The Raman spectra, X-ray diffraction and hardness of the TiAlN films co-deposited on the steel substrates
by reactive sputtering from Ti and Al targets in a mixture of N2 + Ar gas with two magnetrons at
room temperature have been studied. From Raman spectra it is found that the position of high-frequency
bands in vibrational spectra was located at 700-730 cm 1 or in the region of 830 850 cm 1 depending on
the deposition parameters whereas it is not exceed 630 cm 1 from TiAlN of NaCl structure. It is found the
two-phase structure of coatings: a small quantity of NaCl-type structure of TiAlN (TiN) and the disordered
structure of the chains of polyhedra [TiNx] with x = 5 and x = 4. The chains of polyhedra [TiNx] with x = 4
are mainly formed at large discharge power of Al(Ti) target or at small content of N2 gas.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2492

Blank, V.D.

Denisov, V.N.

Fernandez, A.

Godinho, V.

Gogolinsky, K.V.

Kirichenko, A.N.

Mavrin, B.N.

Philippon, D.

Polyakov, S.N.

Useinov, A.S.

Vinogradov, E.A.

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 4 No 1, 01021(4pp) (2012) Том 4 № 1, 01021(4cc) (2012)   2077-6772/2012/4(1)01021(4) 01021-1  2012 Sumy State University Structure of TiAlN Reactive Sputtered Coatings  V.N. Denisov1,2,*, B.N. Mavrin,2, E.A. Vinogradov2, S.N. Polyakov1, A.N. Kirichenko1, K.V. Gogolinsky1, A.S. Useinov1, V.D.  Blank1, V. Godinho3,4, D. Philippon3, A. Fernandez3  1 Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Moscow region, 142190 Russia 2 Institute of Spectroscopy of RAS, Troitsk, Moscow region, Phizicheskaya street 5, 142190 Russia 3 Instituto de Ciencia de Materiales de Sevilla CSIC-US Avenida Americo Vespucio 49, 41092 Sevilla, Spain 4 Université Libre de Bruxelles Faculty of Applied Sciences, Chemicals and Materials Department, Avenue F.D.Roosevelt, 50 (CP165/63) 1050 Brussels, Belgium  (Received 19 November 2011; published online 14 March 2012)  The Raman spectra, X-ray diffraction and hardness of the TiAlN films co-deposited on the steel sub-strates by reactive sputtering from Ti and Al targets in a mixture of N2 + Ar gas with two magnetrons at room temperature have been studied. From Raman spectra it is found that the position of high-frequency bands in vibrational spectra was located at 700-730 cm 1 or in the region of 830  850 cm 1 depending on the deposition parameters whereas it is not exceed 630 cm 1 from TiAlN of NaCl  structure. It is found the two-phase structure of coatings: a small quantity of NaCl-type structure of TiAlN (TiN) and the disordered structure of the chains of polyhedra [TiNx] with x = 5 and x = 4. The chains of polyhedra [TiNx] with x = 4 are mainly formed at large discharge power of Al(Ti) target or at small content of N2 gas.  Keywords: Coating, Hardness, Reactive Sputtering, TiAlN, X-Ray Diffraction, Raman Spectroscopy.   PACS numbers: 62.20.F, 62.20 – x, 78.30Ly, 78.30. – j, 61.05.C, 61.05.cp   ______________ * denisovvn@ntcstm.troitsk.ru  1. INTRODUCTION  Titanium-aluminium nitrides are technologically im-portant for different application fields such as wear-resistant and optical coatings. The TiAlN coatings find a continuously interest due to its high hardness, wear re-sistance and low oxidation rates. TiN is a NaCl-structure and it has metallic conductivity at room tempera-ture [1, 2]. AlN is crystallized in a wurtzite structure (w-AlN) and it may form the metastable rocksalt structure at high pressure [3]. The hardness of TiN is 21.6 GPa, while that of AlN is only 12.3 GPa [4]. Due to the structural refinement of TiAlN alloy the addition of Al atoms in TiN improves its hardness and the high-temperature oxida-tion resistance. However, for higher Al concentration the formation of w-AlN, which is softer than fcc-TiAlN, results in a significant reduction of the film hardness. The structure of TiAlN coatings depends strongly on the deposition parameters, in particular, on the Ti/Al ratio, the discharge power, deposition gas, substrate temperature, etc. In this work a systematic study on the influence of deposition parameters on the structure of TiAlN coatings is presented. Raman spectra and X-ray diffraction of TiAlN coatings were earlier studied by other authors for the TiN/AlN superlattices [5], TiAlN alloys [6-9], TiAlN/CrN multi-layers [7] and TiAlN-Si3N4 nanocomposite [10]. In these works, [5-10] results are given for coatings prepared at fixed Ti/Al ratio, with substrate temperature