4:00 PM - 4:15 PM
▲ [13p-N105-10] Infrared bolometric detection at room temperature using MEMS beam resonators
Keywords:MEMS technology, Terahertz radiation, Infrared
Thermal detectors, such as bolometers, pyroelectric detectors and Golay cells are the most commonly used broadband THz detectors. However, thermal detectors usually have low operation speed, which limits the measurement speeds. Recently, we proposed and realized a room-temperature operated, all electrically driving and detecting, sensitive and fast thermometer structure using a doubly clamped microelectromechanical (MEMS) resonator for bolometer applications. When an infrared radiation is incident on a NiCr film absorber deposited on the MEMS beam surface, a stress is generated in the beam due to thermal expansion, leading to a reduction in the mechanical resonance frequency. The MEMS detects the shift in its resonance frequency caused by heating and works as a very sensitive and fast bolometer.
We measured terahertz (THz) responsivity spectrum of the MEMS bolometers by using a blackbody light source and a Fourier transform spectrometer. Two peaks observed near the TO and LO phonon frequencies of GaAs originate from an interplay between strong reflection in the Reststrahlen band and strong absorption at the TO phonon frequency in the GaAs MEMS beam. The response spectrum of MEMS bolometers in the mid- and near-infrared range is also measured. The signal reaches maximum at around 2400 cm-1 and decreases for higher frequencies. Due to their fast detection speed, MEMS bolometers even show considerable responsivities in near-infrared frequencies (f > 4000 cm-1), where the responsivities of commercial TGS pyroelectric detector almost vanishes. The responsivity dip around 2900 cm-1 observed in the spectrum originates from the absorption in vacuum grease between sample and chip carrier. The results demonstrate that MEMS bolometers are a very good candidate for the broadband sensitive and fast infrared detection.
We measured terahertz (THz) responsivity spectrum of the MEMS bolometers by using a blackbody light source and a Fourier transform spectrometer. Two peaks observed near the TO and LO phonon frequencies of GaAs originate from an interplay between strong reflection in the Reststrahlen band and strong absorption at the TO phonon frequency in the GaAs MEMS beam. The response spectrum of MEMS bolometers in the mid- and near-infrared range is also measured. The signal reaches maximum at around 2400 cm-1 and decreases for higher frequencies. Due to their fast detection speed, MEMS bolometers even show considerable responsivities in near-infrared frequencies (f > 4000 cm-1), where the responsivities of commercial TGS pyroelectric detector almost vanishes. The responsivity dip around 2900 cm-1 observed in the spectrum originates from the absorption in vacuum grease between sample and chip carrier. The results demonstrate that MEMS bolometers are a very good candidate for the broadband sensitive and fast infrared detection.