Research on SIS nanoarray-type high-frequency mixer using Bi-2212 single crystals

采用自熔法生长了高质量的Bi 2Sr 2CaCu 2 O <8+δ>（Bi-2212）单晶。在晶体生长过程中，使用置于氧化铝坩埚上的盖上的砖施加压力（<0.4 N/cm^2）。用此技术获得了零电阻转变温度T_c，零>[约等于] 89 K的高质量单晶。我们还开发了一种新的利用Bi-2212晶体制作叠层本征约瑟夫森结的工艺。为了实现叠层的平坦化，将结窗口周围的晶体浸入盐酸溶液中，使其变成绝缘层。当掺杂浓度低于0.1%时，叠层的平坦化得到充分实现。当浓度大于0.5%时，平面化效果变差。在0.05 ~ 0.2%的浓度范围内，叠层中本征结的数量随浓度的增加而线性增加。的 关于我们 用I-V曲线上的分支数来评价酸处理层的厚度。平面化堆叠中结数的这种良好可控性对于电子学应用（例如高频混频器）是有用的。的电流-电压（I-V）特性的堆栈是均匀的，观察到明显的电阻分支，即使在77 K，这可以解释由高电容约瑟夫森结的串联连接的大滞后。在高于40 K的温度下，我们发现本征结的返回电流Ir强烈地依赖于温度T。我们分析了Ir-T特性，使用简单的磁阻和电容并联结（RCSJ）模型的c轴电阻的温度依赖性的堆栈。基于RCSJ模型的Zappe理论很好地解释了Ir-T特性。这些结果为更好地理解Bi-2212的本征约瑟夫森特性提供了有用的信息。少

High-quality Bi_2Sr_2CaCu_2O_<8+δ>(Bi-2212) single crystals were grown by a self-flux method without mixing and grinding of reagent starting powders. During the crystal growth process, a pressure (<0.4 N/cm^2) was applied using a brick placed on the cap on an alumina crucible. We obtained high-quality single crystals with zero-resistance transition temperature, T_<c,zero>【approximately equal】89K, with this techniques. We also developed new fabrication process of stacked intrinsic Josephson junctions using Bi-2212 crystals. For the planarization of the stacks, the crystal around the junction window was modified to insulating layer by dipping into the solution of hydrochloric acid. For the concentration is lower than 0.1%, the planarization of the stack was fully achieved. For the concentration is higher than 0.5%, however, the planarization was spoiled. The number of intrinsic junctions in the stack linearly increased with increasing the concentration in the range from 0.05 to 0.2%. The … More thickness of the acid-treated layer can be evaluated by the number of the branches in I-V curve. This well controlabillity of the number of the junctions in the planarized stacks is useful for the electronics applications, such as high-frequency mixer. The current-voltage (I-V) characteristics of the stacks were uniform and observed distinct resistive branches with large hysteresis even at 77K, which can be explained by a series connection of highly capacitive Josephson junctions. At higher temperatures than 40K, we found that the return current Ir of the intrinsic junction depended strongly on the temperature, T. We analyzed the Ir-T characteristics using simple resistively and capacitively shunted junction (RCSJ) model in view of the temperature dependence of the c-axis resistance of the stack. The Ir-T characteristics were found to be well explained by the Zappe theory based on the RCSJ model. The present results may be useful information for a better understanding of the Bi-2212 intrinsic Josephson characteristics. Less