Neomi Lewis ‘21

The field of economics is constantly making strides to better manipulate and strategically implement properties of charged particles. Charged particles play instrumental roles in devising electronic devices. Most particles that are commonly used, however, only retain one property that can be manipulated. Researchers from Duke University now have reason to believe that “trions,” a quasiparticle, can also be controlled in useful ways.

Trions are packets of energy, electric charge, and spin that move around inside semiconductors. As the name suggests, they carry all three properties at once, which is not a common property in other particles. Electrons or holes can carry electric charge, and excitons carry light energy but none of these particles can carry all three at once. “The reason why people are excited about trions is because they are a new way to manipulate spin, charge, and the energy of absorbed light, all simultaneously,” explains William R. Kenan.

The significance of this group’s research is that the creation and control of these particles is starting to become more feasible. Previously, trions were only found in semiconductors at extremely low temperatures (around 2 Kelvin, or -271 Celsius). It was only recently that trions were observed at room temperature in carbon nanotubes.

The team at Duke used a laser probing technique to study how trions behave in controlled and uniform carbon nanotubes. It was found that under certain conditions, trions were relatiively easy to create and control. In addition, the group was able to observe basic properties of the particles including how they are formed, their speeds and their lifespans.

 

“We found these particles are very stable in materials like carbon nanotubes, which can be used in a new generation of electronics,” claimed Bai. “This study is the first step in understanding how we might take advantage of their unique properties.” The possibilities seem to range from applications in photovoltaics, photodetectors, or in spintronics — a truly broad array for a single type of quasiparticle.

References

1. Y. Bai, et. al., Dynamics of charged excitons in electronically and morphologically homogeneous single-walled carbon nanotubes, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1712971115
2. Image retrieved from: https://turingchurch.net/down-in-the-fractal-depths-of-quantum-matter-and-space-time-fe0c83b3516