Researchers from Penn State University have worked with University of Texas at Dallas engineers to induce different two-dimensional materials to form directly on top of one another. The stacking approach achieves clean interfaces between layers — an important factor for novel nanoelectronic circuits.

The Penn State scientists have made two-dimensional, or monolayer, materials by combining a variety of elements, such as tungsten or molybdenum with sulfur, gallium or silicon with selenium, and boron with nitrogen.

Improved techniques for studying 2D materials have made it easier to predict which compounds will form monolayers and how they might behave in that form. Like graphene, the two-dimensional materials exhibit properties not seen in their three-dimensional forms. Several materials — such as molybdenum disulfide, tungsten disulfide, and a form of boron nitride — are semiconductors that could enable new ultra-small electronics.

Other materials are photoluminescent, absorbing light of one wavelength and sending the energy back out at another wavelength. The resulting photoluminescent capability could become the basis for a new generation of devices that detect or emit light.