Journal of Alloys and Compounds 546 (2013) 280–285

Contents lists available at SciVerse ScienceDirect

Journal of Alloys and Compounds

journal homepage: www.elsevier .com/locate / ja lcom

Studies of the hot-pressed TiN material by electron spectroscopies

Mirosław Krawczyk ⇑, Wojciech Lisowski, Janusz W. Sobczak, Andrzej Kosinski, Aleksander JablonskiInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland

a r t i c l e i n f o a b s t r a c t

Article history:Received 23 June 2012Received in revised form 21 August 2012Accepted 22 August 2012Available online 31 August 2012

Keywords:Hot-pressed sputtering targetTitanium nitrideX-ray photoelectron spectroscopyElastic-peak electron spectroscopySurface compositionBulk compositionElectron inelastic mean free path

0925-8388/$ - see front matter � 2012 Elsevier B.V. Ahttp://dx.doi.org/10.1016/j.jallcom.2012.08.089

⇑ Corresponding author. Tel.: +48 22 3433403; fax:E-mail address: mkrawczyk@ichf.edu.pl (M. Krawc

We analyzed chemical composition and electron transport phenomena in surface and sub-surface regionof hot-pressed TiN specimens using a combination of X-ray photoelectron spectroscopy (XPS) and elastic-peak electron spectroscopy (EPES) techniques. Both the surface chemical composition and the elementsdistribution in the bulk of TiN specimens were determined using XPS and XPS depth profiling analysis. Inaddition to TiN, a mixture of Ti oxynitride (TiOxNy) and TiO2 compounds as well as carbon contaminantshave been detected in the surface region of the TiN specimens. The elemental depth-profiles discloseduniform chemical bulk composition formed mainly by titanium and nitrogen as well as carbon and oxy-gen contaminants. Surface enrichment of Ti was evidenced as result of Ar ion-induced preferential sput-tering of nitrogen. The inelastic mean free path (IMFP) data evaluated from the relative EPES for electronenergies 0.5–2 keV were uncorrected for surface excitations and compared with those calculated fromthe predictive TPP-2M formula for the measured surface composition. Except to the electron energy of0.5 keV, a good agreement was found between the measured and predicted IMFPs in the TiN specimen.The higher discrepancies in the measured IMFPs at the lowest energy can be explained by the surfaceexcitation effect. The smallest root-mean-square-deviation and the mean percentage deviation of 2.8 Åand 14.8%, respectively, were found between EPES IMFP data and those predicted for TiN with respectto the Ni standard.

� 2012 Elsevier B.V. All rights reserved.

1. Introduction

Hot-pressed nanocrystalline titanium nitride (TiN) powder canbe fabricated into sputtering targets and used to deposit TiN thinfilms [1,2]. The TiN coatings have a broad range of applicationsin microelectronics, metal-mechanics industry and medicine. Thismaterial exhibits high hardness, excellent chemical and thermalstability, reliable mechanical performance at high temperatures[3,4]. Performance of TiN coatings is equally dependent on theirchemical composition as well as on the nature and amount ofimpurities. Thus, information on surface cleanliness and surfacechemistry may be very important for quality of the TiN layerdeposited by sputtering of hot-pressed original material.

Due to high melting temperature (2950 �C), it is difficult tomake a pressed TiN material. In the past, few papers reported itsconventional sintering at very high temperature (above 2000 �C)[5], hot isostatic pressing (HIP) [6] or hot pressing (HP) [7,8]. Nano-crystalline TiN powders offer the possibility to produce TiN bodiesat sintering temperatures of 500–600 �C lower than the powdersintering temperature for submicron and micron size particles[9,10]. As result, the nanometric TiN powders can be sintered atthe temperature range 1300–1500 �C [9]. However, the resulting

ll rights reserved.

+48 22 3433333.zyk).

powders present an extreme oxygen affinity [10,11], and a highoxygen content is always present at the surface and in the bulkas well. The physical and chemical properties of TiN are deter-mined by their surface and sub-surface region properties. There-fore, the surface sensitive electron spectroscopies, like Augerelectron spectroscopy (AES) and X-ray photoelectron spectroscopy(XPS) were often used to analyze this material [12–17].

