Titanium nitride (TiN)/nickel (Ni) composite coatings were synthesized by plasma assisted metal-organic chemical vapour deposition (PAMOCVD) using organo-metallic and metal-organic complexes namely dichlorobis(5- cyclopentadienyl)titanium (IV) for titanium and N,N'-ethylene-bis(2,4-pentanedion-iminoato)nickel(II) for nickel. The growth of such films was investigated in nitrogen (N2) plasma environment in the substrate temperature range of 450- 550ºC at a deposition pressure of 0.5-1 mbar. Prior to the deposition of films, the Ti precursor was subjected to the equilibrium vapour pressure measurements by employing TG/DTA in transpiration mode, which led to the value of 109.2 ± 5.6 kJ mol-1 for the standard enthalpy of sublimation (Ho sub). The phase identification using glancing incidence x-ray diffraction showed Ni/TiN is a nanocomposite coating containing nanocrystals of Ni and TiN with face centered cubic structure. Scanning electron microscopy revealed a uniform surface morphology of the films, while chemical analysis by energy dispersive analysis confirmed the presence of titanium, nickel and nitrogen in the composite films.

1. Micro and Nanosystems, 2012, 4, 199-207
199
Deposition of Ni/TiN Composite Coatings by a Plasma Assisted MOCVD
Using an Organometallic Precursor
S. Arockiasamya*, T. Maiyalaganb, P. Kuppusamic, C. Mallikad and K.S. Nagarajae
a
VIT University Chennai Campus, Chennai-600 048, Tamil Nadu, India
b
School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive Singapore 639798
c
Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam-603 102, Tamil Nadu,
India
d
e
RRDD, IGCAR, Kalpakkam-603 102, Tamil Nadu, India
Loyola College, Department of Chemistry and LIFE, Chennai-34
Abstract: Titanium nitride (TiN)/nickel (Ni) composite coatings were synthesized by plasma assisted metal-organic
chemical vapour deposition (PAMOCVD) using organo-metallic and metal-organic complexes namely dichlorobis( 5cyclopentadienyl)titanium (IV) for titanium and N,N'-ethylene-bis(2,4-pentanedion-iminoato)nickel(II) for nickel. The
growth of such films was investigated in nitrogen (N2) plasma environment in the substrate temperature range of 450550ºC at a deposition pressure of 0.5-1 mbar. Prior to the deposition of films, the Ti precursor was subjected to the
equilibrium vapour pressure measurements by employing TG/DTA in transpiration mode, which led to the value of 109.2
± 5.6 kJ mol-1 for the standard enthalpy of sublimation ( Hosub). The phase identification using glancing incidence x-ray
diffraction showed Ni/TiN is a nanocomposite coating containing nanocrystals of Ni and TiN with face centered cubic
structure. Scanning electron microscopy revealed a uniform surface morphology of the films, while chemical analysis by
energy dispersive analysis confirmed the presence of titanium, nickel and nitrogen in the composite films.
Keywords: Chemical vapour deposition, nano-composite, nickel, titanium nitride, metallic Ti, thin films, vapour pressure.
1. INTRODUCTION
Research in hard coatings for components used in heavy
engineering, automotive and aerospace has evolved from the
single phase coatings (TiN, CrN etc.,) to multilayered to
nano-composite coatings. Titanium nitride (TiN) is a
refractory, gold-coloured material that has found use in
decorative and mechanical wear-resistant coatings and in
microelectronic circuits [1, 2]. The cubic TiN phase exhibits
metallic behaviour, extreme hardness, high melting point
(3000oC), remarkable chemical resistance (e.g. inert to
organic solvents and inorganic acids), and low temperature
superconductivity [3, 4]. But due to porosity, internal stress
and poor adhesion, TiN coating alone cannot be used for
corrosion protection and the corrosion resistance of hybrid
coatings such as Ni-P/TiN have been found to be better than
the individual counterparts [5].
