Topography of the two-dimensional crystal on top of the microscopically small wire indicated by dashed lines. Excitons freely move along the wire-induced dent, but cannot escape it in the perpendicular direction. (Courtesy: Florian Dirnberger)
Topics: Applied Physics, Condensed Matter Physics, Electrical Engineering
Using a technique known as strain engineering, researchers in the US and Germany have constructed an “excitonic wire” – a one-dimensional channel through which electron-hole pairs (excitons) can flow in a two-dimensional semiconductor like water through a pipe. The work could aid the development of a new generation of transistor-like devices.
In the study, a team led by Vinod Menon at the City College of New York (CCNY) Center for Discovery and Innovation and Alexey Chernikov at the Dresden University of Technology and the University of Regensburg in Germany deposited atomically thin 2D crystals of tungsten diselenide (fully encapsulated in another 2D material, hexagonal boride nitride) atop a 100 nm-thin nanowire. The presence of the nanowire created a small, elongated dent in the tungsten diselenide by slightly pulling apart the atoms in the 2D material and so inducing strain in it. According to the study’s lead authors, Florian Dimberger and Jonas Ziegler, this dent behaves for excitons much like a pipe does for water. Once trapped inside, they explain, the excitons are bound to move along the pipe.
Strain guides the flow of excitons in 2D materials, Isabelle Dumé, Physics World