It is well known that both electronic and ballistic processes ini-tiated by the impinging ions may stimulate significant structuraland compositional changes in the surface layer of the solids[18,19]. In general, compositional changes in the surface regionof binary compounds arise from several competing phenomena,such as preferential sputtering, radiation-enhanced diffusion,Gibbsian segregation, radiation-enhanced segregation, etc. For ni-tride compounds, these effects are not always fully recognized.Preferential sputtering phenomena were investigated in terms ofthe mass and surface binding energy effects using the Sigmund lin-ear collision cascade theory [20]. Ar-ion bombardment inducedpreferential removal of nitrogen was already detected by XPS fora number of nitrides including titanium nitride [21–24]. However,the low energy argon ion bombardment effect on surface composi-tion of the hot-pressed TiN specimens was not clarified.

The surface chemical composition of the TiN specimens can bedetermined using AES and XPS. The accurate quantification in bothtechniques requires knowledge of the electron inelastic mean free

Fig. 1. The XPS sputter depth profiles of the scraped hot-pressed TiN sample. Therelative atomic concentration depth distribution of oxygen, titanium, nitrogen andcarbon evaluated from the O 1s, Ti 2p, N 1s and C 1s XPS peaks, respectively, areshown, as a function of sputter time (Ar ion beam of 3 keV, sputter rate of 34 nm/min relative to a 100-nm-thick SiO2/Si layer). Quantification was made using theULVAC-PHI MultiPak software.

M. Krawczyk et al. / Journal of Alloys and Compounds 546 (2013) 280–285 281

path (IMFP), which is defined as the average of distances measuredalong the trajectories, that electrons with a given energy travel be-tween inelastic collisions in a substance [25,26]. Important role ofthe IMFP in the accurate quantification of AES and XPS analyses hasbeen discussed by Jablonski [27]. Much material on the IMFP datafor elements and selected inorganic and organic compounds isavailable in the literature [28]. However, no information on theIMFPs for hot-pressed TiN materials has been published. Recently,Fuentes et al. [29] have determined the IMFPs in a stoichiometricTiN film from the quantitative analysis of reflection electron en-ergy-loss spectroscopy (REELS) experiments. The determinedIMFPs for electron energies in the range of 250–2000 eV agree wellwith the values obtained from the TPP-2M formula [30]. The latterformula is implemented in the NIST Database 71 [31]. The IMFPscan be also measured experimentally by elastic-peak electronspectroscopy (EPES) [32,33]. Such measurements have been suc-cessfully performed to evaluate the IMFPs in selected binary andternary semiconductors, e.g. GaN [34], SiC [35] and InGaN [36].

In the present study, the XPS and EPES studies were carried outin order to correlate the chemical composition within the surfaceand sub-surface regions of the hot-pressed TiN sputtering targetmaterial with electron transport analysis determining the energydependence of IMFP for 0.5–2 keV electrons.

2. Experimental and theoretical methods

2.1. Samples

The hot-pressed TiN material, in the form of sputtering target disc of 50.8 mmdiameter and 6 mm thickness was purchased from Goodfellow Cambridge Ltd. Thisproduct was cut mechanically into small pieces (8 � 5 � 0.5 mm, one side mechan-ically scraped). Such samples were submitted to measurements described below.

2.2. XPS studies

Chemical composition of the hot-pressed TiN specimens within surface andsub-surface region was analyzed by XPS. High-resolution XPS measurements wereperformed using a PHI 5000 VersaProbe™ (ULVAC-PHI) spectrometer with microfo-cused and monochromatic Al Ka radiation. The spectrometer was equipped with aspherical capacitor energy analyzer with multi-channel detection within a100 � 100 lm area for XPS analysis. The X-ray beam was incident at the surfaceat the angle of 45� with respect to the surface normal. The analyzer axis was locatedat 45� with respect to the surface. For high-resolution XPS spectra, the analyzer passenergy was 23.5 eV and the energy step size was 0.1 eV. At this applied resolution,the line energy positions could be determined with an accuracy equal to or betterthan 0.2 eV.

