Zr thin films were deposited by DC magnetron sputtering technique on Si substrate and then post-annealed at different temperatures (150-750 °C in steps of 150 °C) and times (60 and 180 min) with flow of oxygen. X-ray diffraction (XRD) method was used for study of crystallographic structure. These results showed an orthorhombic structure for annealed films at 150 and a mixed structure of monoclinic and tetragonal for annealed films at higher temperatures (300-750 ºC). XRD result also showed that an increase in annealing temperature and time caused increasing of crystalline size. EDAX and AFM tech-niques were employed for investigation of chemical composition and surface morphology of samples, re-spectively. The results showed a granular structure for all samples, while the O / Zr ratio, grains size and surface roughness were increased with increasing of annealing temperature and time. A two probe instru-ment was used for electrical properties investigation, while hardness of films was measured by nano-indentation test. These results showed that increasing of annealing temperature and time caused increas-ing of electrical resistance and decreasing of hardness in the films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3513

Borzou, A.

Jafari, F.

Khojier, K.

Sarshar, S.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 1, 01NTF06(4pp) (2013)   2304-1862/2013/2(1)01NTF06(4) 01NTF06-1  2013 Sumy State University Nano-structural, Electrical and Mechanical Characterization of Zirconium Oxide Thin Films as a Function of Annealing Temperature and Time  K. Khojier1,*, S. Sarshar2,†, F. Jafari2,‡, A. Borzou1,§  1 Department of physics, Chalous branch, Islamic Azad University, Chalous, Iran 2 Department of physics, Faculty of sciences, Central Tehran branch, Islamic Azad University, Tehran, Iran  (Received 07 May 2013; published online 30 August 2013)  Zr thin films were deposited by DC magnetron sputtering technique on Si substrate and then post-annealed at different temperatures (150-750 °C in steps of 150 °C) and times (60 and 180 min) with flow of oxygen. X-ray diffraction (XRD) method was used for study of crystallographic structure. These results showed an orthorhombic structure for annealed films at 150 and a mixed structure of monoclinic and tetragonal for annealed films at higher temperatures (300-750 ºC). XRD result also showed that an  increase in annealing temperature and time caused increasing of crystalline size. EDAX and AFM tech-niques were employed for investigation of chemical composition and surface morphology of samples, re-spectively. The results showed a granular structure for all samples, while the O / Zr ratio, grains size and surface roughness were increased with increasing of annealing temperature and time. A two probe instru-ment was used for electrical properties investigation, while hardness of films was measured by nano-indentation test. These results showed that increasing of annealing temperature and time caused increas-ing of electrical resistance and decreasing of hardness in the films.  Keywords: Zirconium oxide, Thin film, Post-annealing, Nano-structure, Hardness, Electrical resistance.   PACS numbers: 64.46.Hk, 61.05.Cp, 62.20.Qp, 73.61.At                                                           * khojier@iauc.ac.ir † soheilasarshar@yahoo.com ‡ Asalj1364@gmail.com § farshadbr@yahoo.com 1. INTRODUCTION  Physical properties of nano-materials have been a subject of intense scrutiny over the past two decades because of the scientific and technological interest on the preparation method and nanostructure dependence of these properties [1-4]. Zirconia (ZrO2) is one of these materials that especially in the thin film form is very attractive. ZrO2 has been applied at thermal barrier coatings [5], optical filters and laser mirrors [6], alter-native gate dielectrics in microelectronics [7, 8], a buff-er layer for a high Tc ceramic superconductor on Si [9], high temperature oxygen separation [10], oxygen sen-sors [11] and fuel cells [12] due to its heat resistance, low thermal conductivity, a relative high dielectric con-stant, high refractive index, high transparency in the visible and near-infrared region [13, 14]. In all these practical applications, the preparation method, control of growth, crystal structure, chemical composition, and electronic properties of ZrO2 thin films are very im-portant. Hence, characterization of structural, electrical, mechanical and optical properties of Zirconia thin films prepared using different deposition techniques and cor-relation between nano-structure and different properties of these films play an important role in their