Molecule-Precision Cavity Formation in Molecular Layer Using Scanning Tunneling Microscope Lithography

Abstract

We have demonstrated a cavity formation with molecular precision in an ordered film of 4,4‘-biphenyl dicarboxylic acid (BDA) molecules on the Au(111) surface using scanning tunneling microscopy. The BDA molecules are removed through the injection of tunneling electrons into the molecule, which excite the vibrational mode of the BDA molecule to cleave the hydrogen bonding between carboxyl groups. The structures have molecular-scale sharp edges and can be used as cavities for the investigation of a host−guest architecture on surfaces.

Patterning of self-assembled monolayers based on differences in molecular conductance

“…To access the sub-100 nm range a number of patterning techniques based on electrons, photons, mechanical forces or electrochemical processes have been developed such as electron beam lithography (EBL) [5,6], extreme-UV interference lithography (EUV-IL) [7] and scanning probe microscopies (SPM), with the latter comprising near-field optical microscopy (SNOM) [8], scanning tunneling microscopy (STM) [9][10][11][12][13][14][15][16][17][18][19] and atomic force microscopy (AFM) [20][21][22][23][24][25]. Dip pen nanolithography (DPN) [26][27][28] as another AFM-derived technique which is not based on replacement like nanografting [20,21] but uses localized transfer of material also allows rather routine access to feature sizes below 100 nm, even in a parallelized fashion [29,30].…”

“…In the case of high tunneling current the tip penetrates the SAM, thus resulting in the mechanical displacement of molecules similar to nanoshaving/nanografting by AFM [20,21]. While SAM modification by STM was demonstrated already quite some time ago [11,16,31] this approach has, however, been relatively limited [9][10][11][12][13][14][15][16][17] as it is plagued by a lack of reproducibility due to the required strong interactions between STM tip and SAM which easily result in tip modification and quick deterioration of resolution. Therefore, STM does not seem to offer any advantage over AFM techniques with their somewhat lower resolution but the use of a more robust tip.…”