title: Anomalous response of supported few-layer hexagonal boron nitride to DC electric fields: a confined water effect?
abstract: We use electric force microscopy (EFM) to study the response of supported few-layer hexagonal boron nitride (h-BN) to an electric field applied by the EFM tip. Our results show an anomalous behavior in the dielectric response of h-BN atop Si oxide for different bias polarities: for a positive bias applied to the tip, h-BN layers respond with a larger dielectric constant than the dielectric constant of the substrate, while for a negative bias, the h-BN dielectric constant appears to be smaller. Based on ab initio calculations, we propose that this behavior is due to a water layer confined between the Si oxide substrate and h-BN layers. This hypothesis was experimentally confirmed by sample annealing and also by a comparative analysis with h-BN on a non-polar substrate.
authors.affiliation: Departamento de Física, ICEx, Universidade Federal de Minas Gerais-UFMG, CP 702, 30123-970 Belo Horizonte, Brazil.
authors.forename: C K
authors.initials: CK
authors.lastname: Oliveira
authors.forename: M J S
authors.initials: MJ
authors.lastname: Matos
authors.forename: M S C
authors.initials: MS
authors.lastname: Mazzoni
authors.forename: H
authors.initials: H
authors.lastname: Chacham
authors.forename: B R A
authors.initials: BR
authors.lastname: Neves