Improvement of Non-Uniform Temperature Distributions in Intrinsic Josephson Junction Stacks
Improvement of Non-Uniform Temperature Distributions in Intrinsic Josephson Junction Stacks
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DOI：
10.1109/tasc.2021.3055448
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发表时间：
2021-08
影响因子：
1.8
通讯作者：
D. Oikawa;K. Tsuzuki;Y. Kumagai;Haruki Mitarai;H. Andoh;T. Sugiura;T. Tsukamoto
中科院分区：
文献类型：
--
作者：
D. Oikawa;K. Tsuzuki;Y. Kumagai;Haruki Mitarai;H. Andoh;T. Sugiura;T. Tsukamoto
太赫兹（THz）电磁（EM）波发射器已经被期望用于应用，因为这些波适合于无损检测、电信技术和其他用途。已知强且相干的THz EM波从大尺寸本征约瑟夫森结（IJJ）堆叠辐射，其中自加热效应相当大并且梅萨中的温度不均匀分布。在这项研究中，我们数值研究和讨论的温度和电流分布在大尺寸的IJJ堆，因为这些参数是很难通过实验研究分析。温度和电流的分布可以通过自洽求解的非线性扩散方程的等效电路的台面，通过考虑温度的依赖性的几个参数。数值结果表明，自加热导致梅萨中心局部温度超过临界温度（$T_{\rm c}$）。为了改善不均匀的温度和电流分布，我们提出了一种改进，其中外部热生成系统放置在梅萨的边缘。通过应用这种措施，由于IJJ梅萨的边缘受到外部加热，因此温度分布得到改善。此外，整个梅萨的局部温度被保持在$T_{\rm c}$以下，并且使用所提出的改进来改善电流$-$电压特性。
Terahertz (THz) electromagnetic (EM) wave emitters have been expected for applications because these waves are suitable for non-destructive inspection, telecommunication technologies, and other uses. Strong and coherent THz EM waves are known to radiate from large-sized intrinsic Josephson junction (IJJ) stacks in which the self-heating effect is considerably larger and the temperatures in the mesa are non-uniformly distributed. In this study, we numerically investigate and discuss the temperature and current distributions in large-sized IJJ stacks because these parameters are difficult to analyze through experimental investigation. The temperature and current distributions can be obtained by self-consistently solving the non-linear diffusion equation in an equivalent circuit of the mesa by considering the temperature dependence of several parameters. As shown in the numerical results, self-heating caused the local temperature of the center in the mesa to exceed the critical temperature ($T_{\rm c}$). To improve the non-uniform temperature and current distributions, we propose an improvement in which an external heat generation system is placed on the edges of the mesa. By applying this measure, the temperature distribution is improved because the edges of the IJJ mesa are heated externally. Furthermore, the local temperatures throughout the mesa were held below $T_{\rm c}$, and the current $-$ voltage characteristics were improved using the proposed improvement.