Nanofriction characteristics of h-BN with electric field induced electrostatic interaction

The nanofriction properties of hexagonal boron nitride(h-BN)are vital for its application as a substrate for graphene devices and solid lubricants in micro-and nano-electromechanical devices.In this work,the nanofriction characteristics of h-BN on Si/SiO_(2) substrates with a bias voltage are explored using a conductive atomic force microscopy(AFM)tip sliding on the h-BN surface under different substrate bias voltages.The results show that the nanofriction on h-BN increases with an increase in the applied bias difference(V_(t–s))between the conductive tip and the substrate.The nanofriction under negative V_(t–s) is larger than that under positive V_(t–s).The variation in nanofriction is relevant to the electrostatic interaction caused by the charging effect.The electrostatic force between opposite charges localized on the conductive tip and at the SiO2/Si interface increases with an increase in V_(t–s).Owing to the characteristics of p-type silicon,a positive V_(t–s) will first cause depletion of majority carriers,which results in a difference of nanofriction under positive and negative V_(t–s).Our findings provide an approach for manipulating the nanofriction of 2D insulating material surfaces through an applied electric field,and are helpful for designing a substrate for graphene devices.