above room temperature and at invariable content of N2 gas.  2. EXPERIMENTAL DETAILS   The TiAlN films were co-deposited on sputter cleaned steel substrates by reactive sputtering from pure Ti and pure Al targets (Kurt Lesker 99.99 %) in a mixture of N2+Ar gas. Deposition was performed in a vacuum chamber equipped with two magnetrons driven by dc power. Table 1 summarizes the deposition conditions. Table 1 – Deposition conditions  №   1 Base pressure 10 4 Pa 2 Target substrate distance 10 cm 3 Substrate cleaning 400V at 7Pa Ar for 15 min 4 Target cleaning 600W at 7Pa Ar for 15 min 5 Power supply (Ti, Al ) 200—600 W d.c 6 Sputtering gas %N2/(N2+Ar)  15, 30, 70% 7 Deposition time 5-150 min  The power supplied to the two targets varied from 200 to 600 W and different gas mixtures were used in order to obtain coatings with different composition. The composition of the coatings was evaluated by XPS (not presented here), the Ti1-xAlxN present compositions ranging from x  0.07 to 0.60. The effect of deposition time on the structure of the TiAlN films was also inves-tigated. For thick coatings, a TiAl adhesion layer was deposited prior to the coating. The microstructure of the coatings was investigated by XRD. The XRD measurements were performed in the Rigaku D / max-RC equipped with a 12 kW X-ray source with a rotary anode using monochromatic Cu Kα radiation and the graphite crystal-analyser. The graz-ing incidence asymmetrical Bragg  diffraction (GIABD) with the parallel beam optics was employed for phase composition and chemical homogeneity investigations. Incidence angles of 1 and 0.5 were used. The Raman spectra were excited with the line at 514.5 nm of an Ar-laser. The spectrograph TRIAX 552 with special corrective optics, the Notch filters and CCD camera were used for the investigation of the Raman scattering light. The spectral resolution was about 3 cm 1. We have used the setup of micro-Raman spectroscopy with a microscope which provided a focus diameter in the micrometer range and a large scatter- V.N. DENISOV, B.N. MAVRIN, E.A. VINOGRADOV… J. NANO- ELECTRON. PHYS. 4, 01021 (2012)   01021-2 ing collection angle. The mechanical properties and surface topography were investigated using the scan-ning nano-hardness tester NanoScan  3D. The hard-ness and elastic modulus values were measured with the instrumented nanoindentation test according to ISO 14577.  3. RESULTS AND DISCUSSION   3.1 X-Ray Diffractometry  Figure 1 presents the X-ray diffraction pattern for samples deposited under different power rate and dep-osition times resulting in different thicnkess. Peak po-sitions for reference compounds of c TiN and c TiAlN are marked.     a   b Fig. 1 – X-ray diffraction patterns for samples prepared at dif-ferent power rate and deposition times: thinner coatings, inci-dence angle of 0.5º(a); thicker coatings, incidence angle of 1º(b)  A part from substrate peaks, NaCl type of (TiAl)N (non stoichiometric) diffraction peaks can be identified as well. In both cases thinner and thicker coatings, the in-crease in Ti power results in an increase of crystallinity of the coating, and the preferential orientation changes from (111) to (200). When the power in the Al target is in-creased to 600 W the coating becomes more amorphous.  3.2 Raman Spectroscopy  Raman spectra of obtained TiAlN  coatings are pre-sented at Figures 2-7. A narrow band at 520 cm 1 was seen in the Raman spectra from TiAlN  thin coatings (≤ 100 nm) (Fig. 2). It disappeared gradually as the coating thickness increased. We assign it to the Raman scattering from the substrate. Apart from this narrow band only the broad bands were observed in the Raman spectra from TiAlN coatings (Fig. 2-7). Depending on the deposition process the position of high-frequency band in the Raman spectra was about 700 cm 1 or in the region of 830-850 cm 1. When the bands at 830-850 cm 1 were present in the spectrum, the broad bands in the region of 600-630 cm 1 also appeared and these two regions of the broad bands have formed the poorly structured background due to the overlapping (Fig. 2-7).    