Title :
HTS scanning SQUID microscopy of active circuits
Author :
Fleet, E.F. ; Chatraphorn, S. ; Wellstood, F.C. ; Knauss, L.A.
Author_Institution :
Center for Supercond. Res., Maryland Univ., College Park, MD, USA
fDate :
6/1/1999 12:00:00 AM
Abstract :
We have used a high-T/sub c/ scanning SQUID microscope to image semiconductor circuits operating in air at room temperature. Our microscope uses a commercially available 77 K refrigerator to cool a YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// dc SQUID. The system maintains vacuum isolation of the SQUID even when it is separated from a room-temperature sample by about 30 /spl mu/m. When operated in this manner, the SQUID has a magnetic field sensitivity of 20 pT//spl radic/Hz above 500 Hz. By inverting the magnetic field images to generate two-dimensional current density distributions, we localize current paths to within /spl plusmn/36 /spl mu/m at SQUID-sample separations of 150 /spl mu/m. We present images and discuss the spatial resolution obtained with this technique.
Keywords :
SQUID magnetometers; barium compounds; high-temperature superconductors; integrated circuit testing; microscopy; yttrium compounds; 77 K; HTS scanning SQUID microscopy; YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// DC SQUID; YBa/sub 2/Cu/sub 3/O/sub 7/; magnetic field imaging; semiconductor active circuit; spatial resolution; two-dimensional current density distribution; vacuum isolation; Active circuits; Current density; High temperature superconductors; Image generation; Magnetic fields; Microscopy; Refrigeration; SQUIDs; Spatial resolution; Vacuum systems;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
