Synthesis and Characterization of nickel oxide thin ...

1 downloads 0 Views 1MB Size Report
Apr 12, 2014 - At the same time, the optical gap ... values in the range of 10 – 90 °. .... The optical method was used to determine the band gap of the produced ...
Accepted Manuscript Title: Synthesis and Characterization of nickel oxide thin films deposited on glass substrates using spray pyrolysis Author: M. Jlassi I. Sta M. Hajji H. Ezzaouia PII: DOI: Reference:

S0169-4332(14)00908-8 http://dx.doi.org/doi:10.1016/j.apsusc.2014.04.134 APSUSC 27734

To appear in:

APSUSC

Received date: Revised date: Accepted date:

1-8-2013 12-4-2014 18-4-2014

Please cite this article as: M. Jlassi, H. Ezzaouia, Synthesis and Characterization of nickel oxide thin films deposited on glass substrates using spray pyrolysis, Applied Surface Science (2014), http://dx.doi.org/10.1016/j.apsusc.2014.04.134 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

• Highlights • Nickel oxide was prepared on glass substrate by using spray pyrolysis technique.

ip t

• Ameliorate the adherence of films with the variation of the substrate temperature. • We have studied the effects of the pulverization time on the physical properties.

Ac ce p

te

d

M

an

us

cr

• Amelioration on morphological and optical properties of the nickel oxide films.

1    Page 1 of 28

Synthesis and Characterization of nickel oxide thin films deposited on glass substrates using spray pyrolysis M. Jlassi *1, I.Sta 1, M.Hajji 1, 2, and H. Ezzaouia 1

ip t

1 Laboratoire de Photovoltaïque, Centre de Recherche et des Technologies de l’Energie, Technopole de Borj-Cédria, BP 95, 2050 Hammam-Lif, Tunisia.

cr

2 Ecole Nationale d’Electronique et des Communications de Sfax, Technopole de Sfax, BP 1163, CP 3021, Tunisia.

Email of corresponding author: [email protected] 

us

*

an

Abstract

A simple and inexpensive spray pyrolysis technique was employed to deposit nickel oxide

M

(NiO) thin films from hydrated nickel chloride salt solution onto amorphous glass substrate. The as-deposited films were transparent, uniform and well adherent to the glass substrate. The

d

effect of the substrate temperature, the volume and the concentration of the sprayed solution

te

on the structural, optical and electrical properties was studied using X-ray diffraction, optical transmittance, four point probe, scanning electron microscopy and atomic force microscopy.

Ac ce p

The structural analyses show that all the samples have a cubic structure. It was found that the increase in the volume of sprayed solution leads to an increment in the crystallite size of NiO and improves the homogeneity of the film. Optical measurements have shown that an increase in the thickness of the layer results in a decrease in the optical transmission, but it remains higher than 70 % even if the thickness exceeds 600 nm. At the same time, the optical gap decreases from 3.7 to 3.55 eV when the thickness increases from 133 to 620 nm. Low values of the electrical resistivity (less than 10 Ω.cm) were obtained for thin films with thicknesses less than about 240 nm, but for higher thicknesses the resistivity increases linearly to reach about 170 Ω.cm for a thickness of 620 nm. Keyword: Spray pyrolysis; Nickel oxide; thin films; Characterization. 2    Page 2 of 28

1. Introduction Transparent conducting oxides (TCO) have been widely studied due to their wide applications such as transparent electrodes for liquid crystal displays, light-emitting diodes and solar cells

ip t

[1, 2]. For large scale opto-electronic device applications, transparent conducting p-type oxide semiconductors are mostly required, nickel oxide (NiO) is an interesting candidate of this

cr

class with low p-type conductivity [3–5]. NiO is a semiconductor compound, having an

us

energy gap of 3.6 – 4.0 eV [3]. Although, stoichiometric NiO material is an isolator [5], the resistivity of NiO thin films can be lowered by the increase of Ni vacancies and/or interstitial

an

oxygen in NiO crystallites [5]. So, NiO thin films are also interesting for a variety of other applications, such as, the antiferromagnetic material [6]; an active material in chemical gas

M

sensors [7]. It can also be used as a material for electrochromic display devices and in other optoelectronic devices such as elements for information display, light shutter and variable

d

reflectance mirrors [8]. For the fabrication methods, sol–gel [9], spray pyrolysis [10],

te

chemical self-assembling [11]; pulsed laser deposition [12-14] and magnetron sputtering [1517] were widely used to grow NiO thin films. Among these methods, the spray pyrolysis is