Fig. 2  Raman spectra of TiAlN coatings at Ti discharge power of 200 W  and 15%N2. Where 1 – 200 W Al, 2  400 W Al,  3 – 600 W Al  It is known [1] that the Raman bands of TiN are due to a contribution of the phonon density of states from the acoustic modes (225 (TA) and 310 (LA) cm 1) and the optic modes (540 cm 1). When Al atoms are  added to TiN lattice the structure of NaCl-type is maintained and Ti atoms are substituted by Al atoms [11]. As in the case of TiN-NbN [8], TiAlN-CrN [7] and CrAlN [12], we believe that the Raman bands in the spectra from TiAlN alloys are assigned to vibrations of Ti-N bonds, and the influence of Al doping is displayed in a high-frequency shift of optic modes of TiN. The stress in coatings may also lead to the high-frequency shift of bands in spectra. Therefore we assign the Ra-man bands in the region of 600  630 cm 1 to the optic vibrations of Ti N bond in TiAlN coatings with a NaCl-structure. An appearance of broad bands in the regions of 700-730 and 830-850 cm 1 can not be explained by a substi-tution of Ti atoms by Al atoms in the structure of NaCl-type. Supposing the assignment of these bands to vi-brations of Ti-N bonds, the significant rise of their fre-quencies may be due to the break of NaCl-type of TiN structure and the formation of the disordered structure with the chains of polyhedra [TiNx] with the less num-ber of N atoms around Ti than 6. It is known that the vibrational frequency is increased with a decrease of the coordination number. Therefore one can assume that the bands at 700-730 cm 1 correspond to chains with x  5 and at 830-850 cm 1 to chains with x  4. At first we shall consider the Raman spectra from TiAlN coatings produced at the constant ration Ti/Al and at the increase of discharge power (Fig. 2). If the position of the high-frequency band is near 700 cm 1 and the intensity of acoustic and optic bands are com-parable at 200 W discharge power, then two bands at 610 and 840 cm 1 and the essential rise of the intensity 20 30 40 50 60 70 80substrate  200W Ti-200W Al (1200nm)  200W Ti-600W Al (3700nm)    Intensity (arb. units)Diffraction angle 2400W Ti-200W Al (4500nm)  (Ti,Al)N (311)TiN (311)(Ti,Al)N (220)TiN (220)(Ti,Al)N (200)TiN (200)(Ti,Al)N (111)TiN (111)TiN (222)(Ti,Al)N (100) 20 30 40 50 60 70 80Diffraction angle 2  Intensity (arb. units)(Ti,Al)N (220)TiN (111)substrate  200W Ti-200W Al (50nm)  200W Ti-600W Al (200nm)    400W Ti-200W Al (200nm)  (Ti,Al)N (311)TiN (311)(Ti,Al)N (220)TiN (220)(Ti,Al)N (200)TiN (200)(Ti,Al)N (111)TiN (111)TiN (222)(Ti,Al)N (100) STRUCTURE OF TIALN REACTIVE SPUTTERED COATINGS J. NANO- ELECTRON. PHYS. 4, 01021 (2012)   01021-3 of acoustic modes may be seen in the Raman spectra from coatings produced at 400 and 600 W power. Note the band at 700 cm 1 is overlapped with the broad band at 610 cm 1. One can assume two-phase composition of coatings produced at all powers: TiAlN of NaCl-structure (the band at 610 cm 1) and a phase with chains of [TiNx] polyhedra with x = 5 (the band at 700 cm 1) and  x = 4 (the band at 840 cm 1). In Fig. 2, as in Fig. 3 and 4, the Raman spectra are shown for coat-ings of approximately similar thickness.  In the Raman spectra from TiAlN coatings prepared at fixed Ti power (200 W) and at various Al powers (Fig. 3) one can see also two-phase structure and the quantity of the NaCl-structure of TiAlN is decreased with the increase of Al power.    Fig. 3   Raman spectra of Ti0.5Al0.5N coatings at various Al and Ti discharge power and 15 N2. Where 1 – 200 W Al, 200 W Ti, 2 – 400 W Al, 400 W Ti, 3 – 600 W Al, 600 W Ti  Besides the type of chains changes from x = 5 to x = 4, two-phase structure of TiAlN coatings produced at fixed Al power is also formed with the increase of Ti power (Fig. 4). Fig. 5 shows the transformation of the Raman spec-tra from TiAlN coatings prepared at various content of N2 gas. The position of the high-frequency band is equal to 700 cm 1 at 70 % N2 and 730 cm 1 at 30 % N2. But two bands at 590 and 840 cm 1 and the noticeable increase of the intensity of acoustic modes are seen at 15 % N2. We assume that the two-phase structure of TiAlN coating is formed at 15 % N2.    Fig. 4  Raman spectra of TiAlN coatings at Al discharge power of 200 W and 15%N2 and various Ti discharge power. Where 1  200 W Ti and thickness 125 nm, 2  400 W Ti and thickness 205 nm   Fig. 5   Raman spectra of TiAlN coatings at equal Ti/Al ratio and various N2 content. Ti and Al discharge power is 400 W. 1  15% N2, 2  30% N2, 3  70%N2.  