.2

Cited by 12 publications

(8 citation statements)

References 3 publications

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“…Our PhCs provide the platform necessary to realise high-temperature nanophotonics for energy applications, ranging from efficient solar absorbers for solar thermal applications (16)(17)(18)(19), which is characterized by good solar absorption (low reflectance for wavelengths smaller than cutoff wavelength usually in the vicinity of 1.5-2.5 μm depending on operation temperature and solar concentration) and low thermal emittance (high reflectance for wavelengths larger than the cutoff wavelength and angularly selective absorption), to highly efficient selective emitters that are important for realizing both high efficiency and high power density TPV energy conversion systems (14,15). In addition, they can be applied as a high-efficiency near-to mid-infrared radiation source for infrared spectroscopy, night vision, as well as miniaturized on-chip for sensing applications including highly selective gas and chemical sensing (20,21).…”

Section: Resultsmentioning

confidence: 99%

“…This is extremely promising for many unique applications, especially high-efficiency energy conversion systems encompassing hydrocarbon and radioisotope fueled thermophotovoltaic (TPV) energy conversion (13,14) as well as solar selective absorbers and emitters for the emerging field of solar thermal, including solar TPV (15-18) and solar thermochemical production of fuels (19). The selective emitters can also be used as highly efficient infrared radiation sources for infrared spectroscopy and sensing applications including highly selective gas and chemical sensing (20,21).To date, PhCs have been designed to achieve both highly selective narrow-band thermal emission exhibiting wavelength, directional, and polarization selectivity (21-23) as well as wideband thermal emission spectra close to blackbody within the design range but suppressed emission otherwise (12,17,(24)(25)(26)(27). In this report, we focus on the design, optimization, fabrication, and characterization of the high performance broadband selective emitter with critical emphasis on obtaining optimized optical response providing the necessary bandwidth that translates into higher power density imperative for large scale solid-state energy conversion, high-temperature performance, and long-range fabrication precision over large areas.…”

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Enabling high-temperature nanophotonics for energy applications

Yeng

Ghebrebrhan²,

Bermel³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

216

181

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The nascent field of high-temperature nanophotonics could potentially enable many important solid-state energy conversion applications, such as thermophotovoltaic energy generation, selective solar absorption, and selective emission of light. However, special challenges arise when trying to design nanophotonic materials with precisely tailored optical properties that can operate at hightemperatures (>1,100 K). These include proper material selection and purity to prevent melting, evaporation, or chemical reactions; severe minimization of any material interfaces to prevent thermomechanical problems such as delamination; robust performance in the presence of surface diffusion; and long-range geometric precision over large areas with severe minimization of very small feature sizes to maintain structural stability. Here we report an approach for high-temperature nanophotonics that surmounts all of these difficulties. It consists of an analytical and computationally guided design involving high-purity tungsten in a precisely fabricated photonic crystal slab geometry (specifically chosen to eliminate interfaces arising from layer-by-layer fabrication) optimized for high performance and robustness in the presence of roughness, fabrication errors, and surface diffusion. It offers nearultimate short-wavelength emittance and low, ultra-broadband long-wavelength emittance, along with a sharp cutoff offering 4∶1 emittance contrast over 10% wavelength separation. This is achieved via Q-matching, whereby the absorptive and radiative rates of the photonic crystal's cavity resonances are matched. Strong angular emission selectivity is also observed, with shortwavelength emission suppressed by 50% at 75°compared to normal incidence. Finally, a precise high-temperature measurement technique is developed to confirm that emission at 1,225 K can be primarily confined to wavelengths shorter than the cutoff wavelength. E ver since photonic bandgaps were predicted to exist in appropriately designed periodic subwavelength structures (1-3)-i.e., photonic crystals (PhCs), significant interest has garnered in recent years to exploit this property. Coupled with the recent advancements in nanofabrication techniques, many applications have been made possible, ranging from room-and cryogenic-temperature optoelectronic devices for development of all-optical integrated circuits (4), to highly sensitive sensors (5), low-threshold lasers (6), and highly efficient light emitting diodes (7). PhCs also enable us to accurately control spontaneous emission by virtue of controlling the photonic bandgap (1, 8). In particular, metallic PhCs have been shown to possess a large bandgap (9-12) and consequently superior modification of the intrinsic thermal emission spectra is readily achievable. This is extremely promising for many unique applications, especially high-efficiency energy conversion systems encompassing hydrocarbon and radioisotope fueled thermophotovoltaic (TPV) energy conversion (13,14) as well as solar selective absorbers and emitters for the...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Enabling high-temperature nanophotonics for energy applications

Yeng

Ghebrebrhan²,

Bermel³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

216

181

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“…Beyond this scope, highly selective emitters/absorbers can also be applied as highly efficient infrared radiation sources and sensors for infrared spectroscopy and sensing applications, like highly selective gas and chemical sensing. 13,14 Earlier designs for selective absorbers and emitters are based for the most part on multilayer and multimaterial structures as well as metal-dielectric composite coatings, which show restricted suitability for high temperature applications due to their limited thermal material and structural stability. In contrast, we have demonstrated -based on theory, modeling, optimization, and experimental results -that two-dimensional (2D) metallic photonic crystals (PhCs) hold immense potential for high-performance, high-temperature, spectrally and directionally selective thermal emitters.…”

Section: Introductionmentioning

confidence: 99%

Recent developments in high-temperature photonic crystals for energy conversion

Rinnerbauer

Ndao

Yeng

et al. 2012

Energy Environ. Sci.

137

102

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After decades of intense studies focused on cryogenic and room temperature nanophotonics, scientific interest is also growing in high-temperature nanophotonics aimed at solid-state energy conversion. These latest extensive research efforts are spurred by a renewed interest in high temperature thermal-to-electrical energy conversion schemes including thermophotovoltaics (TPV), solar-thermophotovoltaics, solar-thermal, and solar-thermochemical energy conversion systems. This field is profiting tremendously from the outstanding degree of control over the thermal emission properties that can be achieved with nanoscale photonic materials. The key to obtaining high efficiency in this class of high temperature energy conversion is the spectral and angular matching of the radiation properties of an emitter to those of an absorber. Together with the achievements in the field of highperformance narrow bandgap photovoltaic cells, the ability to tailor the radiation properties of thermal emitters and absorbers using nanophotonics facilitates a route to achieving the impressive efficiencies predicted by theoretical studies. In this review, we will discuss the possibilities of emission tailoring by nanophotonics in the light of high temperature thermal-toelectrical energy conversion applications, and give a brief introduction to the field of TPV. We will show how a class of large area 2D metallic photonic crystals can be designed and employed to efficiently control and tailor the spectral and angular emission properties, paving the way towards new and highly efficient thermophotovoltaic systems and enabling other energy conversion schemes based on high-performance high-temperature nanoscale photonic materials.

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“…This is inefficient for many applications, for instance as an infrared source in sensing applications, 1,2 as an emitter in thermophotovoltaic (TPV) energy conversion, 3,4 and as a solar absorber. 5,6 For many of these applications, it is desirable to accurately control thermal radiation such that thermal emission occurs only in certain wavelength ranges over an optimum angular spread.…”

Section: Introductionmentioning

confidence: 99%

Omnidirectional wavelength selective emitters/absorbers based on dielectric-filled anti-reflection coated two-dimensional metallic photonic crystals

et al. 2014

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We demonstrate designs of dielectric-filled anti-reflection coated (ARC) two-dimensional (2D) metallic photonic crystals (MPhCs) capable of omnidirectional, polarization insensitive, wavelength selective emission/absorption. Up to 26% improvement in hemispherically averaged emittance/absorptance below the cutoff wavelength is observed for optimized hafnium oxide filled 2D tantalum (Ta) PhCs over the unfilled 2D Ta PhCs. The optimized designs possess high hemispherically averaged emittance/absorptance of 0.86 at wavelengths below the cutoff wavelength and low hemispherically averaged emittance/absorptance of 0.12 at wavelengths above the cutoff wavelength, which is extremely promising for applications such as thermophotovoltaic energy conversion, solar absorption, and infrared spectroscopy.

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Designing Thermally Uniform Mems Hot Micro-Bolometers

Cited by 12 publications

References 3 publications

Enabling high-temperature nanophotonics for energy applications

Enabling high-temperature nanophotonics for energy applications

Recent developments in high-temperature photonic crystals for energy conversion

Omnidirectional wavelength selective emitters/absorbers based on dielectric-filled anti-reflection coated two-dimensional metallic photonic crystals

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