Semiconductors, such as silicon, have revolutionized the world of technology, powering our smartphones, computers, and countless electronic devices. However, these ubiquitous materials have their limitations. The atomic vibrations in semiconductors, known as phonons, cause the particles carrying energy and information, like electrons or electron-hole pairs called excitons, to scatter and lose energy. This results in slower information transfer and increased heat generation.
In the quest for more efficient alternatives, a team of chemists at Columbia University, led by Ph.D. student Jack Tulyag and chemistry professor Milan Delor, has pioneered a groundbreaking semiconductor material known as Re6Se8Cl2. This superatomic material offers a solution to the phonon scattering problem by harnessing a unique property called ballistic, or scatter-free, flow.
Unlike traditional semiconductors, Re6Se8Cl2 allows excitons to bind with phonons, creating new quasiparticles called acoustic exciton-polarons. These quasiparticles exhibit sluggish movement, akin to the tortoise in the classic fable. However, this deliberate pace allows them to pair up with equally slow-moving acoustic phonons, enabling them to advance gradually and steadily. Unimpeded by other phonons, acoustic exciton-polarons in Re6Se8Cl2 ultimately outpace electrons in silicon, moving twice as fast and covering several microns in less than a nanosecond.
The potential of Re6Se8Cl2 goes beyond speed. With polarons capable of lasting up to 11 nanoseconds, theoretical devices utilizing these quasiparticles could achieve processing speeds in the realm of femtoseconds—six magnitudes faster than current electronics. Importantly, this breakthrough can be achieved at room temperature, highlighting its practical viability.
Re6Se8Cl2 represents a new class of materials known as superatomic semiconductors, synthesized by binding clusters of atoms together. These superatoms possess distinct properties compared to their constituent elements and are a subject of intense research at Columbia’s Material Research Science and Engineering Center. By fine-tuning the transport of energy in superatoms, scientists aim to unlock the full potential of these materials in various technological applications.
The exciting advancements achieved with Re6Se8Cl2 demonstrate that the search for optimal semiconductors is far from over. By exploring novel materials and harnessing quantum phenomena, researchers continue to push the boundaries of what is possible, paving the way for faster, more efficient electronic devices that will shape the future of technology.
What are phonons?
Phonons are quantum particles that result from the vibrations of the atomic structure in a material. They interact with particles carrying energy and information, causing them to scatter and lose energy.
How does Re6Se8Cl2 overcome phonon scattering?
In Re6Se8Cl2, excitons bind with acoustic phonons to create acoustic exciton-polarons. These quasiparticles advance slowly but steadily by pairing with slow-moving phonons, allowing them to avoid scattering and achieve faster movement compared to electrons in traditional semiconductors.
What are superatomic semiconductors?
Superatomic semiconductors are materials formed by clustering atoms together to behave as one “superatom.” These materials possess unique properties that differ from their constituent elements, making them promising candidates for advanced technological applications.
What are the potential advantages of Re6Se8Cl2 in future devices?
Re6Se8Cl2’s ballistic flow properties offer the potential for faster and more efficient electronic devices. The use of acoustic exciton-polarons could lead to processing speeds in the femtosecond range, significantly faster than current technologies, without the need for specialized cooling methods.