Nanoelectromechanical infrared detector
Nanoelectromechanical infrared detector
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纳米机电红外探测器
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
S. Schmid
中科院分区：
文献类型：
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作者：
Markus Piller;N. Luhmann;Miao;S. Schmid
红外 (IR) 辐射的灵敏检测是当今现代世界的一项重要任务。最先进的非制冷热红外探测器的灵敏度仍然比基本光子噪声极限高出几个数量级。基于温度敏感的微机械和纳米机械谐振器的热探测器是获得改进的热红外探测器的有前途的方法。在这里，我们提出了一种基于 1 mm×1 mm 大型纳米机电鼓谐振器的非制冷红外探测器，该谐振器由 50 nm 厚的低应力氮化硅 (SiN) 制成。该探测器采用氮化钛吸收器，在整个中红外范围内吸收率为 ∼30%。检测器鼓通过锁相环以其共振频率被驱动。吸收的红外辐射导致鼓的振荡频率出现明显的失谐。我们在室温下、噪声带宽为 25 Hz 时测得艾伦偏差为 σA = 5.5 × 10−7。当响应度为 R = 343 W−1 时，对于波长为 9.5 µm 的红外光束，灵敏度定义为噪声等效功率 (NEP)，NEP = 320 pW/rtHz。对于该测量，红外光束焦点直径等于鼓尺寸。对于小于 ∼ 100 μm 的焦斑尺寸，鼓的响应度提高了十倍。对于较小的点，响应度保持恒定。基于此分析，我们预测对于小于 100 μm 的红外光斑尺寸，灵敏度约为 30 pW/rtHz。检测器可以通过例如进一步改进将拉伸预应力优化至较低值或通过提高吸收率。
The sensitive detection of infrared (IR) radiation is a essential task in today’s modern world. The sensitivity of the state-of-the-art uncooled thermal infrared detectors is still several orders of magnitude above the fundamental photon noise limit. Thermal detectors based on temperature sensitive micro- and nanomechanical resonators are a promising approach to obtain improved thermal IR detectors. Here, we present an uncooled infrared detector based on a 1 mm×1 mm large nanoelectromechanical drum resonator made of 50 nm thick low-stress silicon nitride (SiN). The detector features a titanium nitride absorber with an absorptivity of ∼30% over the entire mid-IR range. The detector drum is driven at its resonance frequency by means of a phase-locked loop. Absorbed IR radiation results in an observable detuning of the drum’s oscillation frequency. We measured an Allan deviation of σA = 5.5 × 10−7 at room temperature at a noise bandwidth of 25 Hz. With a responsivity of R = 343 W−1 this results in a sensitivity defined as noise equivalent power (NEP) of NEP = 320 pW/rtHz for an IR beam at a wavelength of 9.5 µm. For this measurement, the IR beam focus spot diameter was equal to the drum size. The drum’s responsivity improves by a factor of ten for a focal spot size smaller than ∼ 100 μm. For smaller spots the responsivity remains constant. Based on this analysis we predict a sensitivity of ∼ 30 pW/rtHz for an IR spot size smaller than 100 μm. The detector can be improved further by e.g. optimizing the tensile pre-stress to a lower value or by improving the absorptivity.