A surface micromachined amorphous Ge x Si 1-x O y bolometer for thermal imaging applications

Ahmed, Aftab; Tait, R. Niall; Oogarah, T.; Liu, H. C.; Denhoff, M. W.; Sproule, G. I.; Graham, M. J.

doi:10.1117/12.567612

Cited by 11 publications

(7 citation statements)

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“…Microbolometers with amorphous germanium silicon oxide (a-Ge x Si 1−x O y ) deposited by RF sputtering have been reported with large TCR (−4.8% K −1 ), large R u (1 × 10 5 VW −1 ), large D * (6.7 × 10 8 cmHz 1/2 W −1 ), low V N (3 × 10 −7 VHz −1/2 ), and low R pixel (7 × 10 5 ) [21].…”

Section: B Comparative Analysis With Literaturementioning

confidence: 98%

Microbolometers Based on Amorphous Silicon–Germanium Films With Embedded Nanocrystals

Moreno

Jiménez

Torres

et al. 2015

IEEE Trans. Electron Devices

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In this paper, we have fabricated and characterized uncooled microbolometers using as infrared element intrinsic amorphous silicon-germanium films with embedded nanocrystals with a dimension in the range of ∼2-4 nm. The presence of nanocrystals in the amorphous films reduces the density of defects, improves the transport properties, and specially improves the films stability against radiation. On the other hand, the combination of silicon and germanium in one alloy allows to improve the film conductivity and the temperature coefficient of resistance (TCR), without the necessity of perform doping. Large values of TCR have been demonstrated in the microbolometers, as large as −6.6% K −1 , which in fact is the largest value reported for this kind of devices, and consequently large detectivity values were obtained in the reported devices (2 × 10 9 cmHz 1/2 W −1 ).

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Section: B Comparative Analysis With Literaturementioning

confidence: 98%

Microbolometers Based on Amorphous Silicon–Germanium Films With Embedded Nanocrystals

Moreno

Jiménez

Torres

et al. 2015

IEEE Trans. Electron Devices

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“…Amorphous germanium silicon oxide (a-Ge Si 1− O ) deposited by RF sputtering also has been reported with large TCR values of −4.8% K −1 [9] and semiconducting yttrium barium copper oxide (YBCO) has been studied as IR sensing film, with large TCR values of −3.4% K −1 [10].…”

Section: Journal Of Nanotechnologymentioning

confidence: 99%

Amorphous Silicon-Germanium Films with Embedded Nanocrystals for Thermal Detectors with Very High Sensitivity

Calleja

Torres

Rosales-Quintero

et al. 2016

Journal of Nanotechnology

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We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nanocrystals in a plasma enhanced chemical vapor deposition (PECVD) reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR), which is a signature of the sensitivity in thermal detectors (microbolometers). Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9% K−1). Our results show that amorphous silicon-germanium films with embedded nanocrystals can be used as thermosensitive films in high performance infrared focal plane arrays (IRFPAs) used in commercial thermal cameras.

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“…VO (nonstochiometric film) in the semiconducting phase is selected as an IR-sensitive material because of its high-temperature coefficient of resistance, low noise, and low resistance, which is compatible with readout electronics. Several other materials can be used for IR detection, including amorphous silicon (a: Si) [28], yttrium barium copper oxide (YBaCuO) [29], silicon germanium (SiGe) [30], silicon germanium oxide (SiGeO) [31], [32], and metals [33]. In this paper, a dual-band microbolometer model is presented.…”

Section: Introductionmentioning

confidence: 99%

Design of Dual-Band Uncooled Infrared Microbolometer

et al. 2011

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This paper describes the design and modeling of a smart uncooled infrared detector with wavelength selectivity in the long-wavelength infrared (LWIR) band. The objective is to enhance the probability of detecting and identifying objects in a scene. This design takes advantage of the smart properties of vanadium dioxide (VO 2 ): it can switch reversibly from an IR-transparent to an IR-opaque thin film when properly triggered. This optical behavior is exploited here as a smart mirror that can modify the depth of the resonant cavity between the suspended thermistor material and a patterned mirror on the substrate, thereby altering wavelength sensitivity. The thermistor material used in the simulation is vanadium oxide (VO X ). The simulation results show that, when VO 2 is used in the metallic phase, it reflects IR radiation back to the suspended VO X and enhances IR absorption in the 9.4-10.8-m band. When the film is switched to the semiconductor phase, it admits most IR radiation, which is then reflected back to the suspended VO X by a patterned gold thin film under an SiO 2 spacer layer. The spacer layer is used to increase the resonant cavity depth underneath the microbolometer pixel. Thus, the peak absorption value is shifted to 8-9.4 m, creating the second spectral band. The detector is designed with a relatively low thermal conductance of 1.71 10 7 W/K to maximize responsivity (R v ) to values as high as 1.27 10 5 W/K and detectivity (D ) to as high as 1 62 10 9 cm Hz 1 2 /W, both at 60 Hz. The corresponding thermal time constant is equal to 2.45 ms. Hence, these detectors could be used for 60-Hz frame rate applications. The extrapolated noise equivalent temperature difference is 14 and 16 mK for the 8-9.4-and 9.4-10.8-m bands, respectively. The calculated absorption coefficients in the two spectral bands were 59% and 65%, respectively.Index Terms-Dual-band infrared (IR) detector, microbolometer, vanadium oxide (VOx).

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A surface micromachined amorphous Ge x Si 1-x O y bolometer for thermal imaging applications

Cited by 11 publications

References 0 publications

Microbolometers Based on Amorphous Silicon–Germanium Films With Embedded Nanocrystals

Microbolometers Based on Amorphous Silicon–Germanium Films With Embedded Nanocrystals

Amorphous Silicon-Germanium Films with Embedded Nanocrystals for Thermal Detectors with Very High Sensitivity

Design of Dual-Band Uncooled Infrared Microbolometer

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