A research team has developed a method to convert ordinary semiconducting material into quantum machines, superthin devices marked by extraordinary electronic behavior. Such an advancement could help to revolutionise a number of industries aiming for energy-efficient electronic systems.
The study describing the method, which stacks together 2D layers of tungsten disulfide and tungsten diselenide to create an intricately patterned material, or superlattice, was published online recently in the journal Nature.
“This is an amazing discovery because we didn’t think of these semiconducting materials as strongly interacting,” said Feng Wang, a condensed matter physicist with Berkeley Lab’s Materials Sciences Division and professor of physics at UC Berkeley. “Now this work has brought these seemingly ordinary semiconductors into the quantum materials space.”
Two-dimensional (2D) materials, which are just one atom thick, are like nanosized building blocks that can be stacked arbitrarily to form tiny devices. When the lattices of two 2D materials are similar and well-aligned, a repeating pattern called a moiré superlattice can form.
For the past decade, researchers have been studying ways to combine different 2D materials, often starting with graphene, a material known for its ability to efficiently conduct heat and electricity. Out of this body of work, other researchers had discovered that moiré superlattices formed with graphene exhibit exotic physics such as superconductivity when the layers are aligned at just the right angle.
The new study, led by Wang, used 2D samples of semiconducting materials, tungsten disulfide and tungsten diselenide, to show that the twist angle between layers provides a “tuning knob” to turn a 2D semiconducting system into an exotic quantum material with highly interacting electrons.
The researchers’ next plan is to measure how this new quantum system could be applied to optoelectronics, which relates to the use of light in electronics; valleytronics, a field that could extend the limits of Moore’s law by miniaturizing electronic components; and superconductivity, which would allow electrons to flow in devices with virtually no resistance.
Also contributing to the study were researchers from Arizona State University and the National Institute for Materials Science in Japan.
The work was supported by the DOE Office of Science. Additional funding was provided by the National Science Foundation, the Department of Defense, and the Elemental Strategy Initiative conducted by MEXT, Japan, and JSPS KAKENHI. The Molecular Foundry is a DOE Office of Science user facility.