SCANNING TUNNELING MICROSCOPE TIP AS A POSITIONABLE CONTACT - PROBINGA JOSEPHSON-JUNCTION ARRAY AT SUBKELVIN TEMPERATURES

We describe an experiment in which a scanning tunneling microscope (ST M) is employed to selectively contact a lithographically fabricated st ructure at 350 mK. The STM enables us to probe the structure, a Joseph son-junction array, at various positions. The experiment demonstrates that it is possible to combine the use of a scanning tunneling microsc ope with transport measurements on lithographically fabricated structu res at temperatures below 1 K. We focus on the strategy to position th e tip above the structure of interest, the influence of the STM on the electronic noise, and on the effective temperature of the sample. (C) 1998 American Vacuum Society.