Capacitively Coupled Hot-Electron Nanobolometer with SIN Tunnel Junctions
Capacitively Coupled Hot-Electron Nanobolometer with SIN Tunnel Junctions
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具有 SIN 隧道结的电容耦合热电子纳米测辐射热计
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
Mikhail Tarasov
中科院分区：
文献类型：
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作者：
L. Kuzmin;M. Fominsky;A. Kalabukhov;A. Kalabukhov;Dmitri S. Golubev;Mikhail Tarasov
电容耦合热电子纳米热热计（CC-HEB）是最简单、最有效的天线耦合热热计。辐射热计由一个小吸收器组成，通过隧道结连接到超导天线上。用于高频耦合的隧道结也可以在吸收器的小体积中对热电子进行完美的热隔离。同样的隧道结也用于温度测量和电子冷却。由于隧道结的高势垒，这种辐射热计不会受到亚毫米范围内频率的限制，而带有安德烈夫反射镜（A-HEB）的微辐射热计则受到超导间隙的限制。理论分析表明，与用于A-HEB的单结结构相比，双结结构在电流偏置模式下的灵敏度增加了一倍以上。CC-HEB的另一个重要优势是其简单的两层样品制造技术。样品由Cr和Al双层材料制成，以匹配天线的阻抗。电极由铝制成，并在氧化铝层上形成隧道结。隧道结的耦合电容C≈20 fF与10 μm吸收体的电感相结合，形成中心频率约为300 GHz的带通滤波器。辐射热计集成了对数周期和双偶极子平面天线。在温度低至256 mK时测量了测热计结构的温度响应。在我们的实验中，我们观察到dV/dT=1.3 mV/K，对应的响应度S=0.2.109 V/W。对于1 kHz时放大器噪声Vna=3nV/Hz1/2，估计总噪声等效功率NEP=1.5.10-17 W/Hz1/2。本征辐射热计自噪声Vnbol=0.5 nV/Hz1/2对应NEP=3.10-18 W/Hz1/2。为了对辐射热计的灵敏度进行微波评价，我们使用了一个黑体辐射源，该辐射源包括一个薄的NiCr刺激器，放置在低温恒温器的冷板上，在CC-HEB前面，连接到一个扩展的半球蓝宝石透镜。这一测量结果与基于测热计直流响应度的估计一致。
A capacitively coupled hot-electron nanobolometer (CC-HEB) is the simplest and most effective antenna-coupled bolometer. The bolometer consists of a small absorber connected to the superconducting antenna by tunnel junctions. The tunnel junctions used for high-frequency coupling also give perfect thermal isolation of hot electrons in the small volume of the absorber. The same tunnel junctions are used for temperature measurements and electron cooling. This bolometer does not suffer from the frequency limitations in the submillimeter range due to the high potential barrier of the tunnel junctions as does the microbolometer with Andreev mirrors (A-HEB), which is limited by the superconducting gap. Theoretical analyses show that the two-junction configuration more than doubles the sensitivity of the bolometer in current-biased mode compared to the single-junction configuration used for A-HEB. Another important advantage of CC-HEB is its simple two-layer technology for sample fabrication. Samples were fabricated with an absorber made of a bilayer of Cr and Al to match the impedance of the antenna. Electrodes were made of Al and tunnel junctions were formed over the Al oxide layer. The coupling capacitances of the tunnel junctions, C ≈ 20 fF, in combination with the inductance of the 10 μm absorber create a bandpass filter with a central frequency around 300 GHz. Bolometers are integrated with log-periodic and double-dipole planar antennas made of Au. The temperature response of bolometer structures was measured at temperatures down to 256 mK. In our experiment we observed dV/dT=1.3 mV/K, corresponding to responsivity S=0.2.109 V/W. For amplifier noise Vna=3nV/Hz1/2 at 1 kHz the estimated total noise equivalent power is NEP=1.5.10-17 W/Hz1/2. The intrinsic bolometer self noise Vnbol=0.5 nV/Hz1/2 corresponds to NEP=3.10-18 W/Hz1/2. For microwave evaluation of bolometer sensitivity we used a black body radiation source comprising a thin NiCr stimulator placed on the cold plate of cryostat in front of a CC-HEB attached to an extended hemisphere sapphire lens. This measurements were consistent with estimates based on the dc responsivity of the bolometer.