Stacking up cleanliness in two-dimensional materials

One of the most interesting areas of research into two-dimensional materials is how they behave when they are stacked together.

The best known of these materials is graphene, but since its isolation at Manchester University in 2004, a wide variety of other 2D materials has also been discovered.

Many of these have unusual properties to do with the way electrons behave on their surfaces, and these properties become especially interesting when different materials are stacked together face-to-face.

Known as heterostructures, these stacks can be fine tuned to act as components such as LEDs, high-speed electronics, and even water purification devices.

However, the properties of these devices depends on the junction between two materials being clean. It had been assumed in the early days of heterostructure research that most materials in this class exhibit a self-cleaning phenomenon; when they are put into contact, any impurities, such as atoms and molecules in the air, are simply squeezed out. But new research at Manchester University suggests that this is not the case.