'Nobody knows yet which horse will win the race as there are a few proposals for graphene-based electronic devices,' says Antonio Castro Neto, a graphene expert at the National University of Singapore. 'This is a very promising one. It proves what we have been saying for quite sometime, namely that graphene alone will have limited impact in electronics but when it is combined with other two-dimensional crystals, such as BN, the possibilities are only limited by our own imagination.'
Last Friday we covered the smart scientists at MIT using molybdenum disulphide as competition to graphene, due to graphene’s lack of a bandgap. They explained:
The lack of a bandgap, means that with a switch made of graphene, “you can turn it on, but you can’t turn it off. That means you can’t do digital logic.” So people have for years been searching for a material that shares some of graphene’s extraordinary properties, but also has this missing quality — as molybdenum disulfide does.”
Anything Massachusetts’s MIT can do, we can do better, say the researchers at New York’s Cornell University, who have stuck graphene to boron nitride, promptly overcoming graphene’s lack of a band gap. Cornell’s process produces an advantageous “heterojunction” at the interface. “Heterojunctions are the interfaces between two materials that have different electronic properties and are the building blocks of most semiconducting electronic devices including transistors, solar cells and integrated circuits,” they write.
Time will tell which competing method ultimately proves best, but I suspect that unless one has a significant cost or performance advantage over the other, both competing horses are likely to be put to use. It’s increasingly hard to keep up with all the new developments, which are about to change our new 21st century Carbon Age.
Graphene–boron nitride stitching to sew up electronics
29 August 2012
The race to create ultrathin, transparent and flexible electronic devices using graphene – the most conductive material known to exist – has a promising new contender. Researchers in the US have developed a process that stitches atom-thick sheets of insulating boron nitride to graphene and this could prove to be a versatile and scalable method for creating atomically thin integrated circuits.
Graphene is a single layer of carbon atoms arranged in a hexagonal lattice and touted as a replacement for silicon in electronic devices. However, graphene lacks a band gap – meaning that it cannot stop conducting electricity. This poses a problem for controlling the flow of electrons through the material, which is a requirement for any electronic device. Several research groups are working on ways to make hybrid graphene materials suitable for devices, but the race is still on.
Now, researchers at Cornell University in the US have developed a process called ‘patterned re-growth’ that stitches together graphene with atom-thick sheets of boron nitride – also arranged in a hexagonal lattice – to produce a two dimensional hybrid material with complementary properties.
—- The two different regions can be laterally stitched together very well, forming mechanically stable atomic films,' says Cheol-Joo Kim, a co-author of the study. 'This means they are not just locally close to each other but they also form a heterojunction, opening possibilities to utilise interesting properties of the junction.'
Heterojunctions are the interfaces between two materials that have different electronic properties and are the building blocks of most semiconducting electronic devices including transistors, solar cells and integrated circuits.