Substrate Impact on MR Characteristics of Carbon Nano Films Explored via AFM and Raman Analysis

Recent advances in the fabrication and classification of amorphous carbon (a-Carbon) thin films play an active part in the field of surface materials science. In this paper, a pulsed laser deposition (PLD) technique through controlling experimental parameters, including deposition time/temperature and laser energy/frequency, has been employed to examine the substrate effect of amorphous carbon thin film fabrication over SiO2 and glass substrates. In this paper, we have examined the structural and magnetoresistance (MR) properties of these thin films. The intensity ratio of the G-band and D-band (ID/IG) were 1.1 and 2.4, where the C(sp2) atomic ratio for the thin films samples that were prepared on glass and SiO2 substrates, were observed as 65% and 85%, respectively. The MR properties were examined under a magnetic field ranging from −9 T to 9 T within a 2-K to 40-K temperature range. A positive MR value of 15% was examined at a low temperature of 2 K for the thin films grown on SiO2 substrate at a growth temperature of 400 °C using a 300 mJ/pulse laser frequency. The structural changes may tune the magnetoresistance properties of these a-Carbon materials. These results were demonstrated to be highly promising for carbon-based spintronics and magnetic sensors.

Download Full-text

Structural and Magnetoresistance Properties of Transfer-Free Amorphous Carbon Thin Films

Crystals ◽

10.3390/cryst9030124 ◽

2019 ◽

Vol 9 (3) ◽

pp. 124

Author(s):

Awais Saleemi ◽

Ali Abdullah ◽

Muhammad Saeed ◽

M. Anis-ur-Rehman ◽

Ayyaz Mahmood ◽

...

Keyword(s):

Thin Films ◽

Amorphous Carbon ◽

Materials Science ◽

Physical Property Measurement System ◽

Chemical Vapor ◽

Physical Property ◽

Interesting Phenomenon ◽

Sio2 Substrate ◽

Carbon Thin Films ◽

Cost Efficient

The control of the morphologies and thus the optical, electrical, and magnetic effect of 2D thin films is a challenging task for the development of cost-efficient devices. In particular, the angular dependent magnetoresistance (MR) of surface thin films up to room temperature is an interesting phenomenon in materials science. Here, we report amorphous carbon thin films fabricated through chemical vapor deposition at a SiO2 substrate. Their structural and angular magnetoresistance properties were investigated by several analytical tools. Specifically, we used a physical property measurement system to estimate the magnitude of the angular MR of these as-prepared sample thin films from 2 K to 300 K. An angular MR magnitude of 1.6% for the undoped a-carbon thin films was found up to 300 K. Under the magnetic field of 7 T, these films possessed an angular MR of 15% at a low temperature of 2 K. A high disorder degree leads to a large magnitude of MR. The grain boundary scattering model was used to interpret the mechanism of this angular MR.

Download Full-text

Grain Orientation and Strain Measurements in Sub-Micron wide Passivated Individual Aluminum Test Structures

MRS Proceedings ◽

10.1557/proc-612-d8.8.1 ◽

2000 ◽

Vol 612 ◽

Cited By ~ 8

Author(s):

N. Tamura ◽

B. C. Valek ◽

R. Spolenak ◽

A. A. MacDowell ◽

R. S. Celestre ◽

...

Keyword(s):

Thin Films ◽

Grain Orientation ◽

Strain State ◽

Structural Changes ◽

Materials Science ◽

Local Level ◽

Subsequent Treatment ◽

Shear Stresses ◽

X Ray ◽

Individual Grains

AbstractAn X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains.

Download Full-text

Aluminum Nitride Thin Films Grown by Plasma-Assisted Pulsed Laser Deposition on Si Substrates

MRS Proceedings ◽

10.1557/proc-468-87 ◽

1997 ◽

Vol 468 ◽

Cited By ~ 1

Author(s):

M. Okamoto ◽

T. Ogawa ◽

Y. Mori ◽

T. Sasaki

Keyword(s):

Thin Films ◽

Pulsed Laser Deposition ◽

Laser Energy ◽

Pulsed Laser ◽

Atomic Ratio ◽

Laser Deposition ◽

X Ray ◽

Si Substrates ◽

High Laser ◽

High Laser Energy

ABSTRACTThe smooth and highly oriented AlN films were obtained using pulsed laser deposition from sintered AlN target in a nitrogen ambient. The XRD investigation revealed that highly oriented AlN thin films along the c-axis (AlN (0002)) normal to the substrate were obtained both on Si(111) and on Si(100) substrates. The (0002) x-ray peak width became narrower with increasing substrate temperature. The CL investigation showed that AlN films at high laser energy density (Ed) indicated CL peak at shorter wavelength (306nm) than that at low Ed (394nm). N/Al atomic ratio in AlN films grown at high Ed also increased as comparison with the films grown at low Ed.