The Casa XPS software was used to evaluate the XPS data. Deconvolution of XPSspectra were performed using a Shirley background and a Gaussian peak shape with30% Lorentzian character. Spectra of all the as-received and ion-sputtered sampleswere referenced to the C 1s line at the binding energy (BE) 285.0 eV. The atomicconcentration of titanium, nitrogen, carbon and oxygen were evaluated using theMultiline software [37], where integrated area of XPS peaks associated with theTi 2s, Ti 2p3/2, Ti 2p1/2, Ti 3s, Ti 3p, N 1s, C 1s and O 1s core levels were used for cal-culation. In addition, the XPS analysis combined with Ar+ depth profile sputtering(3 keV ions at normal angle of incidence rastered over a 2 � 2 mm2 surface area)was employed to reveal the element concentration changes inside the substrates.In this case, quantification was done using the ULVAC-PHI MultiPak software(ver. 9.0.1). The Ar+ sputter rate was 34 nm min�1, as measured using the SiO2/Sireference sample.

2.3. Measurements of probability of electron elastic-backscattering

Elastic electron backscattering probabilities from hot-pressed TiN samples weremeasured using the MICROLAB 350 spectrometer (Thermo VG Scientific) with aspherical sector analyzer. These measurements were accompanied with similarexperiments performed using two standard materials: Ni and Au. For these samplesthe values of the IMFP are known. During the measurements, the electron gun waslocated at the normal to the surface and the angle between analyzer axis and thesurface normal was 60�. The analyzer acceptance varied in the range of 1–3�. TheEPES procedure of relative measurements applied in the present work was alreadydescribed in details elsewhere [33,38]. The electron energy dependence of the IMFPfor the surface composition of the analyzed TiN samples was determined within theenergy range 0.5–2 keV. The surface excitation effects were not accounted for in thesoftware package EPES. Prior to EPES measurements, both the TiN sample and the

standard material sample were in situ sputter-cleaned by 2 keV and by 3 keV Ar+

ions, respectively, at the incidence angle of 30� with respect to surface normal. Aftersputtering, the surface contamination was entirely removed from the surface regionof metals, however, some carbon and oxygen contaminants at the nitride surfacewere still detected by AES/XPS analysis.

3. Results and discussion

3.1. XPS analysis: quantification of surface and bulk composition

Titanium, nitrogen, carbon and oxygen were detected by XPS atthe surface area of the as-prepared TiN sample. The atomic concen-tration (AC, in at.%) of Ti, N, C and O was found to be 18.3, 17, 34.3and 30.4, respectively. The resulting surface composition wasformed mainly by nearly stoichiometric titanium nitride (withthe Ti/N ratio of 1.08) and the high concentration of carbon andoxygen contaminants.

In order to remove oxygen and carbon surface contaminants,the TiN material was Ar ion etched using 3 keV Ar ion beam. Thisprocess was monitored in time by XPS measurements. In thisway, the elemental bulk distribution in-depth of analyzed materialwas monitored until the constant AC values were reached. The re-sults of the XPS depth profiling analysis are presented in Fig. 1. Therelative atomic concentration depth distribution of oxygen, tita-nium, nitrogen and carbon evaluated from the O 1s, Ti 2p, N 1sand C 1s XPS peaks, respectively, are shown as a function of sputtertime. These profiles reveal uniform chemical composition withinthe analyzed bulk TiN area. However, the oxygen and carbon con-centrations at the surface and subsurface areas exceed those ob-served inside the material, whereas the titanium and nitrogenconcentrations are distinctly lower. The final AC of Ti, N, C and Owas found to be 44.3, 35.5, 8.2 and 12 at.%, respectively. In the caseof oxygen content, its remarkable high value in the nitride is ex-pected, because titanium–oxygen interaction is thermodynami-cally proved to be easier than the titanium–nitrogen bonding.The final carbon content is more likely originated from fabricationprocedure of examined material, and should be not affected by theAr ion etching. This supposition can be supported consideringsputtering yields of titanium and carbon for the Ar ion energy usedin our experiments (3 keV). It is well known that the ratio of thesputtering yields of titanium and carbon at Ar-ion energies over

282 M. Krawczyk et al. / Journal of Alloys and Compounds 546 (2013) 280–285

1 keV approaches unity, as has been calculated by SRIM simula-tions [39]. The XPS results demonstrated clearly a preferentialsputtering of nitrogen, i.e. the sputtered surface is depleted innitrogen and enriched in Ti. This effect is visible for the studiedion energy of 3 keV at normal incidence angle.