technical applications. Many researchers have been reported on investigation of different properties of ZrO2 thin films prepared by different methods including thermal anneal-ing [15, 16], sputtering [17, 18], reactive sputtering [19, 20], Chemical Vapor Deposition [21], electron beam evaporation [22], and sol-gel processing [23]. In this work, in order to more deeply understand the effect of annealing conditions on the Zr thin films, we have prepared the Zirconium oxide thin films by post-annealing of Zr / Si films at different temperatures and times, and studied the influence of these variables on crystallographic structure, surface morphology, chemical composition and electrical and mechanical properties of these layers.  2. EXPRIMENTAL DETAIL  Conventionally polished silicon (Si (400), n-type) with dimensions of 20  20 mm2 were used as a sub-strate. The substrates were cleaned with acetone and ethanol in ultrasound cleaner for several minutes and were dried by argon gas flow. Zr thin films of 90 nm thickness were deposited by means of DC magnetron sputtering system using a circular sputtering target (99.998 % purity) of 76 mm diameter and 1 mm thick-ness. The target to substrate distance was 10 cm. A continuously variable DC power supply of 600 V and 150 mA was used as a power source for sputtering. The thickness and deposition rate of the Zr films were checked in situ using a quartz crystal monitor (6 MHz gold, Inficon Company, USA) located near the sub-strate during the sputtering process. Zirconium thin films were deposited at a deposition rate of 9 Å/s. The base pressure was 4  10 – 5 mbar, achieved with a diffusion pump coupled with a rotary pump that was changed to 2.8  10 – 3 mbar after presence of Argon. The purity of argon gas in this work was 99.998 % and controlled by mass flow controller. Post-annealing of Zr / Si films were performed by a tube furnace at five  K. KHOJIER, S. SARSHAR, F. JAFARI, A. BORZOU PROC. NAP 2, 01NTF06 (2013)   01NTF06-2 different temperatures (150 to 750 C in steps of 150 C) with flow of oxygen (purity of 99.98 %) at 200 sccm (standard cubic centimeter per minute). Two annealing times of 60 and 180 min were used. The samples were reached the selected annealing temper-ature with a thermal gradient of 5 degree/min, and then gradually cooled down to room temperature. The details of the samples produced in this work are given in Table 1. Nanostructure and crystallographic orien-tation of the samples were obtained using a Philips XRD X’pert MPD Diffractometer (Cu Kα radiation, 40 kV and 30 mA) with a step size of 0.02° and count time of 1 s per step. A Field Emission Scanning Elec-tron Microscope FESEM (model: CamScan MV2300, Czech & England) and an Atomic Force Microscope (Auto probe PC, Park Scientific Instrument, USA) were also employed for investigation of chemical com-position and surface morphology, respectively. The electrical resistance of films was also measured by two probe instrument with an excitation wavelength at 320 nm, while films hardness was measured by nano-indentation test.  3. RESULT AND DISCOSION  Fig. 1 shows X-ray diffraction patterns of Zr / Si thin films annealed at different temperature for 60 min. XRD pattern of annealed sample at 150 Cshows two peaks at 31.91 and 34.25 can be related to ZrO2 (012) and ZrO2 (111) diffraction lines of orthorhombic phase (with reference to JCPDS Card No.: 33-1483, and 2: 31.889 and 34.222). By in-creasing of annealing temperature to 300 C, men-tioned peaks of orthorhombic phase are omitted and three new peaks are observed at 28.05, 29.81, and 34.23. These peaks can be attributed to ZrO2 (111) crystallographic orientation of monoclinic phase (with reference to JCPDS Card No.: 05-0543, and 2: 28.036), ZrO2 (101) crystallographic orientation of tetragonal phase (with reference to JCPDS Card No.: 24-1164, and 2: 29.807), and ZrO2 (002) crystallo-graphic orientation of monoclinic phase (with refer-ence to JCPDS Card No.: 05-0543, and 2: 34.195), respectively. With increasing of annealing tempera-ture to the higher temperatures (450, 600 and 750 C) don’t observe any new peaks. On the other hand, it can be concluded that the annealing temperature (in the range of 300-750 C) have little influence on the structure of ZrO2 films. The above mentioned behavior was also observed for annealed samples at higher an-nealing time (i.e., samples S6-S10). The XRD results detail of all samples are given in Table 1. It can be seen in column 4 of Table 1, that the position of all diffraction lines are shifted to higher diffraction an-gles relative to that of powder sample with increasing the annealing temperature. In