Computational Study on the Performance Comparison of Monolayer and Bilayer Zigzag Graphene Nanoribbon FETs

In our ab initio study on the device performance of nitrogen-doped monolayer zigzag GNR (ZGNR) FETs, an increase in ZGNR width from 0.92 nm to 1.78 nm degrades the I
_max
|I
_min
ratio due to the decrease in the energy bandgap (Eg) which causes the I
_min
to increase. It is also observed that the presence of vacancy at the edges of the channel ribbon can also open up an Eg in ZGNRs as nitrogen dopants, and the performance of such device depends greatly on the vacancy concentration. In addition, simulation was carried out on the nitrogen-doped bilayer ZGNR FET and comparing to the monolayer ZGNR FET, the bilayer device provides a larger current while the I
_max
|I
_min
is lowered.