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- Forsberg, Fredrik, et al.
(author)
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Heterogeneous 3D integration of 17 μm pitch Si/SiGe quantum well bolometer arrays for infrared imaging systems
- 2013
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In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:4
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Journal article (peer-reviewed)abstract
- This paper reports on the realization of 17 μm × 17 μm pitch bolometer arrays for uncooled infrared imagers. Microbolometer arrays have been available in primarily defense applications since the mid-1980s and are typically based on deposited thin films on top of CMOS wafers that are surface-machined into sensor pixels. This paper instead focuses on the heterogeneous integration of monocrystalline Si/SiGe quantum-well-based thermistor material in a CMOS-compliant process using adhesive wafer bonding. The high-quality monocrystalline thermistor material opens up for potentially lower noise compared to commercially available uncooled microbolometer arrays together with a competitive temperature coefficient of resistance (TCR). Characterized bolometers had a TCR of -2.9% K-1 in vacuum, measured thermal conductances around 5 × 10-8 W K-1 and thermal time constants between 4.9 and 8.5 ms, depending on the design. Complications in the fabrication of stress-free bolometer legs and low-noise contacts are discussed and analyzed.
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