addition those samples annealed at higher time (i.e. 180 min) show larger shift than those annealed at 60 min. These behaviors can be related to increasing of tensile stress by in-creasing of annealing temperature and time. The ten-sile stress can be also attributed to higher thermal expansion coefficient of ZrO2 to Si that increases at higher annealing temperatures and time. In order to obtain the crystalline size (coherently diffracting domains) of the samples we used the Scher-rer relation [24]:   coskDB    where,  is the wavelength of X-ray,  is the Bragg angle, and k is a dimensionless constant which is re-lated to the shape and distribution of crystallites [25] (usually taken as unity). For obtaining the value for, we used the usual procedure of full width at half max-imum (FWHM) measurement technique [26], there-fore:    12 2 20 iB W W     where, W0 is the FWHM of the sample and Wi is the FWHM of stress free sample (standard SiO2 single crystal sample). The calculated crystalline size, D ob-tained from the above procedure is given in column 5 of Table 1. This result shows that the increasing of an-nealing temperature and time cause the increasing of crystalline size in these films. This behavior may be due to high annealing temperature / more annealing time that provides energy of film atoms to enhance mo-bility. Increasing of mobility can also increases the coa-lescence and decreases the defects and cause the im-provement of pores and quality of ZrO2 films.    Fig. 1 – XRD patterns of Zr / Si thin films annealed at differ-ent temperatures for 60 min  3D AFM images of selected samples (annealed at different temperatures for 60 min) are shown in Fig. 2. The grains size (calculated by JMicrovision code from 2D AFM images) and surface roughness of all samples are plotted in Fig. 3 and 4, respectively. These results show that an increase in annealing temperature and time caused increasing grains size (consistent with XRD results) and surface roughness. Increasing of sur-face roughness can be related the increasing of grains size as mentioned before.    NANO-STRUCTURAL, ELECTRICAL AND MECHANICAL CHARACTERIZATION… PROC. NAP 2, 01NTF06 (2013)   01NTF06-3 Table 1 – Detail of XRD analysis   T,(C) T,(min) 2 (deg.), (hkl) D, (nm) S1 150 60 31.89 / 34.23 O(012) / O(112) 33 / 37 S2 300 60 28.05 / 29.81 / 34.21 M(111) / T(101) / M(002) 61 / 65 / 64 S3 450 60 28.07 / 29.83 / 34.23 M(111) / T(101) / M(002) 83 / 81 / 87 S4 600 60 28.07 / 29.83 / 34.25 M(111) / T(101) / M(002) 97 / 95 / 102 S5 750 60 28.09 / 29.85 / 34.27 M(111) / T(101) / M(002) 133 / 159 /  151 S6 150 180 39.91 / 34.25 O(012) / O(112) 42 / 46 S7 300 180 28.07 / 29.83 / 34.21 M(111) / T(101) / M(002) 64 / 68 / 71 S8 450 180 28.09 / 29.85 / 34.23 M(111) / T(101) / M(002) 89 / 88 / 93 S9 600 180 28.09 / 29.87 / 34.27 M(111) / T(101) / M(002) 107 / 110 /  115 S10 750 180 28.09 / 29.87 / 34.29 M(111) / T(101) / M(002) 147 / 162 /  157    Fig. 2 – AFM images of Zr / Si thin films annealed at different temperatures for 60 min  The chemical composition of films was investigated by EDAX analysis. The results obtained from this anal-ysis are shown in Fig. 5. These results show that ratio of O / Zr increases with increasing of annealing tem-perature and time. On the other hand, increasing of annealing temperature in the range of 150-750 C, and annealing time improve the oxidation process. Variation of electrical resistance of Zirconium oxide thin films obtained from two probe instrument for selected samples (annealed for 60 min) is shown in Fig. 6. The re-sult shows that an increase in annealing temperature results increasing of films electrical resistance. It can be due to the increasing of oxygen vacancies in films body with increasing of annealing temperature. Detail of hardness values of films is shown in Fig. 7. It can be seen that films hardness decreases with in-creasing of annealing temperature and time. This re-duction can be related to increasing of crystalline size and surface roughness with annealing temperature and time (according to XRD and AFM results).    