(529d) Growth and Modification of Carbon Nanotubes By Atomic Layer Deposition of Ni and Cu for Spaceflight Instruments and Terrestrial Applications

Growth and Modification of Carbon
Nanotubes by Atomic Layer Deposition of Ni and Cu for Spaceflight Instruments
and Terrestrial Applications

background:white">Vivek
Dwivedi¹, Henry Degroh², Raymond A. Adomaitis³_,Hossein
Salami³, Alan Uy³, Aarathi
Vadapalli³, Brianna Sheard³

background:white">1
NASA Goddard Spaceflight Center, USA

background:white">2
NASA
Glenn Research Center, USA
3 University of Maryland, USA

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none">ALD is a cost-effective nanoadditive-manufacturing
technique that allows for the conformal coating of substrates with atomic
control in a benign temperature and pressure environment. Through the
introduction of paired precursor gases, thin films can be deposited on a myriad
of substrates regardless of topography. By providing atomic layer control,
where single layers of atoms can be deposited, the fabrication of metal
transparent films, precise nano-laminates, and coatings of nano-channels and
pores is achievable. A characteristic of
the surface adsorption and reaction mechanisms in ALD is that they are normally
self-limiting, allowing for atomically accurate control of nanometer (nm)
thickness. Therefore, high uniformity and precise thickness control make ALD
an attractive process for the creation of novel optical and other nano-scale
devices. The applicability of ALD as a mode for depositing the catalytic layer
for the growth of carbon nanotubes, CNTs, and using ALD to directly modify a
CNT substrate are discussed.

none">Stray light optics for space platform
instruments require components of the optical bench to be coated with a material
that suppresses light reflectance allowing for the imaging of extremely dimmed
objects. Coronagraphs are
key heliophysics instruments because they image coronal mass ejections (CMEs), which are the most energetic phenomena on the Sun. CMEs
have wide-ranging impact on the
heliosphere, from interplanetary
spacecraft to Earth-orbiting satellites, communications, and astronaut safety—in short, they are major drivers of space weather.
Coronagraphs reveal the structure and speed of CMEs when they are near the Sun
and provide essential input to predictive space weather models. In a typical
space-based coronagraph, an external occulter blocks light from the disk of the
Sun so that the corona (about a million times dimmer) can be imaged. The
occulter must suppress both diffracted light and stray light. Diffraction is
controlled by careful design of the occulter geometry, typically a curved
surface and the stray light reflectance is controlled by the occulter coating,
typically anodized black. A promising advance in stray light control is the
application of carbon nanotubes. Carbon nanotubes have shown to be 10 to 100
times blacker than anodized black from the Near UV to Far Infrared. In this
presentation we will show the utilization of ALD to deposit a catalytic layer
of Ni for the growth of CNTs for substrates with varying curvature with
enhanced reflectance properties.

none">There is great need for the increase
in electrical conductivity of wire, and also for the decrease in wire density.
Increases in electrical conductivity are needed to improve the function of
electronics, electric motors and everything else that runs on electricity, as
well as cables that transmit electricity. An increase in conductivity results
in greater efficiency due to lower power losses. The state-of-the art in wire
has not change much over the last 100 years. The conductor material of all
applicable wire and cable is made of either copper (Cu) or aluminum (Al).
Copper has superior conductivity and is used when space is limited, like in the
windings of an electric motor. It is believed that contributions to the
state-of-the-art can be made through improvements in conductivity and/or
density for Cu. This improvement can be accomplished by adding something to Cu
that is more conductive and/or less dense, and at the same time, not ruin the
conductivity of the Cu. The only material known to man that has significantly
higher conductivity and lower density than Cu is ballistically conducting,
metallic carbon nanotubes (CNT). color:black">ALD of conformal metallic copper films is an important research
area where such films are needed in the miniaturization and portability of
electronic devices. However, the miniaturization from the micro to nano regime
has led to Joule heating becoming a major concern in interconnect
applications. The conformal deposition on most high aspect ratio substrate
geometries is a challenge that ALD can solve.