3.2. XPS analysis: chemical state determination

Chemical states of titanium and nitrogen compounds formed onthe surface of the hot-pressed TiN sample were carefully examinedbefore and after argon sputtering. For this purpose, the high-reso-lution core level XPS spectra of Ti 2p and N 1s were analyzed.

Fig. 2 presents the results of analysis of the high-resolution Ti2p and N 1s XPS spectra recorded from the as-received TiN sample.The deconvolution of the Ti 2p spectrum (Fig. 2(a)) reveals fourmain components, and energy loss peaks (or shake-up satellites)[22,40,41]. The components 1 and 10 at the BE = 453.8 eV andBE = 459.3 eV correspond to the Ti 2p3/2 and Ti 2p1/2 spin-orbitdoublet, which can be assigned to TiC [42,43]. The spin-orbit dou-blet 2–20 with BEs of 455.0 eV (Ti 2p3/2) and 460.5 eV (Ti 2p1/2) isassociated with TiN [40,44]. The loss peaks (doublet S–S0) are lo-cated at the BE shifted for 2.4 eV to higher BE than the nitridepeaks [45,46]. The area of these peaks are fitted as 60% of the areaof the TiN peaks [40]. These peaks are due to the decrease in the

Fig. 2. The Ti 2p (a) and N 1s (b) high-resolution XPS spectra of the as-received TiNsample. Deconvoluted peaks identify various chemical compounds of titanium andnitrogen. Positions of these peaks are discussed in the text.

screening ability of the conduction electrons of Ti in TiN, and/orto energy losses, arising from interband transitions [41].

The other two peaks 3 and 30 at BE = 455.9 eV and BE = 461.3 eV,respectively, can be assigned to Ti oxynitride species TiOxNy

[44,47]. Existence of oxynitrides, i.e. Ti atoms surrounded by bothO and N atoms, was evidenced also by other authors in oxygen-containing TiNx samples [48,49]. The fourth doublet 4–40, corre-sponding to the highest BEs for the Ti 2p3/2 and Ti 2p1/2 peaks,can be attributed to TiO2 [41,48].

Deconvolution of the N 1s spectrum recorded from the as-re-ceived TiN material (Fig. 2(b)) reveals three nitrogen species. Themain nitrogen state at BE = 397.2 eV can be attributed to Ti–Nbonds in TiN [22,41]. The nitrogen contribution at BE = 396.3 eVcan be associated with Ti–N–Ti bonds in N–TiO2, resulting fromthe nitrogen substitution of oxygen in the TiO2 lattice [50,51].The nitrogen peak at BE = 398.6 eV is characteristic for N–O bondsin TiOxNy compounds [44,52].

The effect of Ar ion etching on the chemical composition of thehot-pressed TiN sample was investigated. For this purpose, theseparate sample of the same TiN material was sputtered using3 keV Ar+ beam. The Ti 2p and N 1s XPS spectra recorded fromthe TiN samples before and after sputtering are compared inFig. 3. The effect of sputtering is clearly reflected by Ti 2p and N1s line-shape changes. The same chemical components of titanium(TiC, TiN, TiOxNy, TiO2, see Fig. 2(a)) and nitrogen (N–TiO2, TiN,TiOxNy, see Fig. 2(b)) were detected for nitride samples beforeand after argon ion etching. Upon sputtering, we observed a grad-ual decrease of nitrogen, oxygen and carbon contaminant concen-trations on the surface. The preferential sputtering of nitrogenfrom the nitride or oxynitride compounds evidently affect theTiN surface composition. It should be also underlined that oxygenwas still detected after 3 keV Ar ion sputtering.

Most of carbon contaminants, mainly aliphatic and carbonylspecies, were removed from the surface as result of argon ion etch-ing. However, it is well known that the argon ion interaction withcarbon species can induce a titanium carbide formation [53]. Wealso detected the TiC on the sputtered TiN samples. Its presencewas revealed in the Ti 2p (see Fig. 2(a)) and C 1s spectra (notshown here) as well. On the TiN samples sputtered by 3 keV Arions, the TiC contribution determined from the C 1s XPS spectrum(at BE = 282.3 eV [54]) attains 45% of the total population of carboncompounds detected on the surface.

