|dc.description.abstract||Diamond materials have been the subject of intensive research for decades. Since the
fabrication of diamond structures by chemical vapor deposition was demonstrated in
the 1960’s, research and developments effor boomed. In 1994, ultrananocrystalline
diamond(UNCD)films were developed in a microwave plasma assisted chemical vapor
was demonstrated thatUNCD’s electrical conductivity properties could be tuned into
semiRmetallic and evensuperconducting via the addition of dopants during synthesis.
Particularly, the addition of nitrogen during MPCVD growth allowed growth of n"type
electrically conductive UNCD films. In this work, we report the synthesis and
characterization of NUNCD thin films for various applications.
The first application is the development of a NUNCD hydrogen-terminated(NUNCD(H))
photocathode for photoinjector applications. Hydrogen-terminated materials display
negative!electron affinity (NEA).In NEA materials, electrons from the conduction band
can be emitted directly into the vacuum. Photocathodes displaying NEA are bright
electron sources because they have high quantum efficiency (QE). The NUNCD(H)
photocathode displayed a QE of ~10R3 at 254nm, which of interest to the photoinjector’s
R&D community.The NUNCD(H) PC was also sensitive in the visible range at 405nm and
440nm. The experimental details and future directions are presented in this work.
Secondly, a planar NUNCD field emission cathode (FEC) was developed and was tested
in an RF electron injector. The emission from the NUNCD grain boundaries allowed the
simple geometry of the FEC, avoiding lithography and transfer steps.The NUNCD FEC demonstrated peak!currents of 1 –80 mA at gradients of 45 –65MV/m.Thecurrent
stability was tested over the course of an hour with excellent results.Raman
spectroscopy and electron microscopy characterization done after testing demonstrated
the FEC’s robustness.
Finally, an NUNCD based nanoelectromechanical (NEM) switch was developed via an
electron beam lithography / reaction ion etching (EBLRRIE) fabrication pathway. The
fabrication pathway is demonstrated and the optimization of each fabrication step is
presented. The!fabricated NUNCD NEM switch exhibited intrinsic compressive stress in
the NUNCD nanowire source element. Previous research efforts suggest stress
engineering can be achieved by reducing the pressure during the MPCVD growth or by
increasing the thickness of the NUNCD layer. The results are discussed at length.
The results presented in this work showcase the properties of NUNCD films and
properties that have the potential for commercial applications.||