Thin layers of boron nitride could find use in flexible electronics applications, especially because the layer thickness can be controlled on the atomic scale. BN films also have excellent mechanical, thermal and mechanical properties and so could be ideal for use in optoelectronics applications and as a good support material for graphene devices thanks to the fact that the two materials have very similar lattice constants.

Rodney Ruoff’s group in Texas has now shown that it can control the number of layers of boron nitride that can be grown by varying the conditions in a CVD reactor. The researchers were able to do this by growing their films in a low pressure chemical vapour deposition chamber using diborane and ammonia gas, two commonly used precursors in industry, and by changing growth conditions such as temperature, the time the reactants spent in the growth chamber and gas partial pressure.

“Being able to control the number of layers of h-BN grown means that BN films might now be able to be used in real-world applications,” team member Ariel Ismach told nanotechweb.org. “For example, they might be employed as dielectric films in graphene-based electronic devices and in electronic devices in general that require monolayers or just a few layers of the material.”

Moreover, the sequential-growth method described in our work will help us better understand surface chemistry effects and so allow us to work out how h-BN films actually grow in the CVD reactor, he adds.

The team now plans to continue studying the BN layers it has made and will try and integrate the films into various electronic applications. “We hope to study BN growth under different conditions, on different substrates, and look at what happens when different precursors are used,” said Ismach. “We are also adding more characterization techniques to our arsenal in an effort to develop a better understanding of BN thin films and correlate the material’s structure to its optical, electronic, mechanical and thermal properties.”

The research is detailed in ACS Nano.