Molecular Patterning and Directed Self-Assembly of Gold Nanoparticles on GaAs

TL;DR

This paper demonstrates precise patterning of thiol molecular monolayers on GaAs surfaces and their use as templates for directed self-assembly of gold nanoparticles, advancing nano-fabrication techniques.

Contribution

It introduces a novel method combining dip-pen nanolithography and micro-contact printing for patterning on GaAs and shows controlled gold nanoparticle assembly on these templates.

Findings

Successful patterning of thiol SAMs on GaAs surface.

Directed self-assembly of gold nanoparticles achieved.

Surface diffusion models accurately predict molecular diffusion behavior.

Abstract

The ability to create micro/nano patterns of organic self-assembled monolayers on semiconductor surfaces is crucial for fundamental studies and applications in a number of emerging fields in nanoscience. Here, we demonstrate the patterning of thiol molecular SAMs on oxide-free GaAs surface by dip-pen nanolithography and micro-contact printing, facilitated by a process of surface etching and passivation of the GaAs. A quantitative analysis on the molecular diffusion on GaAs was conducted by examining the writing of nanoscale dot and line patterns by DPN, which agrees well with surface diffusion models. The functionality of the patterned thiol molecules was demonstrated by directed self-assembly of gold nanoparticles onto a template of 4-Aminothiophenol SAM on GaAs. The highly selective assembly of the Au NPs was evidenced with atomic force microscopy and scanning electron microscopy. The ability to precisely control the assembly of Au NPs on oxide-free semiconductor surfaces using molecular templates may lead to an efficient bottom-up method for the fabrication of nano-plasmonic structures.