Development of Superhigh-Frequency Electromagnetic-Wave Detectors Using Grain-Boundary Junctions of BKBO

在<1-x>双晶衬底上制备的Ba_K_xBiO_3（BKBO）晶界结是具有SIS（超导体-绝缘体-超导体）特性的约瑟夫森隧道结。利用BKBO的差距能比金属超导体的间隙能更宽，超高频电磁波的高灵敏度传感器是这些结的应用的候选者。本研究以BKBO晶界结为研究对象，开发用于超高频电磁波探测的SIS混频器，并对低介电常数衬底的使用、结特性的改善以及结集成技术（高频电路）的发展进行了研究.在低介电常数衬底上沉积BKBO薄膜的技术的建立：为了建立高频应用所需的在低介电常数衬底上沉积薄膜的技术，我们试图制备具有高介电常数的BKBO薄膜。 ...更多信息 e Mg上的BKBO薄膜（介电常数：10）。由于在MgO上沉积高质量的BKBO薄膜比在SrTiO_3（STO）上更困难，我们研究了衬底处理、缓冲层等因素的影响，发现在溅射室中沉积前对衬底进行原位退火是有效的，获得了与STO上性能相似的BKBO薄膜。在（100）MgO基片上先在高温下短时间淀积BKBO缓冲层，然后在常温下淀积超导薄膜，得到了高质量的（100）BKBO薄膜.结特性的研究：我们研究了STO结的特性，发现在结的势垒中电磁波的传播速度比其它材料的结的传播速度小一个数量级，这说明了衬底的高介电常数的影响和低介电常数衬底的必要性.高频电路的研究：我们研究了超高频探测器的基本实验电路，包括结和其他组件，如天线等。减

Ba_<1-x>K_xBiO_3(BKBO)grain-boundary junctions fabricated on bicrystal substrates are Josephson tunnel junctions which show the SIS (superconductor-insulator-superconductor) feature. A highly-sensitive sensor for superhigh-frequency electromagnetic-waves is a candidate for the application of these junctions, utilizing the gap energy of BKBO wider than those of metal superconductors. In this research, we intended to develop the SIS mixers for the detection of super high-frequency electromagnetic waves using BKBO grain-boundary junctions, and studies on the use of low-permitivity substrates, the improvement of junction properties and the development of junction integration technology (high-frequency circuits) were carried out.1. Establishment of the technology for the deposition of BKBO thin films on low-permittivity substrates :In order to establish the technology for the deposition of thin films on low-permittivity substrates necessary for high-frequency application, we tried to prepar … More e BKBO thin films on Mg (permittivity : 10). Since the deposition of BKBO thin films of high quality on MgO is more difficult than on SrTiO_3 (STO), we investigated the effect of the substrate treatment, buffer layrs, etc. It was found that the in-situ annealing of the substrate before the deposition in the sputter chamber is effective, and BKBO films which shows properties similar to those on STO were obtained. A buffer BKBO layr deposited at a high substrate temperature for a short time prior to the deposition at the normal temperature for superconducting films gives a (100) BKBO film of high quality on (100) MgO substrate.2. Investigation of junction properties :We investigated the properties of the junctions on STO.The velocity of the electromagnetic wave in the barrier of the junction is an order smaller than that reported for junctions of other materials, which suggests the effect of the high permittivity of the substrate and the necessity of low-permittivity substrates.3. Study of high-frequency circuits :We studied the circuits for the basic experiments of the superhigh-frequency detector including junctions and other components such as antennas, etc. Less