Such type of nano-composite coatings or hybrid coatings
have been prepared by several techniques such as, electroless
plating prepared by dc magnetron sputtering [5,], ultrasonic
electrodeposition [6, 7], ion beam sputtering [8], dc
magnetron sputtering [9] and high speed jet electroplating
[10]. Similar to Ni/TiN, nano-composite coating of ZrN/Cu
is also found to exhibit superior hardness [11]. In most cases,
*Address correspondence to this author at the VIT University Chennai
Campus, Chennai-600 048, Tamil Nadu, India; Tel: +91-44-3993 1233;
Fax: +91-44-3993 2555; E-mails: sa_samy@yahoo.com,
arockiasamy.s@vit.ac.in
1876-4037/12 $58.00+.00
the nickel is electroless plated first on the surface of the
substrate to be protected from corrosion and then TiN
coating is sputter deposited. Chemical vapour deposition
(CVD) is known for conformal coverage, flexibility towards
the shape of the substrate, including the capability to create
films on the inner surface of pipes and on flexible substrates,
and high quality of the products with good adhesions. These
advantages make the CVD techniques more relevant for any
practical applications [12]. High quality thin films could be
obtained by employing metallo-organic CVD (MOCVD) and
atomic layer deposition (ALD) among other techniques [13].
MOCVD is a special case of CVD in which one or more of
the gas-phase precursors are metallo-organic compounds,
whose flow and mixing can be controlled to get composite
coatings [14].
We have reported the synthesis and microstructural
properties of Ni/TiO2 recently [12]. In the present
investigation we have reported the deposition of Ni/TiN
nano-composite thin-film by employing plasma assisted
CVD using the combination of metallo-oranic and organometallic complexes as source materials for Ni and TiN
respectively along with the vapour pressure study of Ti
precursor. Though there are a few reports on the
development and application of Ni/TiN composite thin films
prepared by host of physical techniques [5-10], no report
could be traced for the simultaneous vapour phase deposition
of Ni/TiN by a Plasma Assisted Metallo Organic CVD
(PAMOCVD) or plasma assisted organo-metallic CVD
(PAOMCVD) using a metallo-organic nickel complex and
© 2012 Bentham Science Publishers

2. 200 Micro and Nanosystems, 2012, Vol. 4, No. 3
Arockiasamy et al.
an organo-metallic titanium complex as precursors.
However, for a successful deposition of thin films for
industrial applications using CVD, it is necessary to have a
precursor which is commercially available at a reasonable
price, has sufficient thermal stability and vapour pressure and
good shelf life. Therefore, the decomposition and thermal
stability of the precursor of Ti complex is also investigated.
2. EXPERIMENTAL PROCEDURES
2.1. Non-Isothermal TG/DTA of Ti Complex
Thermo-gravimetry (TG) was used to study the
decomposition pattern of Ti complex because it can throw
light on thermal stability, melting, decomposition and more
importantly volatility which is a primary condition for
chemical vapour deposition. TG was recorded in an inert
atmosphere like argon or nitrogen with a heating rate of
10°C min-1 to avoid oxidation of the complexes. The calcined
-alumina powder of even weight was used as the reference.
The dynamic TG runs on all the compounds were
recorded at a linear heating rate of 10oC/min using a thermoanalyser (Perkin-Elmer, Pyris-Diamond). High purity
nitrogen/argon (purity >99.99%) dried by passing through
refrigerated molecular sieves (Linde 4A) was used as the
purge gas. The complex was dried under vacuum with
anhydrous calcium chloride as a desiccant prior to the TG
runs. Sample weighing 1.579 mg was loaded in an -alumina
crucible (5m 5 mm x mm) and placed in the sample pan and
was subsequently dried in situ at 50oC for a few minutes to
remove adsorbed moisture, if any. The purpose of the runs
was to observe the mass loss steps besides identifying the
final temperature for attaining nil residue or constant weight
or decomposition pattern.
2.2. Vapour Pressure Measurement of Ti Complex
Prior to the deposition of the thin films using OMCVD,
vapour
pressure
measurement
of
dichlorobis( 5cyclopentadienyl)titanium (IV) or titanocene dichloride
(Ti(Cp)2Cl2) complex was carried out using the TG-based
transpiration technique. The block diagram of the thermoanalyser, modification for its functioning in the transpiration
mode, including precise flow calibration of the carrier gas,
using a capillary glass flow meter and corrections for
apparent weight losses in isothermal modes have been
described elsewhere [15]. The configuration of the thermoanalyser with horizontal dual-arm single-furnace has
eliminated/minimized the apparent weight changes caused
by temperature gradients, convection currents within the
furnace tube (made of alumina), buoyancy, thermomolecular drag and electrostatic effects. The arms of the
thermo-balance served as the temperature-cum-DTA sensors.