Ac ce p

especially suitable, since it had been proved to be a simple and inexpensive method, particularly useful for large area applications [18, 19]. This method is cheap, simple and permits the preparation of the films with the required properties for optoelectronic applications. NiO thin films have been focus on excellent optical and electrical property. It were used for a promoter layer photoelectrode and dye-sensitized solar cell devices [1]. In this paper, we report on the properties of spray deposited NiO films grown under different conditions. A detailed study on the role of the deposition conditions and in particular the influence of the film thickness on the structural, optical and electrical properties of NiO thin films were carried out. The obtained results provide useful information about properties

3    Page 3 of 28

evolution which is an important issue for better understanding and improvement of the material quality for the fabrication of NiO - based devices.

ip t

2. Experimental details High purity nickel (II) chloride hexahydrate (NiCl2·6H2O; 99.999 %; Sigma-Aldrich) was

cr

used as precursor for the preparation of NiO thin films using the spray deposition technique.

us

The nickel chloride was dissolved in deionized water to prepare spray solutions with concentrations of 0.05 and 0.1 M. The spray solution was then sprayed in fine droplets onto

an

glass substrates at a temperature of 350 or 450 °C. Nitrogen was used as the carrier gas. Before deposition the substrates were ultrasonically cleaned in acetone, rinsed with deionized

M

water and dried in oven for 10 min at 100 °C. The injection rate of the precursor solution using a syringe pump was varied between 2 and 10 ml/min. The N2 pressure was 1.5 105 Pa,

d

resulting in an air flow through the nozzle of approximately 20 l/min and the nozzle to

te

substrate distance was of 15 cm. The two substrate temperatures were used at 350 °C and 450°C. Films with various thicknesses were obtained by varying the duration of pulverization

Ac ce p

from 5 to 20 minutes.

The crystallographic structure was studied by X-ray diffraction XRD technique using a Bruker D 8 advance X-ray diffractometer with Cu Kα (k = 1.5418 Å) a radiations for 2θ values in the range of 10 – 90 °.The Surface morphology of the prepared films was characterized via atomic force microscopy (AFM) in tapping mode configuration by a Nanoscope III. The surface and the cross-section view of thin films were observed by Scanning Electron Microscopy (SEM) (FEG-SEM JEOL 7400F) was operated at 30 kV. The thickness of the film was measured using SEM image. The thicknesses were measured in different points because the films produced by spray method do not have homogeneous 4    Page 4 of 28

surface. The optical transmittance T (λ) and the reflectance R (λ) of the films were measured by UV–vis–NIR (Lambda 950) spectrophotometer, equipped with an integrating sphere, in the wavelength range 300–2500 nm. The electrical resistivities were measured at room

ip t

temperature by using a four-point probe Van der Pauw configuration (S302-X). All the

cr

measurements were carried out at room temperature.

us

3. Results and discussion 3.1. Structural properties

an

XRD was used to study the effect of the substrate temperature, the spray solution concentration and the pulverization duration on the structural properties of NiO thin films.

M

The XRD patterns presented in Fig. 1 show the effect of substrate temperature on the structural properties of NiO thin films prepared at a fixed molarity of 0.05 M for different

d

durations of pulverization. The peak located at 37.31° is the (111) diffraction peak from cubic

te

structure of NiO, the peak located at 81.7° is the (002) diffraction peak from cubic structure of NiO, the peak located at 43.31° is not very clear when the substrate temperature is increased

Ac ce p

to 450 °C. Results show that the films are polycrystalline, consisting of NiO cubic phase with preferred orientation along (111) direction, which is the most suitable direction for ion exchange [20], and a weak reflection along (002) plane. In the other hand the intensity of (111) peak is increased at the substrate temperature of 450 °C. Fig. 2 shows the XRD results obtained for NiO thin films prepared at different molarities and duration of pulverization at a substrate temperature of 350 °C. All samples exhibited peaks at (111) and (002), were indexed precisely to a cubic structure of NiO [9]. Fig. 3 presents the effect of the deposition time on the structure of the films obtained for a substrate temperature of 350 °C and a

5    Page 5 of 28

molarity of 0.05 M. It was found that all samples were polycrystalline consisting of NiO cubic phase, comprising a strong reflection along (111) plan and a weak reflection along (002) plan. The crystallite size of the NiO films was calculated, from the peaks with the highest intensity,

kλ     β cosθ

 

(1)

cr

D=

ip t

using the Scherrer’s equation [21]:

Where λ, θ and β are the X-ray wavelength, Bragg diffraction angle and full width at half

us

maximum, respectively, D is the grain size.

