Measuring a tiny quasiparticle is a major step forward for semiconductor technology

Date:
June 19, 2020
Source:
Rensselaer Polytechnic Institute
Summary:
A team of researchers has uncovered new information about the mass
of individual components that make up a promising quasiparticle,
known as an exciton, that could play a critical role in future
applications for quantum computing, improved memory storage,
and more efficient energy conversion.



FULL STORY ==========================================================================
A team of researchers led by Sufei Shi, an assistant professor of chemical
and biological engineering at Rensselaer Polytechnic Institute, has
uncovered new information about the mass of individual components that
make up a promising quasiparticle, known as an exciton, that could play
a critical role in future applications for quantum computing, improved
memory storage, and more efficient energy conversion.


========================================================================== Published today in Nature Communications, the team's work brings
researchers one step closer to advancing the development of semiconductor devices by deepening their understanding of an atomically thin class of materials known as transitional metal dichalcogenides (TMDCs), which have
been eyed for their electronic and optical properties. Researchers still
have a lot to learn about the exciton before TMDCs can successfully be
used in technological devices.

Shi and his team have become leaders in that pursuit, developing and
studying TMDCs, and the exciton in particular. Excitons are typically
generated by energy from light and form when a negatively charged electron bonds with a positively charged hole particle.

The Rensselaer team found that within this atomically thin semiconductor material, the interaction between electrons and holes can be so strong
that the two particles within an exciton can bond with a third electron
or hole particle to form a trion.

In this new study, Shi's team was able to manipulate the TMDCs material
so the crystalline lattice within would vibrate, creating another
type of quasiparticle known as a phonon, which will strongly interact
with a trion. The researchers then placed the material within a high
magnetic field, analyzed the light emitted from the TMDCs from the
phonon interaction, and were able to determine the effective mass of
the electron and hole individually.

Researchers previously assumed there would be symmetry in mass, but,
Shi said, the Rensselaer team found these measurements were significantly different.

"We have developed a lot of knowledge about TMDCs now," Shi said. "But in
order to design an electronic or optoelectronic device, it is essential
to know the effective mass of the electrons and holes. This work is one
solid step toward that goal."

========================================================================== Story Source: Materials provided by
Rensselaer_Polytechnic_Institute. Original written by Torie Wells. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zhipeng Li, Tianmeng Wang, Shengnan Miao, Yunmei Li, Zhenguang Lu,
Chenhao Jin, Zhen Lian, Yuze Meng, Mark Blei, Takashi Taniguchi,
Kenji Watanabe, Sefaattin Tongay, Wang Yao, Dmitry Smirnov,
Chuanwei Zhang, Su- Fei Shi. Phonon-exciton Interactions in WSe2
under a quantizing magnetic field. Nature Communications, 2020;
11 (1) DOI: 10.1038/s41467-020-16934- x ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200619115716.htm

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