The calibration of the R-type thermocouple (Pt-13%Rh/Pt)
was carried out using the recommended melting point
standards (such as indium and tin) in order to make the Tscale of the balance conform to the International Practical
Temperature Scale 1968 (IPTS-68) amended in 1975.
o
o
Heating the furnace to 900 C at a rate of 15 C/min under
nitrogen gas at the purge rate of 12 dm3h-1 and then cooling
under the same conditions to near-ambient temperature
(about 40oC) was done for heat cleaning the furnace before
every vapour pressure measurement. Thereafter, the samples,
finely powdered using an agate mortar and pestle, weighing
in the range of 40-46 mg were spread out on a shallow
alumina crucible mounted for vapour pressure measurements
and was carefully flushed with nitrogen at a rate of 6 dm3h-1
at ambient temperature.
The initial heating to just below 10oC of the actual vapour
pressure measurement temperature for all the complexes was
rather rapid (10oC/min). After the stabilization of the
temperature, the complexes were heated at 2oC/min in steps of
10oC to the respective isothermal temperatures. The flow rate
of 6 dm3h-1 for nitrogen gas was employed to ensure
isothermal equilibrium vapourisation in all the isothermal
steps. The flow rates were monitored by a mass flow
controller (model-MKS, Type 1179A, USA). The accuracy of
the temperature measurements was adjusted to be better than
±0.05 K, using the recommended melting point standards
namely indium, tin and aluminium. The reproducibility of the
T-scale was assessed to be better than ±0.2 K.
2.3. Designing of Plasma Assisted CVD System
PAOMCVD was performed in a custom built dual wall
semi-cylindrical chamber made up of type 304 stainless steel
with an internal diameter of 430 mm and a height of 310 mm
(Fig. 1). The chamber of the PAOMCVD was evacuated
using a rotary pump (model VT-4012; Vacuum Techniques,
India) connected to one port and the electrical connection to
substrate heater and thermocouple were connected to the
other two ports. The port at the back was for the line which
carried the complex vapour and the other port at left was to
pass the by-pass gas. The two ports at the right hand side
were used to monitor the vacuum and air leaking
respectively. A pair of parallel plate circular electrodes of
diameter of 270 mm, made of stainless steel was used to
establish the symmetric reactor. The bottom grounded
electrode worked as a substrate holder as well. The diameter
of the substrate platform was large enough, so that 13 wafers
of 2 inch (50 mm) can be processed at a time. The heater
(halogen lamp of 800W) provided at the bottom of the lower
electrode served the purpose of heating the substrate.
Pulsed plasma source (ENI, RPG 50, 5000 W, USA)
connected to the upper electrode was used to sustain the
plasma in the reactor at 100 kHz with pulse time of 2976 ns.
The power of the plasma were varied by changing the
voltage and current. Four mass flow controllers (MFCS)
(MKS, type 1179A, USA) were used to control and monitor
(using four channel readout, MKS, type 247, USA) the flow
of various reactant gases like nitrogen, argon and hydrogen.
By-pass gas flow was attached with two 100g capacity
precursor tanks and a mixing chamber, which facilitated the
heating of precursors separately and mixing them in the
vapour phase prior to their entry into the CVD chamber.
Temperature controllers (Eurotherm) were used to
control/monitor the temperature of the substrate, precursor
chambers and vapour line by using K-type thermocouple.
2.4. Deposition and Characterization Methods
It is deemed as essential to optimize the process
parameters since they play a vital role in determining the
composition and properties of the thin film grown by CVD
[16]. Therefore, various process parameters such as chamber
pressure, substrate temperature, precursor chamber

3. Deposition of Ni/TiN Composite Coatings by a Plasma Assisted
Micro and Nanosystems, 2012, Vol. 4, No. 3
Substrates
Anode
By-Pass line
201
MFC4
View port
MFC3
Vapour line
HT Valve
Cathode
CVD Chamber
Mixing
Chamber
H2
Gas in
MFC1
Butterfly Valve
Valves
Ar
N2
PC1
MFC2
PC2
Precursor
Pellets
Cold
Trap
Rotary
Pump
Exhaust
Temperature-controlled
region
PC = Precursor Chamber
MFC = Mass Flow Controller
Fig. (1). Schematic diagram of the PA-MO(Organo Metallic)CVD system used in the present study.
temperature (based on the temperature of melting and
congruent sublimation of precursor), carrier gas flow rates,
pulsed plasma power, inter-electrode distance were
optimised by carrying out repeated trial and error
experiments for the deposition of Ni/TiN composite films.