Most likely, two-phase structure with predominant content of chains [TiN5] is formed in TiAlN coatings pre-pared at 200 W Ti – 200 W Al power for thicknesses from 52 to 1200 nm (Fig. 6). One can see in the Raman spectra that the signal / noise ratio is higher in the coat-ing of 52 nm thickness than for thicker coatings. Be-sides, the band at 730 cm 1 in the thin coating is more distinct than in the spectra from the thick coatings. One can assume that the TiAlN alloys that is con-tiguous to the substrate is not only more homogeneous, but also it gives the resonance enhancement of the Raman intensity due to a change of electronic structure of TiN at Al doping or the electromagnetic enhance-ment on the metal-film boundary. It should be noted that the Fermi level in TiAlN alloys of NaCl  structure moves progressively down from the conduction band to the band gap as the alloy composition is varied from metallic TiN to wide-gap semiconductor AlN.    Fig. 6   Raman spectra of TiAlN coatings at ratio Ti / Al = 1 and various thickness of coating. Ti and Al discharge power is 200 W, 15 % N2. Thickness is: 1 – 52 nm, 2 – 100 nm, 3 – 125 nm, 4 – 1200 nm  The increase of the coating thickness doesn’t lead also to the essential transformation of its structure at the ratio Al / Ti  1 that one can see from the spectra for coatings with the ratio Al / Ti = 3 (Fig. 7). However, the spectrum from the thick coating (3700 nm) was weaker and the high-frequency optic modes in the re-gion of  800 cm 1 are weak in comparison with the band at  600 cm 1.  V.N. DENISOV, B.N. MAVRIN, E.A. VINOGRADOV… J. NANO- ELECTRON. PHYS. 4, 01021 (2012)   01021-4   Fig. 7 – Raman spectra of TiAlN coatings at ratio Ti / Al = 1 / 3 (200 W on Ti, 600 W on Al target, 15 % N2) and various thick-ness of coatings. 1 – 3700 nm, 2 – 180 nm, 3  90 nm  3.3 Nano-Hardness Tests  Young module E, hardness H and elastic modulus R under loading P and thickness of coatings h are given in Table 2.  Table 2 – NanoScan3D test results.  Coating prepara-tion condition P, mN h, nm E, GPa H, GPa R, % 200 WTi  200 W Al, 15 % N2 1 80 118 5.1 40 400WTi  400W Al, 70 % N2 2 90 172 8.9 52 200WTi  400W Al, 30 % N2 2 130 114 4.4 36 400WTi  200W Al, 15 % N2 5 190 146 5.4 35 200WTi  600W Al, 15 % N2 5 140 150 12.1 45 Our results are in agreement with the hardness ob-tained for TiAlN coatings deposited on substrates at 22 oC [13].  4. CONCLUSIONS   The investigations of Raman spectra and X-ray dif-fraction of TiAlN coatings on the steel substrates de-posited at room temperature allow us to find the struc-tural transformation of coatings in dependence on the deposition process. XRD has shown multiphase compo-sition of coatings. The different structures of coatings were displayed in the position of high-frequency Ra-man bands in the region > 500 cm 1. It is assumed that  the Raman band at 600-630 cm 1 corresponds to a NaCl  structure of TiAlN alloy and the appearance of Raman broad bands above 630 cm 1 could be due to a formation of chains of polyhedra [TiNx] with x = 4 or 5. It was shown two-phase structure of coatings: a small quantity of NaCl  structure and the disordered struc-ture of chains [TiNx] with x = 4 or 5. The chains of pol-yhedra [TiNx] with x = 4 are mainly formed at  large discharge power of Al(Ti) target or at small content of N2 gas.   ACKNOWLEDGEMENTS  Authors thank the financial support from EC (pro-ject NOE EXCELL), Spanish Ministry MICINN (CONSOLIDER FUNCOAT) and Junta de Andalucia.    REFERENCES  1. W. Sprengler, R. Kaiser, A.N. Christiansen, G. Müller-Fogt, S. Veprek, Phys. Rev. B. 17, 1095 (1978). 2. B.O. Johanson, J.-E. Sundgren, J.E. Greene, A. Rockett, S.A. Barnett, J. Vac. Sci. Technol. A3, 303 (1985). 3. Q.  Xia, H. Xia, A.L. Ruoff, J. Appl. Phys. 73, 8198 (1993). 4.  CRC Materials Science and Engineering Handbook, (Ed. J.F. Shackelford, W. Alexander, J.S. Park) (Boca Ra-ton: CRC Press: 1994). 5. M. Bernard, A. Deneuville, O. Thomas, P. Gergaud, P. Sandstrom, J. Birch, Thin Solid Films 380, 252 (2000). 6. C.P. Constable, J. Yarwood, W.-D. Münz, Surf. Coat. Tech. 116, 155 (1999). 7. H.C. Barshilia, K.S. Rajam, J. Mater. Res. 19, 3196 (2004). 8. H.C. Barshilia, K.S. Rajam, J. Appl. Phys. 98, 014311 (2005).  9. B. Subramanian, K. Ashok, P. Kuppusami, C. Sanjeeviraja, M. Jayachandran, Cryst. Res. Technol. 43, 1078 (2008). 10. H.C. Barshilia, B. Deepthi, K.S. Rajam, Vacuum 81, 479 (2006). 11. V. Podgursky, B. Torp, R. Traksmaa, R. Veinthal, M. Viljus, O. Coddet, M. Morstein, A. Gregor, P. Kulu, Material Science (Medžiagotyra). 11, 352 (2005). 12. H.C. Barshilia, N. Selvakumar, B. Deepthi, K.S. Rajam, Surf. Coat. Tech. 201, 2193 (2006). 13.  L. García-González, M. G. Garnica-Romo, J. Hernández-Torres, F. J. Espinoza-Beltrán, Braz. J. Chem. Eng. 24, 249 (2007).   