Fig. 3 – Variation of grain size of zirconium oxide thin films prepared at different times as a function of annealing temper-ature    Fig. 4 – Variation of surface roughness of zirconium oxide thin films prepared at different times as a function of annealing temperature    Fig. 5 – The ratio of O / Zr in zirconium oxide thin films pre-pared at different times as a function of annealing tempera-ture  1101001000100001000001000000100000000.001 0.01 0.1 1 10V (V)I (nA)150 °C300 °C450 °C600 °C700 °C  Fig. 5 – Variation of current as a function of voltage of Zr / Si thin films annealed at different temperature and time  In a polycrystalline film, grain size has a tremen-dous influence on the mechanical properties. Because grains usually have various crystallographic orienta-tions, grain boundaries arise, while an undergoing de-formation, slip motion will take place. Grain bounda-ries act as an impediment to dislocation motion for the  K. KHOJIER, S. SARSHAR, F. JAFARI, A. BORZOU PROC. NAP 2, 01NTF06 (2013)   01NTF06-4 following two reasons: (1) dislocation must change its direction of motion due to the different orientations of grains; (2) discontinuity of slip planes from one grain to another [27]. It is also reported that film hardness and surface roughness have an inverse relation [28], so that the films with more surface roughness may possibly have an open and porous structure, which leads to low-er hardness.    Fig. 6 – Variation of hardness of zirconium oxide thin films prepared at different times as a function of annealing temper-ature  4. CONCLUSION  Zirconium Oxide thin films prepared by post-annealing of Zr / Si (400) thin films (with 90 nm thick-ness) at different annealing temperatures (150-750 C) and  different annealing times (60 and 180 min) were studied. Nanostructure and surface morphology of these layers were considered by XRD, AFM techniques, when the chemical composition of the films were inves-tigated by EDAX analysis. The electrical resistance and films hardness were measured by a two probe instru-ment and nano-indentation test. The results showed:  I) The films annealed at 150 C were a polycrystal of orthorhombic phase, while samples annealed at higher temperatures (300 -750 C) showed a mixed structure of monoclinic and tetragonal.  II) Increasing of annealing temperature and time caused increasing of crystalline size, surface roughness, ratio of O / Zr in the films. III) An increase in annealing temperature and time caused increasing of electrical resistance that was re-lated to increasing of oxygen vacancies in films struc-ture. IV) The hardness of zirconium oxide thin films de-creased with increasing of annealing temperature and time that were due to the increasing of grains size and surface roughness with these variables.  AKNOWLGMENT  This work was carried out with the support of the Islamic Azad University, Chalous branch and Central Tehran Branch. The authors are grateful to Prof. H. Savaloni. REFERENCES  1. A.N. Banerjee, K.K. Chattopadhyay, J. Appl. Phys. 97, 084308 (2005). 2. A.V. Morozovska, E.A. Eliseev, Phys. Rev. B 73, 104440 (2006). 3. D. Katz, T. Wizansky, O. Millo, E. Rothenberg, T. Mokari, U. Banin, Phys. Rev. Lett. 89, 086801 (2002). 4. K. Khojier, H. Savaloni, Vacuum 84, 770 (2010). 5. S.M. Meier, D.K. Gupta, J. Eng. Gas Turbines Power Trans. ASME 116, (1994) 250. 6. W.H. Lowdermilk, D. Milam, F. Rainer, Thin Solid Films 73, 155 (1980). 7. M. Copel, M. Gribelyyuk, E. Gusev, Appl. Phys. Lett. 76, 436 (2000). 8. M. Houssa, V.V. Afanas’ev, A. Stesmans, M.M. Heyns, Appl. Phys. Lett. 77, 1885 (2000). 9. D.K. Fork, D.B. Fenner, G.A.N. Connell, J.M. Phillips, T.H. Geballe, Appl. Phys. Lett. 57, 1137 (1990). 10. J. Han, Y. Zeng, G. Xomeritakis, Y.S. Lin, Solid State Ion-ics 98, 63 (1997). 11. M. Sayer, K. Sreenivas, Science 247, 1056 (1990). 12. N.Q. Minh, J. Am. Ceram. Soc.76, 563 (1993). 13. P. Baumeister, O. Arnon, Appl. Opt. 16, 439 (1977). 14. M.A. Russak, C.V. Jahnes, E.P. Katz, J. Vac. Sci. Technol. A 7, 1248 (1989). 15. P.Y. Kuei, J.D. Chou, C.T. Huang, H.H. Ko, S.C. Su,  J. Cryst. Growth 314, 81 (2011). 16. J. Ciosek, W. Paszkowicz, P. Pankowski, J. Firak, U. Stanislawek, Z. Patron, Vacuum 72, 135 (2004).   17. A.P. Huang, P.K. Chu, Mat. Sci. Eng. 121, 244 (2005). 18. L.F. Cueto, E. Sanchez, L.M. Torres-Martinez, G.A. Hirata, Mater Charact. 55, 263 (2005). 19. B.J. Lee, H.L. Sohn, Y.T. Cho, J. Korean Phys. Soc. 51, 1038 (2007). 20. L.D. Huy, P. Laffez, P. Daniel, A. Jouanneaux, N.T. Khoi, D. Simeone, Mat. Sci. Eng. B: Solid. 104, 163 (2003). 21. J.J. Yu, I.W. Boyd, Appl. Surf. Sci. 208-209, 374 (2003). 22. Y.M. Shen, S.Y. Shao, H. Yu, Z.X. Fan, H.B. He, J.D. Sha, Appl. Surf. Sci. 254, 552 (2007). 23. W.C. Liu, D. Wu, A.D. Li, H.Q. Ling, Y.F. Tang, N.B. Ming, Appl. Surf. Sci. 191, 181 (2002). 24. B.E. Warren, X-ray Diffraction (Addison Wesley Publish-ing Co.: London: 1969). 25. J.I. Langford, A.J. Wilson, J. Appl. Cryst. 11, 102 (1978).  26. T.C. Huang, G. Lim, F. Parmigiani, E. Kay, J. Vac. Sci. Technol. A 3, 2161 (1985). 27. T.G. Wang, D. Jeong, Y. Liu, Q. Wang, S. Iyengar, S. Melin, K.H. Kim, Surf. Coat. Technol. 206, 2638 (2012). 28. K. Koski, J. Holsa, P. Juliet, Surf. Coat. Technol. 120-121, 303 (1999).  