Tab.1 shows the variation of the crystallite size, of NiO thin films developed by spray

an

pyrolysis technique, with the deposition parameters. We noticed that the crystallite size

M

increases with the substrate temperature increase and decreases by increasing the duration of pulverization for the films obtained with 0.05 M solution.

d

3.2 Morphological properties

te

In macroscopic scale, the resulting NiO thin films prepared at a substrate temperature of 350 °C were found to be homogenous, transparent and strongly adherent to the substrates. But, by

Ac ce p

increasing the substrate temperature to 450 °C the NiO layers become relatively inhomogeneous. So, the study will be focused on the properties of thin films prepared at substrate temperature of 350 °C. The SEM images shown in Fig. 4 indicate that the films present a porous structure which becomes more dense, smooth, and more homogeneous when the volume of the pulverized solution increases. For low duration of pulverization it is observed that the substrate is well covered by a non-uniform film of NiO. Some nanosheets are developed on the film, this may be due to the evaporation of the solvent (H2O, HCl) from the film [22]. Nanosheets were observed only on some regions of the substrate, indicating less uniform growth. Moreover, the nanosheets exhibit a rough surface area. Increasing the duration of pulverization to 20 minutes (Fig. 4 (c)) results in the formation of more uniform 6    Page 6 of 28

and smoother nanosheets than those obtained with a duration of pulverization of 5 minutes (Fig. 4 (a)). The porous structure of NiO thin films elaborated by the simple spray deposition technique, suitable for large area coating, is very interesting for photocatalysis and gas

ip t

sensing applications. In such structure more paths are available for gas molecules diffusing in the structure leading to an increase in the sensitivity of the layer [23]. The deposited films

cr

were nearly transparent and the estimated thickness was determined by SEM cross section analysis. The results of the thickness of NiO thin films are presented in Fig. 5. AFM was used

us

to examine the external topography of the surface of NiO thin films deposited from solutions

an

with different molarities at different durations of pulverization and a substrate temperature of 350 °C. To evaluate the surface roughness as well as the grain size of the films, an area of 20

M

µm×20 µm has been scanned in tapping mode. Standard software was used to calculate rootmean-square (RMS) roughness. The AFM images reveal that the solution molarity and the

d

substrate temperature have a strong effect on the surface morphology. The obtained AFM

te

images for NiO thin films elaborated from a spray solution with a molarity of 0.1 M for durations of pulverization of 5 and 12 minutes, and a substrate temperature of 350 °C are

Ac ce p

presented in Fig. 6. It can be seen that all the samples are uniform and have nanosheets structures. The nanosheets have a mixture of porous microstructures. By decreasing molarity to 0.05 M and keeping the same substrate temperature the films become more uniform as shown in Fig. 7 (a) and 7 (b). In contrast, the NiO films prepared at solution molarity of 0.05 and a substrate temperature of 450 °C have more complex and inhomogeneous surface structure (Fig. 7(c) and 7(d)). The RMS roughness (Fig. 8) increases when the duration of pulverization increases. This increase in the RMS can make NiO films elaborated by the simple spray deposition technique, very interesting for gas sensing application. Steinebach et al. reported in their study on H2 gas sensor performance of NiO that the highest surface roughness leads to the highest gas sensing response [24]. 7    Page 7 of 28

3.3 Optical properties Spectral transmittance and reflectance are shown in Fig. 9 (a). It is clear that the obtained films exhibit high transparencies in the visible spectral region. The transmission decreases

ip t

when the duration of pulverization increases. The films assemble a transmission between 90 and 70 % that decreases by increasing the duration of pulverization. In addition, the

cr

reflectivity (Fig. 9 (b)) is below 20 %, which proves the transparency of our NiO films.

us

The optical method was used to determine the band gap of the produced ZnO film. In the optical method, the band gap values are obtained by from the following relation [25]: 1

α hυ = A ( hυ − E g ) 2

an

. (2)

Where A is a constant, α is the absorption coefficient, hυ is the photon energy and Eg is the

M

band gap energy. For Eq. (2) the transition data provide the best linear curve in the band edge region, implying the transition is direct in nature. The determination of the band gaps of the

d

films have been calculated using Tauc’s plot of ( αhυ ) ² versus hυ and by extrapolating the

te

linear portion of the absorption edge to find the intercept with energy axis as shown in Fig.

