title: Nanoparticles assume electrical potential according to substrate, size, and surface termination.
abstract: Electrical potential of nanoparticles under relevant environment is substantial for their applications in electronics as well as sensors and biology. Here, we use Kelvin force microscopy to characterize electrical properties of semiconducting diamond nanoparticles (DNPs) of 5-10 nm nominal size and metallic gold nanoparticles (20 and 40 nm) on Si and Au substrates under ambient conditions. The DNPs are deposited on Si and Au substrates from dispersions with well-defined zeta-potential. We show that the nanoparticle potential depends on its size and that the only reliable potential characteristic is a linear fit of this dependence within a 5-50 nm range. Systematically different potentials of hydrogenated, oxidized, and graphitized DNPs are resolved using this methodology. The differences are within 50 mV, that is much lower than on monocrystalline diamond. Furthermore, all of the nanoparticles assume their potential within -60 mV according to the Au and Si substrate, thus gaining up to 0.4 V difference. This effect is attributed to DNP charging by charge transfer and/or polarization. This is confirmed by secondary electron emission. Such effects are general with broad implications for nanoparticles applications.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00, Prague 6, Czech Republic. stehlik@fzu.cz
authors.forename: Stepan
authors.initials: S
authors.lastname: Stehlik
authors.forename: Tristan
authors.initials: T
authors.lastname: Petit
authors.forename: Hugues A
authors.initials: HA
authors.lastname: Girard
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Arnault
authors.forename: Alexander
authors.initials: A
authors.lastname: Kromka
authors.forename: Bohuslav
authors.initials: B
authors.lastname: Rezek
mesh_terms: D004558:Electric Stimulation; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties
chemical_list: D006046:Gold