Fabrication of Point
Contacts by FIB Patterning
PAPER: B.
O’Gorman and M. Tsoi,
“Fabrication
of Point Contacts by FIB Patterning”,
submitted for publication
SLIDES: the March 2008 Meeting of American
Physical Society,
ABSTRACT:
We describe a new technique for the fabrication of
point contacts using a focused ion beam (FIB) patterning. After sample coverage
with a thin insulating layer (SiO), an FIB is used to
mill a 100-nm-diameter hole through the insulator. Electrical contact to the
sample is then made in-situ by filling the hole with a metal (Pt) using the ion
beam assisted chemical vapor deposition capability of our FIB system. We have
demonstrated the use of two such contacts (as an emitter and collector) in a
transverse electron focusing (TEF) experiment. The contacts were made to a
single crystal of bismuth, ballistic electrons were
injected into the crystal through the emitter contact and then focused onto the
collector by a magnetic field. We see the expected voltage peaks at the
collector as a function of the applied magnetic field. Temperature dependent
TEF measurements provided direct information about relaxation time of
conduction electrons.
We thank V. S. Tsoi for valuable comments
and for providing the Bi single crystals. The work was supported in part by NSF
Grant No. DMR-06-45377. Point contacts were fabricated
using the facilities of the Center for Nano and
Molecular Science and Technology at UT