Nano-structural, Electrical and Mechanical Characterization of Zirconium Oxide Thin Films as a Function of Annealing Temperature and Time

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 1, 01NTF06(4pp) (2013) 
 
 
2304-1862/2013/2(1)01NTF06(4) 01NTF06-1  2013 Sumy State University 
Nano-structural, Electrical and Mechanical Characterization of Zirconium Oxide Thin Films 
as a Function of Annealing Temperature and Time 
 
K. Khojier1,*, S. Sarshar2,†, F. Jafari2,‡, A. Borzou1,§ 
 
1 Department of physics, Chalous branch, Islamic Azad University, Chalous, Iran 
2 Department of physics, Faculty of sciences, Central Tehran branch, Islamic Azad University, Tehran, Iran 
 
(Received 07 May 2013; published online 30 August 2013) 
 
Zr thin films were deposited by DC magnetron sputtering technique on Si substrate and then post-
annealed at different temperatures (150-750 °C in steps of 150 °C) and times (60 and 180 min) with flow of 
oxygen. X-ray diffraction (XRD) method was used for study of crystallographic structure. These results 
showed an orthorhombic structure for annealed films at 150 and a mixed structure of monoclinic and 
tetragonal for annealed films at higher temperatures (300-750 ºC). XRD result also showed that an  
increase in annealing temperature and time caused increasing of crystalline size. EDAX and AFM tech-
niques were employed for investigation of chemical composition and surface morphology of samples, re-
spectively. The results showed a granular structure for all samples, while the O / Zr ratio, grains size and 
surface roughness were increased with increasing of annealing temperature and time. A two probe instru-
ment was used for electrical properties investigation, while hardness of films was measured by nano-
indentation test. These results showed that increasing of annealing temperature and time caused increas-
ing of electrical resistance and decreasing of hardness in the films. 
 
Keywords: Zirconium oxide, Thin film, Post-annealing, Nano-structure, Hardness, Electrical resistance. 
 
 PACS numbers: 64.46.Hk, 61.05.Cp, 62.20.Qp, 73.61.At 
 
 
                                                        
* khojier@iauc.ac.ir 
† soheilasarshar@yahoo.com 
‡
 Asalj1364@gmail.com 
§ farshadbr@yahoo.com 
1. INTRODUCTION 
 
Physical properties of nano-materials have been a 
subject of intense scrutiny over the past two decades 
because of the scientific and technological interest on 
the preparation method and nanostructure dependence 
of these properties [1-4]. Zirconia (ZrO2) is one of these 
materials that especially in the thin film form is very 
attractive. ZrO2 has been applied at thermal barrier 
coatings [5], optical filters and laser mirrors [6], alter-
native gate dielectrics in microelectronics [7, 8], a buff-
er layer for a high Tc ceramic superconductor on Si [9], 
high temperature oxygen separation [10], oxygen sen-
sors [11] and fuel cells [12] due to its heat resistance, 
low thermal conductivity, a relative high dielectric con-
stant, high refractive index, high transparency in the 
visible and near-infrared region [13, 14]. In all these 
practical applications, the preparation method, control 
of growth, crystal structure, chemical composition, and 
electronic properties of ZrO2 thin films are very im-
portant. Hence, characterization of structural, electrical, 
mechanical and optical properties of Zirconia thin films 
prepared using different deposition techniques and cor-
relation between nano-structure and different properties 
of these films play an important role in their technical 
applications. Many researchers have been reported on 
investigation of different properties of ZrO2 thin films 
prepared by different methods including thermal anneal-
ing [15, 16], sputtering [17, 18], reactive sputtering 
[19, 20], Chemical Vapor Deposition [21], electron beam 
evaporation [22], and sol-gel processing [23]. 
In this work, in order to more deeply understand 
the effect of annealing conditions on the Zr thin films, 
we have prepared the Zirconium oxide thin films by 
post-annealing of Zr / Si films at different temperatures 
and times, and studied the influence of these variables 
on crystallographic structure, surface morphology, 
chemical composition and electrical and mechanical 
properties of these layers. 
 
2. EXPRIMENTAL DETAIL 
 
Conventionally polished silicon (Si (400), n-type) 
with dimensions of 20  20 mm2 were used as a sub-
strate. The substrates were cleaned with acetone and 
ethanol in ultrasound cleaner for several minutes and 
were dried by argon gas flow. Zr thin films of 90 nm 
thickness were deposited by means of DC magnetron 
sputtering system using a circular sputtering target 
(99.998 % purity) of 76 mm diameter and 1 mm thick-
ness. The target to substrate distance was 10 cm. A 
continuously variable DC power supply of 600 V and 
150 mA was used as a power source for sputtering. 
The thickness and deposition rate of the Zr films were 
checked in situ using a quartz crystal monitor (6 MHz 
gold, Inficon Company, USA) located near the sub-
strate during the sputtering process. Zirconium thin 
films were deposited at a deposition rate of 9 Å/s. The 
base pressure was 4  10 – 5 mbar, achieved with a 
diffusion pump coupled with a rotary pump that was 
changed to 2.8  10 – 3 mbar after presence of Argon. 
The purity of argon gas in this work was 99.998 % and 
controlled by mass flow controller. Post-annealing of 
Zr / Si films were performed by a tube furnace at five 
 K. KHOJIER, S. SARSHAR, F. JAFARI, A. BORZOU PROC. NAP 2, 01NTF06 (2013) 
 
