Materials Characterization
MNEC does multiple film
characterization which produce new results, both fundamental and
practical.
Tapping mode atomic force microscope work with
X-ray diffraction work have identified a mechanism by which the very
small amounts of nitrogen can act catalytically to both dissolve
defective crystallites and enhance the grow of larger more perfect
crystallites.
The electrical properties of the nitrogen grown
series have been analyzed DC through 1 MHz, and an unexpected peak in
the dc resistivity has been found. A corresponding increase in the
resistivity of the grain boundaries has been observed directly for the
first time using scanning tunneling spectroscopy.
One of the major question about films processed
into components for MEMS devices is the amount of stress introduced by
the processing. We are quantitatively investigating stress questions for
laser processed diamond films for MEMS applications by a combination of
x-ray residual stress analysis for large area analysis and polarized
Raman for close-up.
Electronic Structure of Diamond and Related
Materials
We are performing integrated materials and
electronic properties investigations of charge transport in
polycrystalline diamond films, analyzing the effects of the
morphological differences, nitrogen effects, and thermal annealing
effects on the total conduction within the films. The investigations are
proceeding using a Macroscopic/Microscopic approach. Macroscopic
analysis of the films? conductance, resistance, susceptance and
reactance is performed using Impedance Spectroscopy (IS). The results
are analyzed in light of a theoretical model which incorporates bulk,
hopping and and grain boundary electrical conduction mechanisms, .
modeled using a four path physical model which include dc resistance,
geometric capacitance, hopping and grain boundaries. We couple our
Macroscopic analysis to a Microscopic analysis of local morphologies and
electronic properties, using Scanning Tunneling Microscopy and
Spectroscopy. We are particularly investigating the local electronic
structure of the various morphologies at the surfaces, and the
variations in these introduced by nitrogen, or by nitrogen plus thermal
annealing. These are atomic level investigations. Scanning Tunneling
Microscopy (STM) is the preferred tool for truly atomic scale resolution
of surface morphology. Scanning Tunneling Spectroscopy (STS) is used to
compare the local electronic structures generated by the local atomic
lattice structures through analysis of atomic scale tunneling
current-bias voltage curves.
Investigations in progress:
- Macroscopic/Microscopic Investigation of
Charge Injection and Thermal Stability
- Macroscopic/Microscopic investigation of
electronic properties of N2-CH4-H2
diamond thin films