The optimised deposition conditions for the coating of
Ni/TiN thin-films are summarized in Table 1.
The solid precursor of nickel, namely N,N’-ethylenebis(2,4-pentanedione-iminoato)nickel(II), Ni(acac)2en was
synthesized at the laboratory scale and was used for the
deposition of Ni/TiN thin film. The commercial grade
organo-metallic,
dichlorobis( 5-cyclopentadienyl)titanium
Table 1. Typical Growth Parameters for the Deposition of
Ni/TiN Nanocomposite Coatings using [Ti(Cp)2Cl2]
for Ti and Ni(acac)2en for Ni as Vapour Sources
Precursors for Ti
Cp2TiCl2
Precursors for Ni
Ni(acac)2en
Substrate temperature
550oC
Colour of the coating
Golden Yellow
Substrates
SS 316 and Silicon (100) oriented wafer
Pulsed DC voltage
201 V
Plasma current
150 mA
Electrode distance
45 mm
Base vacuum
220 x 10-3 mbar
Deposition pressure
0.5-1 mbar
Precursor chamber
temperature
150-250oC
Temperature of line heater
195-205oC
Gas flow rate
Carrier gas: nitrogen, 50sccm
By-pass gas: nitrogen, 200sccm
Deposition time
60 min
Growth rate
0.5<m
(IV), Ti(Cp)2Cl2 was used as titanium precursor. The choice
of Ti(Cp)2Cl2 as vapour source of titanium stems from the
fact that it does not contain any oxygen atom in its ligand
moiety and could be considered as a precursor of the
deposition of non-oxygen-based thin films of titanium. A
solid metallo-organic precursor was chosen for its thermal
stability, sufficient volatility, less toxicity and easy handling.
The silicon wafers with <100> orientation and
metallographically polished (with 0.2
m roughness)
stainless steel (SS) substrates were used after ultrasonic
cleaning by acetone and methanol. Substrates of dimension
of 10 mm 10 mmx0.5 mm were loaded in the chamber and
the chamber was evacuated to a base pressure of 30 10-3
mbar. After the initial evacuation of the CVD chamber, a
base pressure value of 1.2 10-1 mbar was obtained by
discharging nitrogen gas through the bypass line to strike the
plasma in the deposition zone. The temperature of the
substrate (Ts) was then increased slowly to the desired value
of 550oC at a heating rate of 12.5oCmin-1 and it was
maintained constant during the course of the complete
deposition process. When the temperature reached a value of
100oC, plasma was created in the chamber by applying high
voltage between the two electrodes. This helped in surface
etching of the substrates. After reaching the desired substrate
temperature of 550oC, the temperature of the line heater was
increased slowly and maintained in the range of 200-210oC
for most of the depositions. This followed the heating of the
precursor chambers. After reaching the vapour flow zone,
the rate of increase in the temperature was kept rather low in
order to ensure complete vapourisation and transportation of
precursors vapour continuously to the CVD chamber. This
helped in achieving uniform thin-film coating over the
substrates. After all the vapour was consumed, the supply of
carrier gas was stopped and the high temperature valve
(Swage Lock, SS-4BW) was closed to arrest vapour flow.
The flow through the by-pass was continued until the
samples were cooled down to room temperature in a reactive
plasma environment.
The thickness of the films was measured by SloanDektok-3010 surface profilometry. The deposited films were

4. 202 Micro and Nanosystems, 2012, Vol. 4, No. 3
Arockiasamy et al.
Fig. (2). Non-Isothermal TG/DTA of Ti(Cp)2Cl2 compound.
characterized by glancing incidence x-ray diffraction
(GIXRD) by employing STOE high-resolution X-ray
diffractometer with CuK ( = 1.5406 ) radiation and the
scan was performed in 2 mode over a 2 range of 20-80o.