 
01NTF06-2 
different temperatures (150 to 750 C in steps of 
150 C) with flow of oxygen (purity of 99.98 %) at 
200 sccm (standard cubic centimeter per minute). Two 
annealing times of 60 and 180 min were used. The 
samples were reached the selected annealing temper-
ature with a thermal gradient of 5 degree/min, and 
then gradually cooled down to room temperature. The 
details of the samples produced in this work are given 
in Table 1. Nanostructure and crystallographic orien-
tation of the samples were obtained using a Philips 
XRD X’pert MPD Diffractometer (Cu Kα radiation, 
40 kV and 30 mA) with a step size of 0.02° and count 
time of 1 s per step. A Field Emission Scanning Elec-
tron Microscope FESEM (model: CamScan MV2300, 
Czech & England) and an Atomic Force Microscope 
(Auto probe PC, Park Scientific Instrument, USA) 
were also employed for investigation of chemical com-
position and surface morphology, respectively. The 
electrical resistance of films was also measured by two 
probe instrument with an excitation wavelength at 
320 nm, while films hardness was measured by nano-
indentation test. 
 
3. RESULT AND DISCOSION 
 
Fig. 1 shows X-ray diffraction patterns of Zr / Si 
thin films annealed at different temperature for 
60 min. XRD pattern of annealed sample at 
150 Cshows two peaks at 31.91 and 34.25 can be 
related to ZrO2 (012) and ZrO2 (111) diffraction lines of 
orthorhombic phase (with reference to JCPDS Card 
No.: 33-1483, and 2: 31.889 and 34.222). By in-
creasing of annealing temperature to 300 C, men-
tioned peaks of orthorhombic phase are omitted and 
three new peaks are observed at 28.05, 29.81, and 
34.23. These peaks can be attributed to ZrO2 (111) 
crystallographic orientation of monoclinic phase (with 
reference to JCPDS Card No.: 05-0543, and 2: 
28.036), ZrO2 (101) crystallographic orientation of 
tetragonal phase (with reference to JCPDS Card No.: 
24-1164, and 2: 29.807), and ZrO2 (002) crystallo-
graphic orientation of monoclinic phase (with refer-
ence to JCPDS Card No.: 05-0543, and 2: 34.195), 
respectively. With increasing of annealing tempera-
ture to the higher temperatures (450, 600 and 750 C) 
don’t observe any new peaks. On the other hand, it 
can be concluded that the annealing temperature (in 
the range of 300-750 C) have little influence on the 
structure of ZrO2 films. The above mentioned behavior 
was also observed for annealed samples at higher an-
nealing time (i.e., samples S6-S10). The XRD results 
detail of all samples are given in Table 1. It can be 
seen in column 4 of Table 1, that the position of all 
diffraction lines are shifted to higher diffraction an-
gles relative to that of powder sample with increasing 
the annealing temperature. In addition those samples 
annealed at higher time (i.e. 180 min) show larger 
shift than those annealed at 60 min. These behaviors 
can be related to increasing of tensile stress by in-
creasing of annealing temperature and time. The ten-
sile stress can be also attributed to higher thermal 
expansion coefficient of ZrO2 to Si that increases at 
higher annealing temperatures and time. 
In order to obtain the crystalline size (coherently 
diffracting domains) of the samples we used the Scher-
rer relation [24]: 
 
 
cos
k
D
B


   
 
where,  is the wavelength of X-ray,  is the Bragg 
angle, and k is a dimensionless constant which is re-
lated to the shape and distribution of crystallites [25] 
(usually taken as unity). For obtaining the value for, 
we used the usual procedure of full width at half max-
imum (FWHM) measurement technique [26], there-
fore: 
 
  
1
2 2 2
0 iB W W    
 
where, W0 is the FWHM of the sample and Wi is the 
FWHM of stress free sample (standard SiO2 single 
crystal sample). The calculated crystalline size, D ob-
tained from the above procedure is given in column 5 of 
Table 1. This result shows that the increasing of an-
nealing temperature and time cause the increasing of 
crystalline size in these films. This behavior may be 
due to high annealing temperature / more annealing 
time that provides energy of film atoms to enhance mo-
bility. Increasing of mobility can also increases the coa-
lescence and decreases the defects and cause the im-
provement of pores and quality of ZrO2 films. 
 
 
 
Fig. 1 – XRD patterns of Zr / Si thin films annealed at differ-
ent temperatures for 60 min 
 
3D AFM images of selected samples (annealed at 
different temperatures for 60 min) are shown in Fig. 2. 
The grains size (calculated by JMicrovision code from 
2D AFM images) and surface roughness of all samples 
are plotted in Fig. 3 and 4, respectively. These results 
show that an increase in annealing temperature and 
time caused increasing grains size (consistent with 
XRD results) and surface roughness. Increasing of sur-
face roughness can be related the increasing of grains 
size as mentioned before.  
 
