CMOS compatible MEMS pyroelectric infrared detectors: from AlN to ScAlN

Ng, Doris K. T.; Ho, Chong Pei; Zhang, Tantan; Liang, Xu; Siow, Li Yan; Chung, Wing Wai; Cai, Hong; Lee, Lennon Y. T.; Zhang, Qingxin; Singh, Navab

doi:10.1117/12.2582707

Cited by 10 publications

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“…The absorption of ∼50% for the 20% ScAlN-based pyroelectric detector with AOGs is lower than that of the 12% ScAlN-based pyroelectric detector previously reported with absorption ∼75% 3,29,36 but higher than that of AlN-based pyroelectric detector which reports absorption ∼25%. 30,36 The high reflection at the ∼4 μm wavelength region which causes lower absorption in the same wavelength region could be caused by the rougher surface 37 of the detector stack (as observed from Figure 2b previously) mainly attributed by the AOGs in the 20% ScAlN layer that induces the rough interface between the ScAlN layer and TiN (as observed from Figure 2c and d previously).…”

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confidence: 62%

“…On the other hand, the reflection spectrum shows high reflection in the ∼4 μm wavelength region. This will subsequently affect the absorption intensity at the same wavelength region, as absorption is calculated by subtracting the measured FTIR transmission and reflection spectra across wavelengths in the range 2–14 μm from 100%. ,, …”

Section: Resultsmentioning

confidence: 99%

“…This will subsequently affect the absorption intensity at the same wavelength region, as absorption is calculated by subtracting the measured FTIR transmission and reflection spectra across wavelengths in the range 2−14 μm from 100%. 3,30,36 Figure 3b shows an FTIR absorption spectrum of this detector stack. The drop in absorption at around the 4 μm wavelength region is mostly due to the high reflection of the detector stack in the same wavelength region as depicted in Figure 3a.…”

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confidence: 99%

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Liang

Chen

et al. 2022

ACS Sens.

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NDIR CO 2 gas sensors using a 10-cm-long gas channel and CMOS-compatible 12% doped ScAlN pyroelectric detector have previously demonstrated detection limits down to 25 ppm and fast response time of ∼2 s. Here, we increase the doping concentration of Sc to 20% in our ScAlN-based pyroelectric detector and miniaturize the gas channel by ∼65× volume with length reduction from 10 to 4 cm and diameter reduction from 5 to 1 mm. The CMOS-compatible 20% ScAlN-based pyroelectric detectors are fabricated over 8-in. wafers, allowing cost reduction leveraging on semiconductor manufacturing. Cross-sectional TEM images show the presence of abnormally oriented grains in the 20% ScAlN sensing layer in the pyroelectric detector stack. Optically, the absorption spectrum of the pyroelectric detector stack across the mid-infrared wavelength region shows ∼50% absorption at the CO 2 absorption wavelength of 4.26 μm. The pyroelectric coefficient of these 20% ScAlN with abnormally oriented grains shows, in general, a higher value compared to that for 12% ScAlN. While keeping the temperature variation constant at 2 °C, we note that the pyroelectric coefficient seems to increase with background temperature. CO 2 gas responses are measured for 20% ScAlN-based pyroelectric detectors in both 10-cm-long and 4-cm-long gas channels, respectively. The results show that for the miniaturized CO 2 gas sensor, we are able to measure the gas response from 5000 ppm down to 100 ppm of CO 2 gas concentration with CO 2 gas response time of ∼5 s, sufficient for practical applications as the average outdoor CO 2 level is ∼400 ppm. The selectivity of this miniaturized CO 2 gas sensor is also tested by mixing CO 2 with nitrogen and 49% sulfur hexafluoride, respectively. The results show high selectivity to CO 2 with nitrogen and 49% sulfur hexafluoride each causing a minimum ∼0.39% and ∼0.36% signal voltage change, respectively. These results bring promise to compact and miniature low cost CO 2 gas sensors based on pyroelectric detectors, which could possibly be integrated with consumer electronics for real-time air quality monitoring.

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confidence: 62%

Section: Resultsmentioning

confidence: 99%

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Liang

Chen

et al. 2022

ACS Sens.

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“…On the other hand, PDs are widely used in the IR range and are produced by industry. Today IR PDs are one of the best devices in uncooled IR detectors, providing a high efficiency of detection of the illuminating radiation, relative short response time, high signal-to-noise ratio, low cost, and high reliability [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Ir Pyroelectric Detector Performance in THZ Range Using Wavelength-Scale Sphere-Based Terajet Effect

Minin¹,

Minin²,

Li³

et al. 2021

PIER Letters

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“…Moreover, the present PD, designed especially for THz range, is expensive and lacks reliability. Presently, PDs are one of the most used devices in uncooled IR detectors, providing a high efficiency of detection of the illuminated radiation, relative short response time, high signal-to-noise ratio, low cost, and high reliability [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Improvement of an InfraRed Pyroelectric Detector Performances in THz Range Using the Terajet Effect

et al. 2021

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An infrared (IR) pyroelectric detector was investigated for terahertz (THz) detection using the principle of the terajet effect, which focuses the beam beyond the diffraction limit. The terahertz beam was coupled to the detector’s optical window through a two-wavelength-dimension dielectric cubic particle-lens based on the terajet effect. We experimentally demonstrate an enhancement of about 6 dB in the sensitivity under excitation of 0.2 THz without degradation of the noise equivalent power value. The results show that the proposed method could be applied to increase the sensitivity of various commercial IR sensors for THz applications that do not require modification of the internal structure, and it may apply also to acoustics and plasmonic detectors.

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CMOS compatible MEMS pyroelectric infrared detectors: from AlN to ScAlN

Cited by 10 publications

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Improvement of Ir Pyroelectric Detector Performance in THZ Range Using Wavelength-Scale Sphere-Based Terajet Effect

Improvement of an InfraRed Pyroelectric Detector Performances in THz Range Using the Terajet Effect

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CMOS compatible MEMS pyroelectric infrared detectors: from AlN to ScAlN

Cited by 10 publications

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Miniaturized CO2 Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO2 Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Improvement of Ir Pyroelectric Detector Performance in THZ Range Using Wavelength-Scale Sphere-Based Terajet Effect

Improvement of an InfraRed Pyroelectric Detector Performances in THz Range Using the Terajet Effect

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector