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MIT reports semiconductors’ pounds,” says Rafael Jaramillo, the Thom-
giant response to light as Lord Associate Professor of Materials
Science and Engineering at MIT and leader
CAMBRIDGE, Mass. — In an example of the team.
of the adage “everything old is new
again,” MIT engineers report a new Elastic response
discovery in semiconductors, well-
known materials that have been the Says Ju Li, another MIT professor involved
focus of intense study for over 100 in the work, “to see defects having such
years thanks to their many applica- big effects on elastic response is very sur-
tions in electronic devices. prising, which opens the door to a variety
of applications. Computation could help us
Light makes chips stiffer screen many more such materials.”
The team found that these important ma-
terials not only become much stiffer in re- Li is the Battelle Energy Alliance Professor
sponse to light, but the effect is reversible in Nuclear Science and Engineering (NSE)
when the light is turned off. with a joint appointment in the Depart-
ment of Materials Science and Engineering
(DMSE). Both Jaramillo and Li are also af-
filiated with the Materials Research Labo-
ratory.
The work is reported in a recent issue
of Physical Review Letters. The result-
ing paper was highlighted as an Editors’
Suggestion. It is also the focus of an ac-
companying synopsis for Physics Magazine
titled “Semiconductors in the Spotlight,” by
Sophia Chen.
Jaramillo remembers being intrigued by
a 2018 paper in Science showing how a
MIT graduate student Jiahao Dong with the nanoindentation ma- semiconductor made of zinc sulfide be-
chine used in recent MIT work on the response of semiconductors
to light. (Photo: Elizabeth Thomson) comes more brittle when exposed to light.
The engineers also explain what is hap-
pening at the atomic scale, and show how “Behaved like a cracker”
the effect can be tuned by making the “When [the researchers] shone light on
materials in a certain way — introducing it, it behaved like a cracker. It snapped.
specific defects — and using different col- When they turned off the light, it behaved
ors and intensities of light. more like a gummy bear, where it could be
squeezed without breaking into pieces.”
New scientific direction
“We’re excited about these results because Why? Jaramillo and colleagues decided to
we’ve uncovered a new scientific direc- find out.
tion in an otherwise very well-trod field. In
addition, we found that the phenomenon Along the way, the team not only repro-
may be present in many other com- duced the Science work, but also showed
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