29 research outputs found
Blending of nanoscale and microscale in uniform large-area sculptured thin-film architectures
The combination of large thickness ( m), large--area uniformity (75
mm diameter), high growth rate (up to 0.4 m/min) in assemblies of
complex--shaped nanowires on lithographically defined patterns has been
achieved for the first time. The nanoscale and the microscale have thus been
blended together in sculptured thin films with transverse architectures.
SiO () nanowires were grown by electron--beam evaporation onto
silicon substrates both with and without photoresist lines (1--D arrays) and
checkerboard (2--D arrays) patterns. Atomic self--shadowing due to
oblique--angle deposition enables the nanowires to grow continuously, to change
direction abruptly, and to maintain constant cross--sectional diameter. The
selective growth of nanowire assemblies on the top surfaces of both 1--D and
2--D arrays can be understood and predicted using simple geometrical shadowing
equations.Comment: 17 pages, 9 figure
Thin-Film Metamaterials called Sculptured Thin Films
Morphology and performance are conjointed attributes of metamaterials, of
which sculptured thin films (STFs) are examples. STFs are assemblies of
nanowires that can be fabricated from many different materials, typically via
physical vapor deposition onto rotating substrates. The curvilinear--nanowire
morphology of STFs is determined by the substrate motions during fabrication.
The optical properties, especially, can be tailored by varying the morphology
of STFs. In many cases prototype devices have been fabricated for various
optical, thermal, chemical, and biological applications.Comment: to be published in Proc. ICTP School on Metamaterials (Augsut 2009,
Sibiu, Romania
Erratum: The solar orbiter radio and plasma waves (RPW) instrument (Astronomy and Astrophysics (2020) 642 (A12) DOI: 10.1051/0004-6361/201936214)
The erratum concerns Fig. 9 entitled "Antenna radio-electrical properties" for which some of the parameters are not correct. The new figure with new parameters is provided in Fig. 1 of this corrigendum. Fig. 1. Corrected Antenna radio-electrical properties. (Figure Presented)
Sample preparation method for 3D size measurements of polystyrene nanoparticles with nominal 30, 50, 70 and 100 nm diameters by electron tomography
Periodic magnetic microstructures by glancing angle deposition
An advanced deposition technique known as glancing angle deposition (GLAD) [K. Robbie, J. C. Sit, and M. J. Brett, J. Vac. Sci. Technol. B 16, 1115 (1998); K. Robbie and M. J. Brett, U.S. Patent No. 5,866,204 (filed 1999)] has been used to fabricate periodic arrays of magnetic pillars and randomly seeded magnetic helices, posts, and chevrons. Because of the nature of initial film nucleation, the GLAD process normally distributes posts randomly on the substrate surface. We can grow periodic arrays of GLAD microstructures by suppressing the randomness inherent within the initial nucleation stage of film growth. Shadowing sites were fabricated by pre-patterning a thin titanium layer on silicon substrates into a square array using electron beam lithography. These sites shadow regions of the substrate from incident flux during film deposition and act as preferred nucleation sites for film growth. Using this process, we have fabricated periodic arrays of cobalt posts with a regular elemental period of 600 nm and post diameters and heights of 300 and 400 nm, respectively. Randomly seeded posts, helices, and chevrons were also fabricated. The mean separation for the randomly seeded posts was 350 nm with individual post diameters of 100\ufffd150 nm, while the separations for the helices and chevrons were less than 100 nm. X-ray diffraction, transmission electron microscopy, and a dc superconducting quantum interference device magnetometer were used to analyze the magnetic and crystal properties of both the periodic and randomly seeded arrays. A newly developed three-dimensional ballistic deposition simulator was used to simulate the growth of the periodic post arrays in order to better understand the growth mechanisms.NRC publication: N
Periodic magnetic microstructures by glancing angle deposition
An advanced deposition technique known as glancing angle deposition (GLAD) [K. Robbie, J. C. Sit, and M. J. Brett, J. Vac. Sci. Technol. B 16, 1115 (1998); K. Robbie and M. J. Brett, U.S. Patent No. 5,866,204 (filed 1999)] has been used to fabricate periodic arrays of magnetic pillars and randomly seeded magnetic helices, posts, and chevrons. Because of the nature of initial film nucleation, the GLAD process normally distributes posts randomly on the substrate surface. We can grow periodic arrays of GLAD microstructures by suppressing the randomness inherent within the initial nucleation stage of film growth. Shadowing sites were fabricated by pre-patterning a thin titanium layer on silicon substrates into a square array using electron beam lithography. These sites shadow regions of the substrate from incident flux during film deposition and act as preferred nucleation sites for film growth. Using this process, we have fabricated periodic arrays of cobalt posts with a regular elemental period of 600 nm and post diameters and heights of 300 and 400 nm, respectively. Randomly seeded posts, helices, and chevrons were also fabricated. The mean separation for the randomly seeded posts was 350 nm with individual post diameters of 100\ufffd150 nm, while the separations for the helices and chevrons were less than 100 nm. X-ray diffraction, transmission electron microscopy, and a dc superconducting quantum interference device magnetometer were used to analyze the magnetic and crystal properties of both the periodic and randomly seeded arrays. A newly developed three-dimensional ballistic deposition simulator was used to simulate the growth of the periodic post arrays in order to better understand the growth mechanisms.NRC publication: N