Tip induced mechanical deformation of epitaxial graphene grown on reconstructed 6H–SiC(0001) surface during scanning tunneling and atomic force microscopy studies

Abstract

The structural and mechanical properties of an epitaxial graphene (EG) monolayer thermally grown on top of a 6H-SiC(0001) surface were studied by combined dynamic scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM). Experimental STM, dynamic STM and AFM images of EG on 6H-SiC(0001) show a lattice with a 1.9 nm period corresponding to the (6 × 6) quasi-cell of the SiC surface. The corrugation amplitude of this (6 × 6) quasi-cell, measured from AFM topographies, increases with the setpoint value of the frequency shift Δf (15-20 Hz, repulsive interaction). Excitation variations map obtained simultaneously with the AFM topography shows that larger dissipation values are measured in between the topographical bumps of the (6 × 6) quasi-cell. These results demonstrate that the AFM tip deforms the graphene monolayer. During recording in dynamic STM mode, a frequency shift (Δf) map is obtained in which Δf values range from 41 to 47 Hz (repulsive interaction). As a result, we deduced that the STM tip, also, provokes local mechanical distortions of the graphene monolayer. The origin of these tip-induced distortions is discussed in terms of electronic and mechanical properties of EG on 6H-SiC(0001).

Pressure-induced commensurate stacking of graphene on boron nitride

“…Here we demonstrate a path towards achieving control over this degree of freedom by demonstrating that pressure exerted by a scanning tunneling microscopy (STM) tip [16][17][18][19][20] is capable of compressing or relaxing the interlayer separation locally between graphene and hBN. We also show that by modulating the interlayer separation we can control the degree of local commensurate stacking and the in-plane strain of graphene.…”

Determination of the STM tip-graphene repulsive forces by comparative STM and AFM measurements on suspended graphene

“…13,14 Similarly, mechanical distortions of suspended graphene can be provoked also in the repulsive force regime of the STM tip-graphene interaction. [15][16][17] Here we show that graphene bubbles formed on flat gold nanoislands can be squeezed by STM imaging in the repulsive force regime, and also that graphene suspended over gold nanovoids can be deflected by the STM tip. Comparing the STM-induced deflections to the deflections induced by AFM nanoindentation experiments we were able to quantify the repulsive forces of the STM tip-graphene interaction.…”

Reverse electrochemical etching method for fabricating ultra-sharp platinum/iridium tips for combined scanning tunneling microscope/atomic force microscope based on a quartz tuning fork

“…Interestingly, the mean tunneling current map exhibits some bright spots probably related to local variations of the density of states near the Fermi level which are not related to features in the corresponding AFM topography. This will be discussed in a forthcoming paper [44]. …”