Structure of TiAlN Reactive Sputtered Coatings

Godinho, Vanda

Philippon, David

Fernández, Asuncion

HAL Descartes

The Raman spectra, X-ray diffraction and hardness of the TiAlN films co-deposited on the steel substrates by reactive sputtering from Ti and Al targets in a mixture of N 2 + Ar gas with two magnetrons at room temperature have been studied. From Raman spectra it is found that the position of high-frequency bands in vibrational spectra was located at 700-730 cm -1 or in the region of 830 - 850 cm -1 depending on the deposition parameters whereas it is not exceed 630 cm -1 from TiAlN of NaCl structure. It is found the two-phase structure of coatings: a small quantity of NaCl-type structure of TiAlN (TiN) and the disordered structure of the chains of polyhedra [TiN x] with x = 5 and x = 4. The chains of polyhedra [TiN x] with x = 4 are mainly formed at large discharge power of Al(Ti) target or at small content of N 2 gas

Mavrin, B.B.

Kiricjenko, A.N.

Fortio Godinho, Vanda Cristina

Fernández Camacho, Asunción

idUS. Depósito de Investigación Universidad de Sevilla

English

Structure of TiAlN reactive sputtered coatings

SocioEconomic Challenges Journal (Sumy State University)

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ 
Vol. 4 No 1, 01021(4pp) (2012) Том 4 № 1, 01021(4cc) (2012) 
 
 
2077-6772/2012/4(1)01021(4) 01021-1  2012 Sumy State University 
Structure of TiAlN Reactive Sputtered Coatings 
 
V.N. Denisov1,2,*, B.N. Mavrin,2, E.A. Vinogradov2, S.N. Polyakov1, A.N. Kirichenko1, K.V. Gogolinsky1, 
A.S. Useinov1, V.D.  Blank1, V. Godinho3,4, D. Philippon3, A. Fernandez3 
 
1 Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Moscow region, 142190 Russia 
2 Institute of Spectroscopy of RAS, Troitsk, Moscow region, Phizicheskaya street 5, 142190 Russia 
3 Instituto de Ciencia de Materiales de Sevilla CSIC-US Avenida Americo Vespucio 49, 41092 Sevilla, Spain 
4 Université Libre de Bruxelles Faculty of Applied Sciences, Chemicals and Materials Department, Avenue 
F.D.Roosevelt, 50 (CP165/63) 1050 Brussels, Belgium 
 
(Received 19 November 2011; published online 14 March 2012) 
 
The Raman spectra, X-ray diffraction and hardness of the TiAlN films co-deposited on the steel sub-
strates by reactive sputtering from Ti and Al targets in a mixture of N2 + Ar gas with two magnetrons at 
room temperature have been studied. From Raman spectra it is found that the position of high-frequency 
bands in vibrational spectra was located at 700-730 cm 1 or in the region of 830  850 cm 1 depending on 
the deposition parameters whereas it is not exceed 630 cm 1 from TiAlN of NaCl  structure. It is found the 
two-phase structure of coatings: a small quantity of NaCl-type structure of TiAlN (TiN) and the disordered 
structure of the chains of polyhedra [TiNx] with x = 5 and x = 4. The chains of polyhedra [TiNx] with x = 4 
are mainly formed at large discharge power of Al(Ti) target or at small content of N2 gas. 
 
Keywords: Coating, Hardness, Reactive Sputtering, TiAlN, X-Ray Diffraction, Raman Spectroscopy. 
 
 PACS numbers: 62.20.F, 62.20 – x, 78.30Ly, 78.30. – j, 61.05.C, 
61.05.cp 
 
 
______________ 
* denisovvn@ntcstm.troitsk.ru  
1. INTRODUCTION 
 
Titanium-aluminium nitrides are technologically im-
portant for different application fields such as wear-
resistant and optical coatings. The TiAlN coatings find a 
continuously interest due to its high hardness, wear re-
sistance and low oxidation rates. TiN is a NaCl-structure 
and it has metallic conductivity at room tempera-
ture [1, 2]. AlN is crystallized in a wurtzite structure (w-
AlN) and it may form the metastable rocksalt structure at 
high pressure [3]. The hardness of TiN is 21.6 GPa, while 
that of AlN is only 12.3 GPa [4]. Due to the structural 
refinement of TiAlN alloy the addition of Al atoms in TiN 
improves its hardness and the high-temperature oxida-
tion resistance. However, for higher Al concentration the 
formation of w-AlN, which is softer than fcc-TiAlN, results 
in a significant reduction of the film hardness. 
The structure of TiAlN coatings depends strongly on 
the deposition parameters, in particular, on the Ti/Al 
ratio, the discharge power, deposition gas, substrate 
temperature, etc. In this work a systematic study on the 
influence of deposition parameters on the structure of 
TiAlN coatings is presented. 
Raman spectra and X-ray diffraction of TiAlN coatings 
were earlier studied by other authors for the TiN/AlN 
superlattices [5], TiAlN alloys [6-9], TiAlN/CrN multi-
layers [7] and TiAlN-Si3N4 nanocomposite [10]. In these 
works, [5-10] results are given for coatings prepared at 
fixed Ti/Al ratio, with substrate temperature above room 
temperature and at invariable content of N2 gas. 
 
