超导磁通量子比特的制备及Al/AlO_x/Al隧道结特性参数  

Fabrication of superconducting flux quantum bits and the feature parameters of Al/AlO_x/Al tunnel junctions

作　　者：王林[1] 许伟伟[1] 翟计全[1] 李晓虎[1] 孙国柱[1] 吴培亨[1] 

机构地区：[1]南京大学电子科学与工程学院,南京210093

出　　处：《科学通报》2014年第27期2728-2733,共6页Chinese Science Bulletin

基　　金：国家重点基础研究发展计划(2011CBA00107;2011CBA00202);国家自然科学基金(61371036;11234006;11227904);江苏省自然科学基金(BK2012013);中国工程物理研究院太赫兹重点实验室基金(CAEPTHZ201206)资助

摘　　要：超导量子比特作为利用约瑟夫森结实现量子位的方案之一,具有易集成、易与外界耦合等优点.用双层光刻胶通过深紫外光曝光制备悬空掩膜结构,Al作为超导材料,采用电子束斜蒸发及静态氧化的方法制备了超导磁通量子比特样品.通过对Al薄膜厚度与平整度关系分析,选取60 nm作为隧道结底层Al厚度,增加蒸发源到样品衬底间的距离,提高了Al薄膜平整度,降低了隧道结漏电流.通过透射电子显微镜分析,观测到Al隧道结三层结构,并得到了势垒层厚度和氧分压的关系.As one of the candidates for realizing quantum bits, superconducting quantum bits, based on Josephson junction, have the advantages of easy integrating, coupling with the outside environment and so on. Double-layer photoresist was used to prepare suspended shadow mask by deep ultra-violet（DUV） lithography. We fabricated the sample of superconducting flux quantum bits by electron beam evaporation and static oxidization with aluminum as superconducting material. According to the dependence of the flatness on the thickness of aluminum film, we select 60 nm as the thickness of the bottom electrode of tunnel junction. By increasing the distance between the evaporation source and the substrate, we have improved the smoothness of film and thus reduced the leakage current of tunnel junction. The tri-layer structure of aluminum tunnel junction was observed by transmission electron microscopy（TEM）, and the relationship between the thickness of barrier layer and the oxidation pressure was obtained.

关 键 词：超导磁通量子比特 Al/AlOx/Al超导隧道结 静态氧化 透射电子显微镜分析 势垒层厚度 薄膜平整度 漏电比 

分 类 号：O413.1[理学—理论物理]