 NANO-STRUCTURAL, ELECTRICAL AND MECHANICAL CHARACTERIZATION… PROC. NAP 2, 01NTF06 (2013) 
 
 
01NTF06-3 
Table 1 – Detail of XRD analysis 
 
 T,(C) T,(min) 2 (deg.), (hkl) D, (nm) 
S1 150 60 31.89 / 34.23 
O(012) / O(112) 
33 / 37 
S2 300 60 28.05 / 29.81 / 34.21 
M(111) / T(101) / M(002) 
61 / 65 / 64 
S3 450 60 28.07 / 29.83 / 34.23 
M(111) / T(101) / M(002) 
83 / 81 / 87 
S4 600 60 28.07 / 29.83 / 34.25 
M(111) / T(101) / M(002) 
97 / 95 / 102 
S5 750 60 28.09 / 29.85 / 34.27 
M(111) / T(101) / M(002) 
133 / 159 /  
151 
S6 150 180 39.91 / 34.25 
O(012) / O(112) 
42 / 46 
S7 300 180 28.07 / 29.83 / 34.21 
M(111) / T(101) / M(002) 
64 / 68 / 71 
S8 450 180 28.09 / 29.85 / 34.23 
M(111) / T(101) / M(002) 
89 / 88 / 93 
S9 600 180 28.09 / 29.87 / 34.27 
M(111) / T(101) / M(002) 
107 / 110 /  
115 
S10 750 180 28.09 / 29.87 / 34.29 
M(111) / T(101) / M(002) 
147 / 162 /  
157 
 
 
 
Fig. 2 – AFM images of Zr / Si thin films annealed at different 
temperatures for 60 min 
 
The chemical composition of films was investigated 
by EDAX analysis. The results obtained from this anal-
ysis are shown in Fig. 5. These results show that ratio 
of O / Zr increases with increasing of annealing tem-
perature and time. On the other hand, increasing of 
annealing temperature in the range of 150-750 C, and 
annealing time improve the oxidation process. 
Variation of electrical resistance of Zirconium oxide 
thin films obtained from two probe instrument for selected 
samples (annealed for 60 min) is shown in Fig. 6. The re-
sult shows that an increase in annealing temperature 
results increasing of films electrical resistance. It can be 
due to the increasing of oxygen vacancies in films body 
with increasing of annealing temperature. 
Detail of hardness values of films is shown in Fig. 7. 
It can be seen that films hardness decreases with in-
creasing of annealing temperature and time. This re-
duction can be related to increasing of crystalline size 
and surface roughness with annealing temperature and 
time (according to XRD and AFM results).  
 
 
Fig. 3 – Variation of grain size of zirconium oxide thin films 
prepared at different times as a function of annealing temper-
ature 
 
 
 
Fig. 4 – Variation of surface roughness of zirconium oxide thin 
films prepared at different times as a function of annealing 
temperature 
 
 
 
Fig. 5 – The ratio of O / Zr in zirconium oxide thin films pre-
pared at different times as a function of annealing tempera-
ture 
 
1
10
100
1000
10000
100000
1000000
10000000
0.001 0.01 0.1 1 10
V (V)
I 
(n
A
)
150 °C
300 °C
450 °C
600 °C
700 °C
 
 
Fig. 5 – Variation of current as a function of voltage of Zr / Si 
thin films annealed at different temperature and time 
 
In a polycrystalline film, grain size has a tremen-
dous influence on the mechanical properties. Because 
grains usually have various crystallographic orienta-
tions, grain boundaries arise, while an undergoing de-
formation, slip motion will take place. Grain bounda-
ries act as an impediment to dislocation motion for the 
 K. KHOJIER, S. SARSHAR, F. JAFARI, A. BORZOU PROC. NAP 2, 01NTF06 (2013) 
 
 
01NTF06-4 
following two reasons: (1) dislocation must change its 
direction of motion due to the different orientations of 
grains; (2) discontinuity of slip planes from one grain to 
another [27]. It is also reported that film hardness and 
surface roughness have an inverse relation [28], so that 
the films with more surface roughness may possibly 
have an open and porous structure, which leads to low-
er hardness. 
 
 
 
Fig. 6 – Variation of hardness of zirconium oxide thin films 
prepared at different times as a function of annealing temper-
ature 
 
4. CONCLUSION 
 
Zirconium Oxide thin films prepared by post-
annealing of Zr / Si (400) thin films (with 90 nm thick-
ness) at different annealing temperatures (150-750 C) 
and  different annealing times (60 and 180 min) were 
studied. Nanostructure and surface morphology of 
these layers were considered by XRD, AFM techniques, 
when the chemical composition of the films were inves-
tigated by EDAX analysis. The electrical resistance and 
films hardness were measured by a two probe instru-
ment and nano-indentation test. The results showed:  
I) The films annealed at 150 C were a polycrystal 
of orthorhombic phase, while samples annealed at 
higher temperatures (300 -750 C) showed a mixed 
structure of monoclinic and tetragonal.  
II) Increasing of annealing temperature and time 
caused increasing of crystalline size, surface roughness, 
ratio of O / Zr in the films. 
III) An increase in annealing temperature and time 
caused increasing of electrical resistance that was re-
lated to increasing of oxygen vacancies in films struc-
ture. 
IV) The hardness of zirconium oxide thin films de-
creased with increasing of annealing temperature and 
time that were due to the increasing of grains size and 
surface roughness with these variables. 
 
