Adsorption/desorption and electrically controlled flipping of ammonia molecules on graphene

In this paper, we evaluate the adsorption/desorption of ammonia molecules on a graphene surface by studying the Fermi level shift. On the basis of a physically plausible model, the adsorption and desorption rates of ammonia molecules on graphene have been extracted from the measured Fermi level shift as a function of exposure time. An electric-field-induced flipping behavior of the ammonia molecules on graphene is suggested based on field effect transistor (FET) measurements.