An international research team involving Skoltech (VEB.RF group) scientists has developed a method for creating one-dimensional quantum wires in structures made of two different two-dimensional materials – molybdenum diselenide and tungsten diselenide. The technology is based on stretching the layers, which changes the relative arrangement of atoms between the layers and, with it, the electronic and optical properties. This allows the material’s behavior to be tuned without chemical additives or complex processing. Such an approach could form the basis for flexible electronics and devices that respond to pressure, bending, or stretching. The research results are published in Physical Review Letters.
These two-dimensional materials are only three atoms thick. When two such materials are joined at a slight angle, the atoms at the contact point form a regular pattern: regions with more favorable and less favorable atomic arrangements alternate. If the structure is then stretched in one direction, the pattern changes. Instead of triangular regions, long parallel stripes appear, separated by narrow gaps ranging from 3 to 15 nanometers wide. Quantum potential wells arise in these gaps, trapping electron-hole pairs – excitons – inside a narrow line. This is how a quantum wire is formed.
To observe the structure before and after deformation, the scientists used two imaging methods. First, they observed the pattern using torsional atomic force microscopy. Then they transferred the sample onto a substrate with parallel protrusions. The protrusions created local stretching of about 0.1 %, which proved sufficient to rearrange the pattern from two-dimensional to one-dimensional, as confirmed by scanning electron microscopy. As a result, excitons in the one-dimensional channels began to emit light with linear polarization oriented along the channels, achieving a polarization degree of up to 0.9.
Anvar Baimuratov, who led the theoretical part of the study, Associate Professor at the Skoltech Engineering Physics Center and head of the Two-Dimensional Materials Theory Group, commented: “We have shown that stretching makes it possible to switch the structure from a two-dimensional configuration to a one-dimensional one. This allows us to control the energy, lifetime, and polarization of the emission by choosing the initial twist angle between the layers and by adjusting the substrate profile to control deformation at the nanoscale. Such a degree of control is essential for creating quantum devices with directional and tunable emission.”
The results open up the possibility of creating one-dimensional quantum wires with tailored properties for applications in optoelectronics, quantum sensors, and quantum information processing elements.