Patterning Mesoscale Gradient Structures with Self-Assembled Monolayers and Scanning Tunneling Microscopy Based Replacement Lithography

Abstract

Complex mesostructures showing gradient‐type surface coverage with ω‐substituted alkanthiols can be generated by STM replacement lithography. Variations of the replacement bias, lithographic scan rate, or raster line spacing create the gradient. The Figure (see also front cover) shows an L‐shaped gradient structure where Au(111) is separately thiol‐covered in the corner, and highly covered on both ends.

Au–Pd Alloy Gradients Prepared by Laterally Controlled Template Synthesis

“…Preparation of materials displaying gradients of properties (morphology, [1][2][3] composition, [3][4][5][6][7][8][9][10][11][12] reactivity, [13] porosity, [14] density, [15,16] etc.) is potentially important for obtaining unusual materials, which can be used as sensors, [17] catalysts, [13] or in other applications requiring spatially varying properties of the material.…”

Tip-Induced Modification of Polyoxometalate-Dodecane Thiol Self-Assembled Monolayers on Au(111) during Scanning Tunneling Microscopy Imaging

“…3,4 Specifically, STM tips under very negative tip bias voltages (tip-to-surface electron tunneling) around −3 V remove thiolates underneath them in vacuum 5,6 as well as in nonpolar solvents, [7][8][9] which allow for further wet etching and replacement with other thiolates, respectively. The tipinduced desorption depends on various experimental parameters such as tip bias voltage, tunneling current, and potential applied at Au substrates.…”

Patterning of Chemical Gradients with Submicrometer Resolution Using Edge‐Spreading Lithography

“…[1] The methodology of patterning surface gradients can vary depending on the materials involved and the resolution to be achieved. [2][3][4][5][6][7][8][9][10][11][12] Self-assembled monolayers (SAMs) -ordered and dense layers of molecules adsorbed on a surface -are exquisite systems for introducing functionality to substrates in a chemically defined way and are thus well suited for gradient fabrication. For example, Chaudhury and Whitesides have prepared macroscopic-gradient SAMs on silicon substrates by controlling the diffusion of an alkyltrichlorosilane through the vapor phase.…”

“…One solution was demonstrated by Gorman and co-workers using replacement lithography mediated by a scanning tunneling microscope. [12] In this paper, we describe a simple and flexible approach for patterning gradient SAMs of alkanethiols on gold substrates using the technique of edge-spreading lithography (ESL). [13] In contrast to most other techniques, a multitude of gradient features can be patterned on the same substrate in a parallel fashion while providing both control over the composition of the gradients and high resolution.…”