Ulsan National Institute of Science and Technology(UNIST) researchers in Korea have announced a method for mass production of graphene-based field-effect transistors (FETs).
The design creates boron/nitrogen co-doped graphene nanoplatelets (BCN-graphene) via a simple solvothermalreaction of BBr3/CCl4/N2 in the presence of potassium.
Various methods of making graphene-based FETs have been exploited, including doping graphene, tailoring graphene like a nanoribbon, and using boron nitride as a support, the researchers said. Among the methods of controlling the bandgap* of graphene, doping methods show the most promise in terms of industrial-scale feasibility, they suggest.
Researchers have previously tried to add boron to graphene to open its bandgap to achieve semiconductor performance, without success, because the atomic size of boron, 85 pm (atomic radius) is larger than that of carbon (77 pm).
Now, the UNIST researcher team, led by Prof. Jong-Beom Baek, has found that boron/nitrogen co-doping is only feasible when carbon tetrachloride (CCl4 ) is treated with boron tribromide (BBr3 ) and nitrogen (N2) gas, which at 70 pm is a bit smaller than carbon and boron.
Pairing two nitrogen atoms and two boron atoms can compensate for the atomic size mismatch, so boron and nitrogen pairs can be easily introduced into the graphitic network, the researchers say. The resultant BCN-graphene generates a bandgap appropriate for FETs.
“Although the performance of the FET is not in the range of commercial silicon-based semiconductors, this initiative work should be the proof of a new concept and a great leap forward for studying graphene with bandgap opening,” said Baek. “Now, the remaining challenge is fine-tuning a bandgap to improve the on/off current ratio for real device applications.”