Epitaxial superconducting tunnel diodes for light detection applications
Epitaxial superconducting tunnel diodes for light detection applications
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用于光检测应用的外延超导隧道二极管
DOI：
10.1364/ome.395919
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发表时间：
2020
影响因子：
2.8
通讯作者：
A. Hayat
中科院分区：
文献类型：
--
作者：
K. Balasubramanian;J. Wright;O. Zohar;Boaz Taitler;S. Bouscher;H. Xing;D. Jena;A. Hayat
我们展示了外延集成的纳米级超导隧道二极管，它是通过在氮化镓薄膜上使用氮化铌实现的。调整生长条件可降低界面缺陷密度，并使界面隧穿特性中出现超导相干峰。超导体中的无序程度与不同区域的序参量值的变化相关。纳米级层的外延集成能够精确控制界面处超导体的质量，进而控制序参量值的变化。在序参量值具有固定变化的情况下，对界面处超导序参量呈正态分布进行的数值计算与不同温度下测量的界面输运特性紧密吻合。随后发现，在微分电导率测量中观察到的强亚带隙非线性对光子入射敏感，因此可作为光电探测器。将超导界面与氮化镓等半导体层一起使用可实现灵敏度可调性，并能够进行大规模器件制造和集成。
We demonstrate epitaxially integrated nanoscale superconductor tunnel diodes, realized using NbN on GaN thin films. Tuning the growth conditions leads to reduced interface defect density and to the emergence of the superconducting coherence peaks in the interface tunneling characteristics. The degree of disorder in the superconductor is correlated with the variance in the order parameter value of different domains. Epitaxial integration of the nanoscale layers allowed precise control on the quality of the superconductor at the interface, and, by extension, the variance in the order parameter value. The numerical calculations taking a normal distribution of superconducting order parameter at the interface with a fixed variance in its order parameter values closely match the measured interface transport characteristics at different temperatures. Strong sub-gap nonlinearity observed in the differential conductivity measurements were subsequently shown to be sensitive to photon incidence, thereby acting as a photodetector. Usage of superconducting interfaces with semiconducting layers such as GaN permit sensitivity tunability and enable large scale device fabrication and integration.