3.3. EPES analysis: determination of the energy dependence of IMFP

To find experimentally the IMFP, characterizing electron trans-port in the studied TiN material within the energy range 0.5–2 keV,the relative EPES measurements were performed for both the Niand Au standards. Prior to EPES measurements, the TiN samplewas sputter-cleaned using 2 keV Ar+ ions etching for 5 min. Thisprocedure resulted in Ti0.39N0.31O0.13C0.17 surface composition, asdetermined by XPS.

Fig. 4 presents a comparison of the measured IMFPs (uncor-rected for surface excitation effects) and the values predicted fromthe TPP-2M formula [30] for the presently measured surface com-position. Except the electron energy E of 0.5 keV, good agreementbetween measured and predicted electron IMFPs in TiN was found.For all of the examined energies, except the energy of 1 keV, theIMFPs measured using the Ni standard are always slightly largerthan values measured using the Au standard. The difference atE = 0.5 keV may be due to the surface inelastic electron excitations.

Generally, the EPES method requires the correction of the sur-face excitation effect to determine the absolute values of the IMFPsor when the measurements were made without a standard [28].Since the IMFPs are determined in EPES measurements from theratios of elastically backscattered intensities for the sample and

Fig. 3. Line-shape evolution of the Ti 2p (a) and N 1s (b) high-resolution XPS spectrarecorded from TiN samples due to sputtering: (1) the as-received sample; (2) thesputtered sample (E = 3 keV). Both spectra are normalized to a common height ofthe most intense peaks.

Fig. 4. Measured and predicted IMFPs for TiN, as a function of electron energy.Circles: the EPES IMFPs obtained for the hot-pressed TiN material with respect tothe Ni standard. Triangles: the EPES IMFPs obtained for the hot-pressed TiNmaterial with respect to the Au standard. Solid line: TPP-2M predictive formula[30]. For comparison, we include IMFPs published by Fuentes et al. [29] (solidcircles) for TiN.

M. Krawczyk et al. / Journal of Alloys and Compounds 546 (2013) 280–285 283

the standard, the ratios of corrections to bulk IMFPs (to take ac-count of surface excitations) for the two materials are likely tobe close to unity. For the presently used both Ni and Au standards,we have calculated the f TiN

s =f Nis and f TiN

s =f Aus ratios, i.e. the surface

electronic excitation (SEE) corrections [33], using values of thematerial parameters ‘a’ [55] and the surface excitation probabili-ties (SEP), Ps(a, E), determined from the simple expression of Os-wald [56] and later modified by Werner et al. [55,57]. Thesecalculations were performed for both the incident and the escapingelectrons under the experimental configurations used. The ‘a’ val-ues for TiN, Ni and Au were found to be 1.10, 1.78 and 1.57, respec-tively. Moreover, it was found that both values of f TiN

s =f Nis and

f TiNs =f Au

s increased from about 0.85 and 0.88, respectively, at500 eV to about 0.90 and 0.92, respectively, at 2000 eV. Therefore,we can still correct the present EPES IMFPs for the surface excita-tion effects, especially at the lowest energy E = 500 eV.

For comparison, Fig. 4 shows the already published energydependence of IMFP (solid circles) in TiN [29]. On close inspectionof this figure, we notice that the presently measured IMFPs forelectron energies E > 500 eV agree well with those determined byFuentes et al. [29] from the quantitative analysis of REELSmeasurements.

The TPP-2M predictive formula for the IMFP, k, is given by themodified Bethe equation [30]

k ¼ E

E2p½b lnðcEÞ � ðC=EÞ þ ðD=E2Þ�

ð1Þ

where E is the electron energy (in eV), and

Ep ¼ 28:8

ffiffiffiffiffiffiffiffiffiNvqM

rð1aÞ

b ¼ �0:10þ 0:944ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiE2

p þ E2g

q þ 0:069q0:1 ð1bÞ

c ¼ 0:191q�0:5 ð1cÞC ¼ 1:97� 0:91U ð1dÞD ¼ 53:4� 20:8U ð1eÞ

U ¼ NvqM¼

E2p

829:4ð1fÞ

Thus, the IMFP is a function of the electron energy and proper-ties of the sample: the density q (in g cm�3), the number of valenceelectrons Nv per atom or molecule, the atomic or molecular weightM, and the band-gap energy Eg (in eV). In Eq. (1a), the free-electronplasmon energy Ep (in eV) can be calculated using the parametersq, Nv and M. Values of the four other parameters b, c, C and D in Eq.(1) are calculated from Eqs. (1b), (1c), (1d), (1e). For titanium ni-tride, values of Eg, Ep, and q are 3.4 eV, 16.8 eV and 5.22 g cm�3