2. EXPERIMENTAL DETAILS  
 
The TiAlN films were co-deposited on sputter cleaned 
steel substrates by reactive sputtering from pure Ti and 
pure Al targets (Kurt Lesker 99.99 %) in a mixture of 
N2+Ar gas. Deposition was performed in a vacuum 
chamber equipped with two magnetrons driven by dc 
power. Table 1 summarizes the deposition conditions. 
Table 1 – Deposition conditions 
 
№   
1 Base pressure 10 4 Pa 
2 Target substrate distance 10 cm 
3 Substrate cleaning 400V at 7Pa Ar for 15 min 
4 Target cleaning 600W at 7Pa Ar for 15 min 
5 Power supply (Ti, Al ) 200—600 W d.c 
6 Sputtering gas %N2/(N2+Ar)  15, 30, 70% 
7 Deposition time 5-150 min 
 
The power supplied to the two targets varied from 
200 to 600 W and different gas mixtures were used in 
order to obtain coatings with different composition. The 
composition of the coatings was evaluated by XPS (not 
presented here), the Ti1-xAlxN present compositions 
ranging from x  0.07 to 0.60. The effect of deposition 
time on the structure of the TiAlN films was also inves-
tigated. For thick coatings, a TiAl adhesion layer was 
deposited prior to the coating. 
The microstructure of the coatings was investigated 
by XRD. The XRD measurements were performed in 
the Rigaku D / max-RC equipped with a 12 kW X-ray 
source with a rotary anode using monochromatic Cu Kα 
radiation and the graphite crystal-analyser. The graz-
ing incidence asymmetrical Bragg  diffraction (GIABD) 
with the parallel beam optics was employed for phase 
composition and chemical homogeneity investigations. 
Incidence angles of 1 and 0.5 were used. 
The Raman spectra were excited with the line at 
514.5 nm of an Ar-laser. The spectrograph TRIAX 552 
with special corrective optics, the Notch filters and 
CCD camera were used for the investigation of the 
Raman scattering light. The spectral resolution was 
about 3 cm 1. We have used the setup of micro-Raman 
spectroscopy with a microscope which provided a focus 
diameter in the micrometer range and a large scatter-
 V.N. DENISOV, B.N. MAVRIN, E.A. VINOGRADOV… J. NANO- ELECTRON. PHYS. 4, 01021 (2012) 
 
 
01021-2 
ing collection angle. The mechanical properties and 
surface topography were investigated using the scan-
ning nano-hardness tester NanoScan  3D. The hard-
ness and elastic modulus values were measured with 
the instrumented nanoindentation test according to 
ISO 14577. 
 
3. RESULTS AND DISCUSSION  
 
3.1 X-Ray Diffractometry 
 
Figure 1 presents the X-ray diffraction pattern for 
samples deposited under different power rate and dep-
osition times resulting in different thicnkess. Peak po-
sitions for reference compounds of c TiN and c TiAlN 
are marked.  
 
 
 a 
 
 b 
Fig. 1 – X-ray diffraction patterns for samples prepared at dif-
ferent power rate and deposition times: thinner coatings, inci-
dence angle of 0.5º(a); thicker coatings, incidence angle of 1º(b) 
 
A part from substrate peaks, NaCl type of (TiAl)N 
(non stoichiometric) diffraction peaks can be identified as 
well. In both cases thinner and thicker coatings, the in-
crease in Ti power results in an increase of crystallinity of 
the coating, and the preferential orientation changes from 
(111) to (200). When the power in the Al target is in-
creased to 600 W the coating becomes more amorphous. 
 
3.2 Raman Spectroscopy 
 
Raman spectra of obtained TiAlN  coatings are pre-
sented at Figures 2-7. A narrow band at 520 cm 1 was 
seen in the Raman spectra from TiAlN  thin coatings 
(≤ 100 nm) (Fig. 2). It disappeared gradually as the 
coating thickness increased. We assign it to the Raman 
scattering from the substrate. Apart from this narrow 
band only the broad bands were observed in the Raman 
spectra from TiAlN coatings (Fig. 2-7). Depending on 
the deposition process the position of high-frequency 
band in the Raman spectra was about 700 cm 1 or in 
the region of 830-850 cm 1. When the bands at 830-
850 cm 1 were present in the spectrum, the broad 
bands in the region of 600-630 cm 1 also appeared and 
these two regions of the broad bands have formed the 
poorly structured background due to the overlapping 
(Fig. 2-7). 
 
