IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
rising partial pressure of
nitrogen gas was maintained.
The compositional depth profile
of this multilayer architecture
was analyzed by Secondary Ion
Mass Spectrometry (SIMS) using
Cs + primary ion beam. The Cs
Ti + and CsN 2+
quasimolecular
complexes were monitored
along with CsO + and CsSi + to
get the compositional variation
as a function of sputter depth.
Fig. 2 shows the composition
depth profiles for the elements
Ti, Si, N and O. The N/Ti ratio
increases with increase in
deposition pressure from 5.0 ×
10 -5 mbar, reaches a maximum
for films deposited at
5.0 × 10 -2 mbar and then
declines owing to the
preponderance of O 2 at higher
Fig.2 SIMS depth profile of TiN multilayers grown sequentialy on Si
substrate at various deposition pressures by RPLD
Fig.3 High Resolution TEM image of the RPLD grown TiN film
(Insert A) elasto-plastic deformation profile obtained by
nano-indentation (Insert B) selected area electron diffraction pattern
pressures. Thus it can be
concluded that the deposition
pressure of ~10 -2 mbar is the
optimal condition for growing
stoichiometric nanostructured
TiN coatings.
The high resolution TEM
image of the TiN film grown on
a NaCl substrate at 2 × 10 -2
mbar and the corresponding
Selected Area Electron
Diffraction (SAED) pattern is
shown in figure 3. These studies
indicated the formation of films
highly oriented in the
and directions. The d-
spacing calculated from the
diffraction pattern matches well
with the literature values
reported in PCPDF data. A
typical nanoindentation profile
of 800 nm thick TiN film coated
on silicon substrate at
2.0× 10 -2 mbar is shown as an
inset in the high resolution TEM
m i c r o s t r u c t u r e .
Nanoindentation studies of thin
films, are aimed at providing
better interpretations of the
elastic modulus, yield strength,
strain hardening and hardness
of the surface only. The
hardness and modulus of the
film at a depth of 80 nm
calculated from the loading
and unloading profile using
Oliver-Pharr technique is 20
GPa and 231 GPa, respectively.
Efforts are on to synthesize AlN,
ZrN and NbN coatings in
similar way with an aim to
produce multilayered
nanostructured films with
heterolaminate architecture.
150 BASIC RESEARCH