AKNOWLGMENT 
 
This work was carried out with the support of the 
Islamic Azad University, Chalous branch and Central 
Tehran Branch. The authors are grateful to Prof. 
H. Savaloni.
 
REFERENCES 
 
1. A.N. Banerjee, K.K. Chattopadhyay, J. Appl. Phys. 97, 
084308 (2005). 
2. A.V. Morozovska, E.A. Eliseev, Phys. Rev. B 73, 104440 
(2006). 
3. D. Katz, T. Wizansky, O. Millo, E. Rothenberg, T. Mokari, 
U. Banin, Phys. Rev. Lett. 89, 086801 (2002). 
4. K. Khojier, H. Savaloni, Vacuum 84, 770 (2010). 
5. S.M. Meier, D.K. Gupta, J. Eng. Gas Turbines Power 
Trans. ASME 116, (1994) 250. 
6. W.H. Lowdermilk, D. Milam, F. Rainer, Thin Solid Films 
73, 155 (1980). 
7. M. Copel, M. Gribelyyuk, E. Gusev, Appl. Phys. Lett. 76, 
436 (2000). 
8. M. Houssa, V.V. Afanas’ev, A. Stesmans, M.M. Heyns, 
Appl. Phys. Lett. 77, 1885 (2000). 
9. D.K. Fork, D.B. Fenner, G.A.N. Connell, J.M. Phillips, 
T.H. Geballe, Appl. Phys. Lett. 57, 1137 (1990). 
10. J. Han, Y. Zeng, G. Xomeritakis, Y.S. Lin, Solid State Ion-
ics 98, 63 (1997). 
11. M. Sayer, K. Sreenivas, Science 247, 1056 (1990). 
12. N.Q. Minh, J. Am. Ceram. Soc.76, 563 (1993). 
13. P. Baumeister, O. Arnon, Appl. Opt. 16, 439 (1977). 
14. M.A. Russak, C.V. Jahnes, E.P. Katz, J. Vac. Sci. Technol. 
A 7, 1248 (1989). 
15. P.Y. Kuei, J.D. Chou, C.T. Huang, H.H. Ko, S.C. Su,  
J. Cryst. Growth 314, 81 (2011). 
16. J. Ciosek, W. Paszkowicz, P. Pankowski, J. Firak, 
U. Stanislawek, Z. Patron, Vacuum 72, 135 (2004).   
17. A.P. Huang, P.K. Chu, Mat. Sci. Eng. 121, 244 (2005). 
18. L.F. Cueto, E. Sanchez, L.M. Torres-Martinez, 
G.A. Hirata, Mater Charact. 55, 263 (2005). 
19. B.J. Lee, H.L. Sohn, Y.T. Cho, J. Korean Phys. Soc. 51, 
1038 (2007). 
20. L.D. Huy, P. Laffez, P. Daniel, A. Jouanneaux, N.T. Khoi, 
D. Simeone, Mat. Sci. Eng. B: Solid. 104, 163 (2003). 
21. J.J. Yu, I.W. Boyd, Appl. Surf. Sci. 208-209, 374 (2003). 
22. Y.M. Shen, S.Y. Shao, H. Yu, Z.X. Fan, H.B. He, J.D. Sha, 
Appl. Surf. Sci. 254, 552 (2007). 
23. W.C. Liu, D. Wu, A.D. Li, H.Q. Ling, Y.F. Tang, 
N.B. Ming, Appl. Surf. Sci. 191, 181 (2002). 
24. B.E. Warren, X-ray Diffraction (Addison Wesley Publish-
ing Co.: London: 1969). 
25. J.I. Langford, A.J. Wilson, J. Appl. Cryst. 11, 102 (1978).  
26. T.C. Huang, G. Lim, F. Parmigiani, E. Kay, J. Vac. Sci. 
Technol. A 3, 2161 (1985). 
27. T.G. Wang, D. Jeong, Y. Liu, Q. Wang, S. Iyengar, 
S. Melin, K.H. Kim, Surf. Coat. Technol. 206, 2638 (2012). 
28. K. Koski, J. Holsa, P. Juliet, Surf. Coat. Technol. 120-121, 
303 (1999). 
 


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Nano-structural, Electrical and Mechanical Characterization of Zirconium Oxide Thin Films as a Function of Annealing Temperature and Time

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