1 Introduction to Laser Micro-to-Nano Manufacturing
57
Fig. 1.40 AFM height
image of a graphene device
after laser pre-patterning and
electroburning Modified
from [242]
the DNA molecular template, which leads to creating a conductive metallic wire by
bridging gaps between nucleation sites. Various metals have been employed including
silver [249], palladium [250], platinum [251] and gold [252]. The disadvantage of
this metallization method is the non-uniformity over the entire DNA scaffold. To
address the uniformity problem, sequence-specific molecular lithography was further
developed [253]. In molecular lithography, masks used in conventional photolithography is replaced by the information encoded in the DNA molecules. In 2003 Keran
et al. reported a caritative process for assembly a CNT along with a pre-designed
template on a DNA substrate [254]. In this research, a framework of using DNA and
homologous genetic recombination for CNT self-assembly is established. By using
homologous recombination, which is a protein-mediated reaction between two DNA
molecules, a CNT was localized at a desired DNA scaffold molecule. RecA protein
from Escherichia coli bacteria was used in the process. After CNT was localized,
DNA molecule is metallized by AgNO 3 . Conductive metallic wires were formed by
silver reduction along the DNA. In here, RecA act as a protector to protects the active
area of the transistor against metallization. Subsequently, electroless gold plating was
applied using the silver clusters as nucleation centers to create a highly conductive
gold electrode. Figure 1.41 shows an SEM image of an individual SWNT contacted
by two DNA-templated gold nanowires.
Although current approaches of making DNA-templated wires have shown a
promising development, it is still facing a difficulty in the production of smallerscale nanostructures and devices, which is the major drawback [255]. To overcome
this problem, better methods to realize conductance based on DNA scaffolds have to
be developed. The laser-induced photochemistry is probably a promising solution.
57
Fig. 1.40 AFM height
image of a graphene device
after laser pre-patterning and
electroburning Modified
from [242]
the DNA molecular template, which leads to creating a conductive metallic wire by
bridging gaps between nucleation sites. Various metals have been employed including
silver [249], palladium [250], platinum [251] and gold [252]. The disadvantage of
this metallization method is the non-uniformity over the entire DNA scaffold. To
address the uniformity problem, sequence-specific molecular lithography was further
developed [253]. In molecular lithography, masks used in conventional photolithography is replaced by the information encoded in the DNA molecules. In 2003 Keran
et al. reported a caritative process for assembly a CNT along with a pre-designed
template on a DNA substrate [254]. In this research, a framework of using DNA and
homologous genetic recombination for CNT self-assembly is established. By using
homologous recombination, which is a protein-mediated reaction between two DNA
molecules, a CNT was localized at a desired DNA scaffold molecule. RecA protein
from Escherichia coli bacteria was used in the process. After CNT was localized,
DNA molecule is metallized by AgNO 3 . Conductive metallic wires were formed by
silver reduction along the DNA. In here, RecA act as a protector to protects the active
area of the transistor against metallization. Subsequently, electroless gold plating was
applied using the silver clusters as nucleation centers to create a highly conductive
gold electrode. Figure 1.41 shows an SEM image of an individual SWNT contacted
by two DNA-templated gold nanowires.
Although current approaches of making DNA-templated wires have shown a
promising development, it is still facing a difficulty in the production of smallerscale nanostructures and devices, which is the major drawback [255]. To overcome
this problem, better methods to realize conductance based on DNA scaffolds have to
be developed. The laser-induced photochemistry is probably a promising solution.