For all the measurements, the angle of incidence of X-rays
was kept at 0.3o. The surface morphology of the films was
examined using a Philips XL-30 scanning electron
microscope equipped with an energy dispersive X-ray (EDX)
spectrometer.
3. RESULTS AND DISCUSSION
3.1. Thermal Analysis and Vapour Pressure Measurements of the Precursor
The compound bis( 5-cyclopentadienyl) titanium (II)
chloride, Ti(Cp2)Cl2 was found to satisfy almost all the
conditions for a ideal precursors [17, 18] and hence chosen
as the precursor for the deposition of Ni/TiN thin film using
CVD. The thermal analysis and vapour pressure
measurements of nickel complex namely, N,N’-ethylenebis(2,4-pentanedione-iminoato)nickel(II), Ni(acac)2en used
in the present investigation for the co-deposition of Ni/TiN
has been reported earlier from our group [19, 20].
The crucial test for any precursor is its thermal
characterization and hence Ti(Cp)2Cl2 was subjected to
thermal analysis. The recorded TG/DTA graph using a
horizontal dual arm single furnace thermo-analyser at a
heating rate of 10oC/min using high purity (99.99%) N2 as a
purge gas is produced in Fig. (2). The thermal behaviour of
Ti(Cp)2Cl2 as observed from Fig. (2) shows that the
compound is thermally stable up to a temperature of 191oC
and looses only 3% (0.5H2O), which could be ascribed to the
evaporation of adsorbed moisture and not due to the loss of
any component from the compound. It undergoes
vapourisation after melting at 267oC as evidenced by a small
endotherm in DTA. The melting temperature, volatility and
Table 2. Equilibrium Vapour Pressure of Titanium Compound
Against the Temperature
s. no
T (K)
W (mg)
Pe (Pa)
1
402.18
0.0048
0.011
2
412.44
0.0130
0.029
3
422.82
0.0249
0.058
4
433.21
0.0472
0.113
5
443.54
0.0983
0.242
6
454.01
0.2067
0.522
7
464.34
0.4513
1.166
8
474.92
0.8624
2.279
9
485.30
1.3444
3.631
10
495.64
1.8829
5.194
11
506.16
2.7060
7.623
the complete thermal history of this compound as the
precursor for CVD have been corroborated by the earlier
investigation [21] including its mass spectral study
confirming its molecular weight of 248Da. For a solid or
liquid compound to be really suitable for CVD, it should
exhibit thermal stability under a variety of ambient,
sufficient volatility and good gas phase transportability (visà-vis higher vapour pressure) [22, 23] for maintaining
adequate feed stock of the precursor.
In the present work, the vapour pressure measurement of
Ti(Cp)2Cl2 was carried out in the temperature range of 402485 K (129-212oC). The equilibrium vapour pressure (pe)
(Table 2) could be calculated using the following relation,
pe = WRT/MVc
(1)
derived from Dalton’s law of partial pressures for a mixture
of ideal gases, where W is the mass loss (mg) at temperature

5. Deposition of Ni/TiN Composite Coatings by a Plasma Assisted
Micro and Nanosystems, 2012, Vol. 4, No. 3
203
2.8
T (K)
402.18
412.44
422.82
433.21
443.54
454.01
464.34
474.92
485.30
485.64
506.16
2.4
Mass loss (mg)
2.0
1.6
1.2
0.8
0.4
0.0
0
10
20
30
40
50
60
Time (min)
Fig. (3). Plot of mass loss against isothermal time for each 1h holding during the vapour pressure measurement of Ti(Cp)2Cl2 compound.
2
R = 0.995
4.0
3.5
log pe
3.0
2.5
2.0
1.5
1.0
0.5
1.9
2.0
2.1
2.2
2.3
1000 K/T
2.4
2.5
2.6
Fig. (4). Clausius-Clapeyron plot for the Ti compound.
T(K) due to vapourisation, Vc (dm3) is the integral volume
of the carrier gas, R is the Gas constant (8.314 J mol-1 K-1)
and M (g mol-1) is the molar mass.
When the Eq. 1 is used, it is implied that only a single
metal precursor species is present in the vapour phase and
the congruent nature of vapourisation is confirmed by
TG/DTA under equilibrium condition. The monomeric
nature is confirmed by their mass spectral analysis [18].