[58], respectively. The latter value is much smaller than the corre-sponding value of pure bulk TiN without a previous hot pressing

284 M. Krawczyk et al. / Journal of Alloys and Compounds 546 (2013) 280–285

treatment [59]. For TiN, Nv = 4 is calculated from the sum of contri-butions from each constituent element (i.e., Nv for each elementmultiplied by the stoichiometric coefficient for that element) [31].

To compare numerically the EPES-determined IMFPs withoutcorrections for surface excitations with the corresponding pre-dicted IMFPs, a statistical analysis of the data was made usingthe root-mean-square deviation (RMS) and the mean percentagedeviation (R). These parameters were calculated from

RMS ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi1r

Xr

n¼1

ðkn � ktheoryÞ2s

R ¼ 1001r

Xr

n¼1

kn � ktheory

ktheory

�������� ð2Þ

where r is the total number of experimental inelastic mean freepath values kn uncorrected for surface excitations (in the presentwork, calculations were made for a number of IMFPs, r = 4) andktheory denotes the IMFP value calculated from the TPP-2M equa-tion [30] at a particular electron energy. The RMS and R deviationsresulting from Eq. (2) of 2.8 Å and 14.8%, respectively, were foundbetween EPES IMFP data (Ni standard) and those predicted usingthe TPP-2M (Eq. (1)) for TiN. These values related to the Au stan-dard were 5 Å and 24.3%, respectively. The observed deviationsfor both Ni and Au standards were small but relatively larger forthe Au standard. Both values indicated adequate or high consis-tency between measured and predicted IMFPs for the TiN sample.However, it should be noted that EPES measurements were af-fected by the surface effects which were presently neglected.

4. Conclusions

In the present study, variation of chemical composition of bothsurface and sub-surface region of hot-pressed TiN material wascorrelated with electron transport analysis, which provided thereliable IMFPs. XPS analysis of the as-received samples revealedhigh-concentration of oxygen and carbon contaminants, whichwere impossible to remove entirely using argon ion sputtering, inaddition to the main TiN component. The presence of titanium ni-tride, titanium dioxide, and a mixed titanium oxynitride com-pounds, which are usually formed at the first stage of TiNoxidation, were identified. The examined samples of TiN sputteringtargets were found to have insufficient purity, resulting from oxi-dation during storage in air, and also sintering and purifying treat-ments in various gas atmospheres.

The bombardment of TiN specimens by argon ions leads to sur-face composition change as result of preferential sputtering ofnitrogen. The bombarded surfaces were enriched in Ti after 3 keVargon ion etching. XPS depth profiles studies indicated the uniformdistribution of titanium and nitrogen in the bulk of hot-pressedmaterial.

EPES applied without corrections for surface excitations andbased on both Ni and Au standards proved to be a useful methodfor experimental determination of the energy dependence of IMFPsin hot-pressed TiN samples. Except to the electron energy of0.5 keV, good agreement between measured and predicted elec-tron IMFPs in TiN was found. Values of RMS and R, describingthe scatter, indicated adequate consistency between measuredand predicted IMFPs.

Acknowledgement

This work has been financed by the NCN Project DEC-2011/01/B/ST4/00959.

References

[1] S. Xu, L. Du, K. Sugioka, K. Toyoda, M. Jyumonji, J. Mater. Sci. (1998) 1777–1782.

[2] K. Wasa, M. Kitabatake, H. Adachi, Thin Film Materials Technology: Sputteringof Compound Materials, William Andrew, Inc.,-Springer-Verlag GmbH&Co. KG,Norwich-Heidelberg, 2004.

[3] R.G. Munro, J. Res. Natl. Inst. Stand. Technol. 105 (2000) 709–720.[4] J.E. Sundgren, Thin Solid Films 128 (1985) 21–44.[5] M.A. Kuzenkova, P.S. Kislyi, Metal 98 (1971) 125–128.[6] L. Themelin, M. Desmaison-Brut, M. Boncoeur, F. Valin, L’Industrie Céramique

828 (1988) 426–433.[7] T. Yamada, M. Shimada, M. Koizumi, Am. Ceram. Soc. Bull. 59 (1980) 611–616.[8] E. Rapoport, C. Brodhag, F. Thévenot, Rev. de Chim. Minérale 22 (1985) 456–

466.[9] R.A. Andrievski, Nanostruct. Mater. 9 (1997) 607–610.