Download Full-text

Electron-diffraction studies of amorphous carbon thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151337 ◽

1993 ◽

Vol 51 ◽

pp. 1100-1101

Author(s):

David A. Muller

Keyword(s):

Thin Films ◽

Electron Diffraction ◽

Amorphous Carbon ◽

Glassy Carbon ◽

Spherical Structure ◽

Local Ordering ◽

Carbon Arc ◽

Similar Appearance ◽

Carbon Thin Films ◽

Large Spherical

The sp2 rich amorphous carbons have a wide variety of microstructures ranging from flat sheetlike structures such as glassy carbon to highly curved materials having similar local ordering to the fullerenes. These differences are most apparent in the region of the graphite (0002) reflection of the energy filtered diffracted intensity obtained from these materials (Fig. 1). All these materials consist mainly of threefold coordinated atoms. This accounts for their similar appearance above 0.8 Å-1. The fullerene curves (b,c) show a string of peaks at distance scales corresponding to the packing of the large spherical and oblate molecules. The beam damaged C60 (c) shows an evolution to the sp2 amorphous carbons as the spherical structure is destroyed although the (220) reflection in fee fcc at 0.2 Å-1 does not disappear completely. This 0.2 Å-1 peak is present in the 1960 data of Kakinoki et. al. who grew films in a carbon arc under conditions similar to those needed to form fullerene rich soots.

Download Full-text

NITROGEN INCORPORATED HYDROGENATED AMORPHOUS CARBON THIN FILMS DEPOSITED BY MICROWAVE SURFACE-WAVE PLASMA CHEMICAL VAPOR DEPOSITION

International Journal of Modern Physics B ◽

10.1142/s0217979209048559 ◽

2009 ◽

Vol 23 (09) ◽

pp. 2159-2165 ◽

Cited By ~ 2

Author(s):

SUDIP ADHIKARI ◽

MASAYOSHI UMENO

Keyword(s):

Thin Films ◽

Chemical Vapor Deposition ◽

Surface Wave ◽

Amorphous Carbon ◽

Vapor Deposition ◽

Chemical Vapor ◽

Plasma Chemical ◽

Hydrogenated Amorphous Carbon ◽

Plasma Chemical Vapor Deposition ◽

Hydrogenated Amorphous

Nitrogen incorporated hydrogenated amorphous carbon (a-C:N:H) thin films have been deposited by microwave surface-wave plasma chemical vapor deposition on silicon and quartz substrates, using helium, methane and nitrogen ( N 2) as plasma source. The deposited a-C:N:H films were characterized by their optical, structural and electrical properties through UV/VIS/NIR spectroscopy, Raman spectroscopy, atomic force microscope and current-voltage characteristics. The optical band gap decreased gently from 3.0 eV to 2.5 eV with increasing N 2 concentration in the films. The a-C:N:H film shows significantly higher electrical conductivity compared to that of N 2-free a-C:H film.

Download Full-text

Strain-stabilized superconductivity

Nature Communications ◽

10.1038/s41467-020-20252-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

J. P. Ruf ◽

H. Paik ◽

N. J. Schreiber ◽

H. P. Nair ◽

L. Miao ◽

...

Keyword(s):

Thin Films ◽

Materials Science ◽

Condensed Matter ◽

Quantum States ◽

Low Energy ◽

Superconducting Transition ◽

Superconducting Properties ◽

Detailed Understanding ◽

Epitaxial Strain ◽

Promising Strategy

AbstractSuperconductivity is among the most fascinating and well-studied quantum states of matter. Despite over 100 years of research, a detailed understanding of how features of the normal-state electronic structure determine superconducting properties has remained elusive. For instance, the ability to deterministically enhance the superconducting transition temperature by design, rather than by serendipity, has been a long sought-after goal in condensed matter physics and materials science, but achieving this objective may require new tools, techniques and approaches. Here, we report the transmutation of a normal metal into a superconductor through the application of epitaxial strain. We demonstrate that synthesizing RuO2 thin films on (110)-oriented TiO2 substrates enhances the density of states near the Fermi level, which stabilizes superconductivity under strain, and suggests that a promising strategy to create new transition-metal superconductors is to apply judiciously chosen anisotropic strains that redistribute carriers within the low-energy manifold of d orbitals.

Download Full-text