Attainment of equilibrium conditions was evident from the
isothermal-time against mass loss plots (not exceeding 10%
of initial mass) at all the isothermal steps as seen from the
straight line plots (as shown in Fig. 3) passing through the
origin showing equal masses are vapourised in equal
intervals of time. The Clausius-Clapeyron plot of log (pe)
against the reciprocal temperature (1/T) is shown in Fig. (4).
The temperature dependence of pe could be represented
by the least squares expressions
log (pe/Pa) =(15.23±1.27)(A)–(5704.7±53.7)(B)/T(K) (402506 K)
(2)
Multiplying the slope (B) of the equation 2 by –2.303 R,
a value of 109.2 ± 5.6 kJ mol-1 could be derived for the
standard enthalpy of sublimation,
Hosub for the Ti
compound. A higher entropy of vapourisation and lower
enthalpy of sublimation would both contribute to higher
vapour pressure (e.g., pe = 7.62 Pa at 506 K) at constant
temperature as observed in the present investigation. The
higher value of sublimation enthalpy is an indicative of
moderate sublimation/volatilisation behaviour of any
compound. The sublimation studies are restricted to a
maximum temperature of 233oC (506 K). This restriction
stems from the fact that the values of pe approach the upper
periphery of applicability of the TG-based transpiration
technique which could not be fit into the linear regression
equation plot. The restriction in the temperature for both

6. 204 Micro and Nanosystems, 2012, Vol. 4, No. 3
Arockiasamy et al.
15
2
Intensity
10
0
T (2 0
iN 0 )
7
5
N (2 0
i 0)
5
0
T (4 0
iN 0 )
T (3 1
iN 1 )
N (3 1
i 1)
2
5
0
4
0
6
0
8
0
10
0
2th ta
e
Fig. (5). XRD pattern of Ni/TiN thin-film deposited on Si (100) substrate at 550oC; For TiN: JCPDS 381420 and Ni: JCPDS 040850.
Fig. (6). GIXRD of Ni/TiN thin film deposited at 550oC on Si (100) substrate.
vapour pressure measurement and for the deposition of films
by heating Ti(Cp)2Cl2 well below 280oC was also evident
from the fact that the complex releases HCl in the vapour
phase beyond 290oC [21].
3.2. Characterisation of Ni/TiN Thin Film
The conventional XRD and GIXRD patterns of Ni/TiN
composite thin film deposited under nitrogen plasma at a
substrate temperature of 550oC are shown in Figs. (5 and 6),
respectively, which reveal the crystalline film structure
indicated by the strong reflections from fcc phases TiN and
Ni. Both the patterns indicated the preferred orientation for
(200) reflection. Since the thickness of the films is ~500 nm,
we could not see any reflection from the substrate. Since
GIXRD could probe the surface of the film better, additional
peaks from metallic Ti was also seen. The observation of
TiN (200) textured orientation in the present investigation
could be due to the deposition of thin-films with higher
energy (but low temperature) produced by the electrons of
the plasma. This observation was corroborated by the
predominant formation of (200) orientation than (111) for
TiN, when deposited using ammonia and nitrogen plasma by
Weber et al. [24]. It is reported [25] that the microstructure
of Ni/TiN coatings deposited by magnetron sputtering has a
strong dependency for a bias voltage. At the higher bias
voltage (higher energy), there was a more rapid change of
orientation from (111) to (220) for TiN [25].
The size of the crystallite of Ni and TiN in the composite
Ni/TiN film was evaluated from the full width at half
maxima of the TiN (200) and Ni(200) peaks of the X-ray
diffraction using the Debye-Scherrer formula (D =
is the
0.9 / cos B, where D is size of the crystallite,
wavelength of the radiation used (in the present case CuK
of
= 0.15418 nm),
is the full width at half maxima
(FWHM) of the peak measured at the Bragg angle, B). It
must be noted that the calculation of crystallite size did not
take instrumental broadening and strain into consideration.
The Ni/TiN thin film deposited at 550 °C (Fig. 5) showed
crystallite sizes of 12.1nm for TiN(200) and 15.5 for
Ni(200).