[10] O.B. Zgalat-Lozinskii et al., Powder Metall. Met. Ceram. 40 (2001) 471–477.[11] J.R. Groza, J.D. Curtis, M. Kramer, J. Am. Ceram. Soc. 83 (2000) 1281–1283.[12] W. Palmer, Surf. Interface Anal. 13 (1988) 55–60.[13] K. Hinode, Y. Homma, M. Horiuchi, T. Takahashi, J. Vac. Sci. Technol. A 15

(1997) 2017–2022.[14] G. Gonzalez-Valenzuela, L. Cota, R. Gonzalez- Valenzuela, W. de la Cruz, A.

Duarte-Moller, Appl. Surf. Sci. 252 (2006) 3401–3405.[15] I. Bertóti, Surf. Coat. Technol. 151-152 (2002) 194–203.[16] J.F. Marco, J.R. Gancedo, M.A. Auger, O. Sanchez, J.M. Albella, Surf. Interface

Anal. 37 (2005) 1082–1091.[17] A. Glaser, S. Surnev, F.P. Netzer, N. Fateh, G.A. Fontalvo, C. Mitterer, Surf. Sci.

601 (2007) 1153–1159.[18] I. Bertóti, A. Tóth, M. Menyhard, in: J.C. Rivière, S. Myhra (Eds.), Handbook of

Surface and Interface Analysis, Marcel Dekker Inc., New York, 1998, p. 297.[19] R. Kelly, I. Bertóti, A. Miotello, Nucl. Instrum. Methods B 80-81 (1993) 1154–

1163.[20] P. Sigmund, in: R. Behrisch (Ed.), Sputtering by Particle Bombardment I,

Springer-Verlag, Berlin, 1981, p. 9 (Chapter 2).[21] L. Kubler, R. Haug, E.K. Hlil, D. Bolmont, G. Gewinner, J. Vac. Sci. Technol. A 4

(1986) 2323–2327.[22] I. Bertóti, M. Mohai, J.L. Sullivan, S.O. Saied, Surf. Interface Anal. 21 (1994) 467–

473.[23] P. Ettmayer, W. Lengauer, Nitrides, Ullmann’s Encyclopedia of Industrial

Chemistry, Wiley-VCH Verlag GmbH & Co.k, GaA, 2000.[24] J. Kovac, A. Zalar, Surf. Interface Anal. 34 (2002) 253–256.[25] Surface chemical analysis – vocabulary, ISO 18115, International Organisation

for Standardisation, Geneva, 2001.[26] Standard Terminology Relating to Surface Analysis, ASTM E673-03, Annual

Book of ASTM Standards, 2006, vol. 3.06, ASTM International, WestConshohocken, 2006, p.647.

[27] A. Jablonski, Surf. Sci. 603 (2009) 1342–1352.[28] C.J. Powell, A. Jablonski, J. Phys. Chem. Ref. Data 28 (1999) 19–62.[29] G.G. Fuentes, E. Elizalde, F. Yubero, J.M. Sanz, Surf. Interface Anal. 33 (2002)

230–237.[30] S. Tanuma, C.J. Powell, D.R. Penn, Surf. Interface Anal. 21 (1994) 165–176.[31] C.J. Powell, A. Jablonski, NIST ELECTRON INELASTIC-MEAN-FREE-PATH

DATABASE, Version 1.1, Standard Reference Data Program Database 71, US.Department of Commerce, National Institute of Standards and Technology,Gaithersburg, MD, 2000 (<http://www.nist.gov/srd/nist71.htm>).

[32] G. Gergely, Surf. Interface Anal. 3 (1981) 201–205.[33] A. Jablonski, Surf. Interface Anal. 37 (2005) 1035–1044.[34] M. Krawczyk, L. Zommer, A. Jablonski, I. Grzegory, M. Bockowski, Surf. Sci. 566-

568 (2004) 1234–1239.[35] M. Krawczyk, L. Zommer, A. Kosinski, J.W. Sobczak, A. Jablonski, Surf. Interface

Anal. 38 (2006) 644–647.[36] M. Krawczyk, W. Lisowski, J.W. Sobczak, A. Kosinski, A. Jablonski, C.

