Photo-Chemically Directed Self-Assembly of Carbon Nanotubes on Surfaces

TL;DR

This paper presents a novel, simple UV light-based method for patterning surfaces with chemical monolayers to precisely position carbon nanotubes for electronic applications.

Contribution

It introduces a one-step, photo-chemically controlled patterning technique enabling wafer-scale placement of CNTs without complex fabrication steps.

Findings

Effective UV patterning of monolayers achieved

Precise CNT placement demonstrated

Compatible with standard lithography processes

Abstract

Transistors incorporating single-wall carbon nanotubes (CNTs) as the channel material are used in a variety of electronics applications. However, a competitive CNT-based technology requires the precise placement of CNTs at predefined locations of a substrate. One promising placement approach is to use chemical recognition to bind CNTs from solution at the desired locations on a surface. Producing the chemical pattern on the substrate is challenging. Here we describe a one-step patterning approach based on a highly photosensitive surface monolayer. The monolayer contains chromophopric group as light sensitive body with heteroatoms as high quantum yield photolysis center. As deposited, the layer will bind CNTs from solution. However, when exposed to ultraviolet (UV) light with a low dose (60 mJ/cm2) similar to that used for conventional photoresists, the monolayer cleaves and no longer binds CNTs. These features allow standard, wafer-scale UV lithography processes to be used to form a patterned chemical monolayer without the need for complex substrate patterning or monolayer stamping.