7. Deposition of Ni/TiN Composite Coatings by a Plasma Assisted
Micro and Nanosystems, 2012, Vol. 4, No. 3
205
Fig. (7). SEM picture of Ni/TiN thin-film deposited at 550oC on Si(100) substrate in N2 plasma.
Fig. (8). EDX spectrum of Ni/TiN thin-film deposited at 550oC on Si (100) substrate.
The surface morphology and microstructure of thin films
depend closely on the deposition kinetics and substrate
temperature. The composite thin films of Ni/TiN were
analysed for their microstructure using SEM and EDX and
are shown in Figs. (7 and 8), respectively. The
microstructure analysis of the thin film confirms the densely
packed particles when deposited using high energy plasma at
550oC. It also reveals the nano-crystalline Ni/TiN grains
which are aggregated significantly. The EDX spectrum of the
composite film confirmed the chemical composition of the
thin films due to Ti, Ni and N only. Contamination of Cl in
the films was not noticed since the temperature of the
precursor chamber was maintained at about 290oC, a
temperature at which the compound could release HCl
vapour [21].
(a
linear
perfluoropolyalkylether
(PFPAE),
CF3O[CF2 CF2O]n-[CF2O]m-CF3; n/m=1.5) is a candidate oil
which can be operated at higher temperature, of 370oC [26],
but it chemically reacts with steel surfaces causing corrosion.
While surface chemistry controls the reactions between
PFPAE and TiN or Ni/TiN, the coating microstructure is also
extremely important for determining its protective capability.
A porous coating with columnar microstructure would
provide little protection [25]; fluid could penetrate the steel
surface and cause corrosion. A fully dense composite coating
with fine-grained microstructure would be the best to prevent
fluid penetration. Hence, the deposition of composite thinfilms using high energy plasma, which could enhance the
corrosion resistance nature of TiN has great industrial
importance.
The TiN hard coating is resistant to chemicals and is used
in aerospace turbine engines. Aircraft engines can be made
more efficient by operating at higher temperature. Fomblin Z
It must also mentioned that the strength and hardness of
the TiN thin-film could be increased by forming two-phase
nanostructure or multilayer thin-films, which help in

8. 206 Micro and Nanosystems, 2012, Vol. 4, No. 3
restricting the movement of dislocations. In multilayers,
dislocations are prevented from crossing from one layer to
the next by interfaces at layer thicknesses below a few nm
due to Kohler effect [27-31], which states that the dislocation
occurs from layers with higher elastic modulus at a layer
thickness below 10 nm [29, 30] or by a field of coherent
compressive/tensile stress originating from lattice
mismatches at layer thickness below 5 nm [30]. These
concepts were employed to increase hardness and toughness,
which was achieved in so-called super modulus [32] and
super lattice [33] multilayer coatings. Though no
nanomechanical properties have been reported in the present
work, it is proposed that the nanocomposite materials such as
Ni/TiN could be designed through the plasma assisted CVD
technique to create super hard coatings [34, 35]. Though
such coatings have been in practice by magnetron sputtering,
the present work provides a means to coat on objects with
irregular geometries and holes.
4. CONCLUSIONS
1.
2.
The Ni/TiN nanocomposite thin film deposited by
PAOMCVD showed the formation of fcc structured
TiN and Ni with (200) as the preferred orientation.
In the present investigation Ni/TiN film of about ~500
nm are obtained using the oxygen free precursor,
titanocene dichloride by using N2 plasma. This could
be ascribed to the efficiency of the plasma, in,
enhancing molecular dissociation and producing free
radicals to stimulate the chemical reactions in the
CVD chamber.
Arockiasamy et al.
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
3.
The particle sizes of the Ni and TiN in the thin film
are found to be 15.5 and 12.1 nm respectively.
[15]
4.
The titanium and nickel complexes exhibited
good/sufficient volatility to be used as precursors for
MO(OM)CVD. The titanium compound Ti(Cp)2Cl2
o
which was stable up to a temperature of 191 C with a
weight loss of about only 3% yielded a value of 109.2
± 5.6 kJ mol-1 for the standard enthalpy of sublimation
by a TG-based transpiration method.
[16]
[17]
CONFLICT OF INTEREST
The author confirms that this article content has no
conflicts of interest.
[18]
[19]
ACKNOWLEDGEMENT
Declared none.
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