"This is only the first instance showing that these structures can indeed be grown in 2-D like graphene," Ajayan said. "I think the whole new field will be exciting for basic physics and electro-optical applications."
Graphene has been the subject of intense study in recent years for its high conductivity and the possibility of manipulating it on scales that go well below the theoretical limits for silicon circuitry. A layer of graphene is a hexagonal lattice of carbon atoms. In bulk, it's called graphite, the stuff of pencil lead. Graphene was first isolated in 2004 by British scientists who used Scotch tape to pull single-atom layers from graphite.
"Graphene is a very hot material right now," said Song, who had teamed with Ci to investigate doping graphene with various materials to determine its semiconducting properties. Knowing that both boron and nitrogen had already been used in doping bulk graphite, they decided to try cooking it via CVD onto a copper base.
Structurally, h-BN is the same as graphene, a hexagon-shaped lattice of carbon atoms that looks like chicken wire. Ci and Song found that through CVD, graphene and h-BN merged into a single atomic sheet, with pools of h-BN breaking up the carbon matrix.
The critical factor for electronic materials is the band gap, which must be tuned in a controlled manner for applications. Graphene is a zero-gap material, but ways have been proposed to tailor this gap by patterning it into nanoscale strips and doping it with other elements.
Ci and Song took a different approach through CVD, controlling the ratio of carbon to h-BN over a large, useful range.
It remains challenging to produce single layers of the hybrid material, as most lab-grown films contain two or three layers. The researchers also cannot yet control the placement of h-BN pools in a single sheet or the rotational angles between layers but they're working on it.
In fact, having multiple laye
|Contact: David Ruth|