 
 
Fig. 2  Raman spectra of TiAlN coatings at Ti discharge power 
of 200 W  and 15%N2. Where 1 – 200 W Al, 2  400 W Al,  
3 – 600 W Al 
 
It is known [1] that the Raman bands of TiN are 
due to a contribution of the phonon density of states 
from the acoustic modes (225 (TA) and 310 (LA) cm 1) 
and the optic modes (540 cm 1). When Al atoms are 
 added to TiN lattice the structure of NaCl-type is 
maintained and Ti atoms are substituted by Al atoms 
[11]. As in the case of TiN-NbN [8], TiAlN-CrN [7] and 
CrAlN [12], we believe that the Raman bands in the 
spectra from TiAlN alloys are assigned to vibrations of 
Ti-N bonds, and the influence of Al doping is displayed 
in a high-frequency shift of optic modes of TiN. The 
stress in coatings may also lead to the high-frequency 
shift of bands in spectra. Therefore we assign the Ra-
man bands in the region of 600  630 cm 1 to the optic 
vibrations of Ti N bond in TiAlN coatings with a NaCl-
structure. 
An appearance of broad bands in the regions of 700-
730 and 830-850 cm 1 can not be explained by a substi-
tution of Ti atoms by Al atoms in the structure of NaCl-
type. Supposing the assignment of these bands to vi-
brations of Ti-N bonds, the significant rise of their fre-
quencies may be due to the break of NaCl-type of TiN 
structure and the formation of the disordered structure 
with the chains of polyhedra [TiNx] with the less num-
ber of N atoms around Ti than 6. It is known that the 
vibrational frequency is increased with a decrease of 
the coordination number. Therefore one can assume 
that the bands at 700-730 cm 1 correspond to chains 
with x  5 and at 830-850 cm 1 to chains with x  4. 
At first we shall consider the Raman spectra from 
TiAlN coatings produced at the constant ration Ti/Al 
and at the increase of discharge power (Fig. 2). If the 
position of the high-frequency band is near 700 cm 1 
and the intensity of acoustic and optic bands are com-
parable at 200 W discharge power, then two bands at 
610 and 840 cm 1 and the essential rise of the intensity 
20 30 40 50 60 70 80
substrate  
200W Ti-200W Al (1200nm)  
200W Ti-600W Al (3700nm)  
 
 
In
te
n
s
it
y
 (
a
rb
. 
u
n
it
s
)
Diffraction angle 2
400W Ti-200W Al (4500nm)  
(T
i,
A
l)
N
 (
3
1
1
)
T
iN
 (
3
1
1
)
(T
i,
A
l)
N
 (
2
2
0
)
T
iN
 (
2
2
0
)
(T
i,
A
l)
N
 (
2
0
0
)
T
iN
 (
2
0
0
)
(T
i,
A
l)
N
 (
1
1
1
)
T
iN
 (
1
1
1
)
T
iN
 (
2
2
2
)
(T
i,
A
l)
N
 (
1
0
0
)
 
20 30 40 50 60 70 80
Diffraction angle 2
 
 
In
te
n
s
it
y
 (
a
rb
. 
u
n
it
s
)
(T
i,
A
l)
N
 (
2
2
0
)
T
iN
 (
1
1
1
)
substrate  
200W Ti-200W Al (50nm)  
200W Ti-600W Al (200nm)   
 
400W Ti-200W Al (200nm)  
(T
i,
A
l)
N
 (
3
1
1
)
T
iN
 (
3
1
1
)
(T
i,
A
l)
N
 (
2
2
0
)
T
iN
 (
2
2
0
)
(T
i,
A
l)
N
 (
2
0
0
)
T
iN
 (
2
0
0
)
(T
i,
A
l)
N
 (
1
1
1
)
T
iN
 (
1
1
1
)
T
iN
 (
2
2
2
)
(T
i,
A
l)
N
 (
1
0
0
)
 STRUCTURE OF TIALN REACTIVE SPUTTERED COATINGS J. NANO- ELECTRON. PHYS. 4, 01021 (2012) 
 
 
01021-3 
of acoustic modes may be seen in the Raman spectra 
from coatings produced at 400 and 600 W power. Note 
the band at 700 cm 1 is overlapped with the broad band 
at 610 cm 1. One can assume two-phase composition of 
coatings produced at all powers: TiAlN of NaCl-
structure (the band at 610 cm 1) and a phase with 
chains of [TiNx] polyhedra with x = 5 (the band at 
700 cm 1) and  x = 4 (the band at 840 cm 1). In Fig. 2, as 
in Fig. 3 and 4, the Raman spectra are shown for coat-
ings of approximately similar thickness.  
In the Raman spectra from TiAlN coatings prepared 
at fixed Ti power (200 W) and at various Al powers 
(Fig. 3) one can see also two-phase structure and the 
quantity of the NaCl-structure of TiAlN is decreased 
with the increase of Al power. 
 
 
 
Fig. 3   Raman spectra of Ti0.5Al0.5N coatings at various Al 
and Ti discharge power and 15 N2. Where 1 – 200 W Al, 
200 W Ti, 2 – 400 W Al, 400 W Ti, 3 – 600 W Al, 600 W Ti 
 
Besides the type of chains changes from x = 5 to 
x = 4, two-phase structure of TiAlN coatings produced 
at fixed Al power is also formed with the increase of Ti 
power (Fig. 4). 
Fig. 5 shows the transformation of the Raman spec-
tra from TiAlN coatings prepared at various content of 
N2 gas. The position of the high-frequency band is 
equal to 700 cm 1 at 70 % N2 and 730 cm 1 at 30 % N2. 
But two bands at 590 and 840 cm 1 and the noticeable 
increase of the intensity of acoustic modes are seen at 
15 % N2. We assume that the two-phase structure of 
TiAlN coating is formed at 15 % N2. 
 