Skierbiszewski, M. Siekacz, S. Wiazkowska, J. Alloys Comp. 509 (2011) 9565–9571.

[37] A. Jablonski, Anal. Sci. 26 (2010) 155–164.[38] M. Krawczyk, A. Kosinski, A. Jablonski, A. Mycielski, Surf. Sci. 600 (2006) 3744–

3748.[39] W. Eckstein, J.P. Biersack, Appl. Phys. A37 (1985) 95–108.[40] I. Milosev, H.-H. Strehblow, B. Navinsek, M. Metikos-Hukovic, Surf. Interface

Anal. 23 (1995) 529–539.[41] I. Strydom, S. Hofmann, J. Electron Spectrosc. Relat. Phenom. 56 (1991) 85–

103.[42] P.Y. Jouan, M.C. Peignon, C.H. Cardinaud, G. Lemperiere, Appl. Surf. Sci. 68

(1993) 595–603.[43] R. Bertoncello, A. Casagrande, M. Casarin, A. Glisenti, E. Lanzoni, L. Mirenghi, E.

Tondello, Surf. Interface Anal. 18 (1992) 525–531.[44] Y.L. Jeyachandran, S. Venkatachalam, B. Karunagaran, Sa.K. Narayandass, D.

Manglaraj, C.Y. Bao, C.L. Zhang, Mater. Sci. Eng. C 27 (2007) 35–41.[45] K. Tanaka, H. Yanashima, T. Yako, K. Kamio, K. Sugai, S. Kishida, Appl. Surf. Sci.

171 (2001) 71–81.[46] J. Guillot, F. Fabreguette, L. Imhoff, O. Heintz, M.C. Marco de Lucas, M. Sacilotti,

B. Domenichini, S. Bourgeois, Appl. Surf. Sci. 177 (2001) 268–272.[47] F. Esaka, K. Furuya, H. Shimada, M. Imamura, N. Matsubayashi, H. Sato, A.

Nishijima, A. Kawana, H. Ichimura, T. Kikuchi, J. Vac. Sci. Technol. A 15 (1997)2521–2528.

M. Krawczyk et al. / Journal of Alloys and Compounds 546 (2013) 280–285 285

[48] K.S. Robinson, B.M.A. Sherwood, Surf. Interface Anal. 6 (1984) 261–266.[49] N. Kaufherr, D. Lichtman, J. Vac. Sci. Technol. A 3 (1989) 1969–1972.[50] M.-S. Wong, H.P. Chou, T.-S. Yang, Thin Solid Films 494 (2006) 244–249.[51] F. Peng, L. Cai, H. Yu, H. Wang, J. Yang, J. Solid State Chem. 181 (2008) 130–136.[52] P.-Y. Jouan, M.-C. Peignon, Ch. Cardinaud, G. Lemperiere, Appl. Surf. Sci. 68

(1993) 595–603.[53] G.M. Ingo, S. Kaciulis, A. Mezzi, T. Valente, G. Gusmano, Surf. Interface Anal. 36

(2004) 1147–1150.[54] G. Radhakrishnan, P.M. Adams, D.M. Speckman, Thin Solid Films 358 (2000)

131–138.[55] W.S.M. Werner, W. Smekal, C. Tomastik, H. Störi, Surf. Sci. 486 (2001) L461–

L466.

[56] R. Oswald, Numerische untersuchung der elastischen streuung von elektronenan atomen und ihrer rückstreuung an oberflächen amorpher substanzen imenergiebereich unter 2000 eV, Ph.D. Thesis, Eberhard-Karls-Universität,Tübingen, 1992.

[57] W.S.M. Werner, Surf. Interface Anal. 31 (2001) 141–176.[58] Goodfellow on-line catalogue 2011 (<http://www.goodfellow.com/

catalogue>).[59] J. Russias, S. Cardinal, J. Fontaine, G. Fantozzi, C. Esnouf, K. Bienvenu, Int. J.

Refract. Met. Hard Mater. 23 (2005) 344–349.