Scientists at the University of Washington have developed what they believe is the thinnest-possible semiconductor, a new class of nanoscale materials made in sheets only three atoms thick. Two of these single-layer semiconductor materials can be connected in an atomically seamless fashion known as a heterojunction. A heterojunction is the interface that occurs between two layers or regions of dissimilar crystalline semiconductors, both of which have unequal band gaps. This result could be the basis for next-generation flexible and transparent computing, better light-emitting diodes (LEDs), and solar technologies.
Collaborators from the electron microscopy center at the University of Warwick in England found that all the atoms in both materials formed a single honeycomb lattice structure, without any distortions or discontinuities. This provides the strongest possible link between two single-layer materials, necessary for flexible devices. Within the same family of materials it is feasible that researchers could bond other pairs together in the same way.
According to the researchers, the technique is scalable. With a larger furnace, it would be possible to mass-produce sheets of these semiconductor heterostructures. On a small scale, it takes about five minutes to grow the crystals, with up to two hours of heating and cooling time. It is quite possible that in the future it may be possible to combine two-dimensional materials using this technique to form all kinds of electronic structures such as in-plane quantum wells and quantum wires, superlattices, fully functioning transistors, and even complete electronic circuits.
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