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1993-05-03
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PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. (818) 354-5011
FOR IMMEDIATE RELEASEMay 1, 1989
Physicists at the Jet Propulsion Laboratory have
developed a new technique that allows them to "see" how electrons
behave in a structure, and their invention may do for the science
of electronic devices what the early microscope did for biology.
The technique is called ballistic-electron-emission
microscopy (BEEM) and for the first time it enables scientists to
see below the surface of a structure to a semiconductor interface
and discover what happens when electrons pass through that
boundary. BEEM allows for nanometer-resolution imaging which
enables scientists to look at a region that covers only 20 atoms.
Using BEEM, scientists can identify microscopic defects that
occur at a subsurface level.
"We apply BEEM as a diagnostic tool to look at
semiconductors and to understand defect formation and then
develop fabrication techniques for the production of defect-free
devices," said Dr. William Kaiser, a JPL solid-state physicist
who helped pioneer the technique with Dr. L. Douglas Bell and Dr.
Michael H. Hecht.
BEEM uses the scanning tunneling microscope (STM) to
inject a highly localized electron current into a device
structure. In recent experiments the JPL group used BEEM to look
at the interface between gold and gallium arsenide. With BEEM,
scientists saw reactions take place that they hadn't known about
before. They observed that gallium arsenide actually decomposed
and reacted with gold when an electric current was passed through
the semiconductor. "For the first time we can understand what
affects electron transport through interfaces. It allows us to
do things we've never done before," Kaiser said.
BEEM is revolutionary because it gives scientists the
tool to see the fundamental properties of a structure that they
couldn't measure and couldn't see before, the team noted.
"One of our goals is to understand the development of
the electronic properties of a material one atomic layer at a
time," Kaiser said.
Ultimately, BEEM will lead to better transistors and
detectors and the development of high-speed, reliable, space-
qualified microelectronics that can be used on future space
probes.
BEEM is a development of JPL's Center for Space
Microelectronics Technology (CSMT) and is sponsored by the
Innovative Science and Technology Office of the Strategic Defense
Initiative Organization and the Office of Naval Research.
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#1238 5/1/89 mah