 
 
Fig. 4  Raman spectra of TiAlN coatings at Al discharge 
power of 200 W and 15%N2 and various Ti discharge power. 
Where 1  200 W Ti and thickness 125 nm, 2  400 W Ti and 
thickness 205 nm 
 
 
Fig. 5   Raman spectra of TiAlN coatings at equal Ti/Al ratio 
and various N2 content. Ti and Al discharge power is 400 W. 
1  15% N2, 2  30% N2, 3  70%N2. 
 
Most likely, two-phase structure with predominant 
content of chains [TiN5] is formed in TiAlN coatings pre-
pared at 200 W Ti – 200 W Al power for thicknesses 
from 52 to 1200 nm (Fig. 6). One can see in the Raman 
spectra that the signal / noise ratio is higher in the coat-
ing of 52 nm thickness than for thicker coatings. Be-
sides, the band at 730 cm 1 in the thin coating is more 
distinct than in the spectra from the thick coatings. 
One can assume that the TiAlN alloys that is con-
tiguous to the substrate is not only more homogeneous, 
but also it gives the resonance enhancement of the 
Raman intensity due to a change of electronic structure 
of TiN at Al doping or the electromagnetic enhance-
ment on the metal-film boundary. It should be noted 
that the Fermi level in TiAlN alloys of NaCl  structure 
moves progressively down from the conduction band to 
the band gap as the alloy composition is varied from 
metallic TiN to wide-gap semiconductor AlN. 
 
 
 
Fig. 6   Raman spectra of TiAlN coatings at ratio Ti / Al = 1 
and various thickness of coating. Ti and Al discharge power is 
200 W, 15 % N2. Thickness is: 1 – 52 nm, 2 – 100 nm, 3 –
 125 nm, 4 – 1200 nm 
 
The increase of the coating thickness doesn’t lead 
also to the essential transformation of its structure at 
the ratio Al / Ti  1 that one can see from the spectra 
for coatings with the ratio Al / Ti = 3 (Fig. 7). However, 
the spectrum from the thick coating (3700 nm) was 
weaker and the high-frequency optic modes in the re-
gion of  800 cm 1 are weak in comparison with the 
band at  600 cm 1. 
 V.N. DENISOV, B.N. MAVRIN, E.A. VINOGRADOV… J. NANO- ELECTRON. PHYS. 4, 01021 (2012) 
 
 
01021-4 
 
 
Fig. 7 – Raman spectra of TiAlN coatings at ratio Ti / Al = 1 / 3 
(200 W on Ti, 600 W on Al target, 15 % N2) and various thick-
ness of coatings. 1 – 3700 nm, 2 – 180 nm, 3  90 nm 
 
3.3 Nano-Hardness Tests 
 
Young module E, hardness H and elastic modulus R 
under loading P and thickness of coatings h are given 
in Table 2. 
 
Table 2 – NanoScan3D test results. 
 
Coating prepara-
tion condition 
P, mN h, nm E, GPa 
H, 
GPa 
R, 
% 
200 WTi  200 W 
Al, 15 % N2 
1 80 118 5.1 40 
400WTi  400W 
Al, 70 % N2 
2 90 172 8.9 52 
200WTi  400W 
Al, 30 % N2 
2 130 114 4.4 36 
400WTi  200W 
Al, 15 % N2 
5 190 146 5.4 35 
200WTi  600W 
Al, 15 % N2 
5 140 150 12.1 45 
Our results are in agreement with the hardness ob-
tained for TiAlN coatings deposited on substrates at 
22 oC [13]. 
 
4. CONCLUSIONS  
 
The investigations of Raman spectra and X-ray dif-
fraction of TiAlN coatings on the steel substrates de-
posited at room temperature allow us to find the struc-
tural transformation of coatings in dependence on the 
deposition process. XRD has shown multiphase compo-
sition of coatings. The different structures of coatings 
were displayed in the position of high-frequency Ra-
man bands in the region > 500 cm 1. It is assumed that  
the Raman band at 600-630 cm 1 corresponds to a 
NaCl  structure of TiAlN alloy and the appearance of 
Raman broad bands above 630 cm 1 could be due to a 
formation of chains of polyhedra [TiNx] with x = 4 or 5. 
It was shown two-phase structure of coatings: a small 
quantity of NaCl  structure and the disordered struc-
ture of chains [TiNx] with x = 4 or 5. The chains of pol-
yhedra [TiNx] with x = 4 are mainly formed at  large 
discharge power of Al(Ti) target or at small content of 
N2 gas.  
 
ACKNOWLEDGEMENTS 
 
Authors thank the financial support from EC (pro-
ject NOE EXCELL), Spanish Ministry MICINN 
(CONSOLIDER FUNCOAT) and Junta de Andalucia. 
 
 
 
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