Ac ce p

10. The estimated optical band gap energy decreases from 3.7 to 3.55 eV with an increase in the duration of the deposition of the NiO films. The increase in the deposition time leads to the incorporation of more oxygen atoms in the film. Incorporated oxygen atoms can replace either substitutional or interstitial sites in the NiO lattice creating the structural deformation. The introduction of more oxygen atoms creates some additional energy levels in the NiO band gap close to the valence band edge, with a subsequent reduction of the energy associated with the indirect transition of the films elaborated with higher deposition times [26]. Crystalline NiO bulk has a band gap of 4.0 eV [27, 28] which is much higher than the band gap values obtained for NiO films.

8    Page 8 of 28

3.4 Electrical conductivity The resistivity was measured by the Van der Pauw method (four point configuration) and its dependence with the duration of pulverization, for NiO films prepared using 0.05M spray

ip t

solution and a substrate temperature of 350 °C, is shown in Fig. 11. For all samples, it is observed that the resistivity increases with the increase in the duration of pulverization of the

cr

NiO thin films. Low values of the electrical resistivity (less than 10 Ω.cm) were obtained for

us

thin films with thicknesses less than about 240 nm, but for higher thicknesses the resistivity increases linearly to reach about 170 Ω.cm for a thickness of 620 nm. In these cases, an

an

increase in the resistance can be expected with an increase in the thickness [28]. As reported by many research groups [29, 30, 31] the electrical resistivity of the nickel oxide thin films is

M

located within the range of 10-106 Ω.cm. In this study the resistivity is more specifically located in the range of 10-200 Ω.cm depending on the deposition durations.

d

This raise of the resistivity with the increase of the thickness of the films can be attributed to

te

the modification of the surface morphology of NiO thin films, as shown in the AFM images of Fig. 7 (a) and 7 (b), and to the reduction in the crystallite size (table 1).The modification of

Ac ce p

the surface morphology can affect the stoichiometry of the NiO and the surface states leading to a change in the electrical properties of the films. The reduction of the crystallite size leads to an increase in the grain boundaries density. The increase of the resistivity with the decrease of crystallite size indicates that the conduction mechanism is driven by grain boundary

scattering. The obtained values for the electrical resistivity are much lower than the resistivity of the pure and stoichiometric nickel oxide which is of the order of 1013 Ω.cm [32]. The relatively low electrical resistivity of the NiO thin films in comparison with the pure NiO is generally attributed to the formation of the non-stoichiometric films with more or less oxygen [33]. In our case, the decrease of the band gap with increasing the deposition time 9    Page 9 of 28

suggests the formation of non-stoichiometric films with an excess of oxygen. The resistivity of the nickel oxide film can be lowered by an increase of the content of the Ni3+ ions and a

ip t

decrease of the content of metallic Ni in the NiO crystallite [27, 29].

4. Conclusions

cr

NiO thin films were deposited by the spray pyrolysis method. The effects of spraying

us

conditions on structural, morphological, optical and electrical properties of NiO thin films were investigated. All the deposited films are polycrystalline in nature. The AFM images of

an

the thin films showed that the surface morphology is affected by the spraying conditions. All films have a high transparency. The optical band gap has been found to decrease from 3.7 to

M

3.55 eV with the increase in spray time. This decrease was attributed to the formation of nonstoichiometric films with an excess of oxygen. This suggestion is in good agreement with the

d

relatively low values obtained for NiO thin films compared to pure NiO. The electrical

te

resistivity of the obtained NiO thin films is in the range of 10-200 Ω.cm depending on the deposition duration. The obtained properties of NiO thin films, such as transparency and

Ac ce p

homogeneity, make from the spray deposition method an important technique for the production of large area and low cost NiO thin films for many applications such as gas detection or antireflection coating for solar cells. However, further studies are needed for the improvement of electrical properties of NiO thin films for the application as TCO in thin film solar cells.

10    Page 10 of 28

References   [1] Yi-Mu Lee, Chun-Hung Lai, Solid-State Electronics 53 (2009) 1116 - 1125. [2] I-Min Chan, Franklin C. Hong, Thin Solid Films 450 (2004) 304 – 311.

ip t

[3] H.L. Chen, Y.M. Lu, W.S. Hwang, Surf. Coat. Technol. 198 (2005) 138 - 142. [4] U.S. Joshi, Y. Matsumoto, K. Itaka, M. Sumiya, H. Koinuma, Appl. Surf. Sci. 252(2006)

cr

2524 – 2528.

us

[5] J.A. Dirksen, K. Duval, T.A. Ring, Sens. Actuators B 80 (2001) 106 – 115.

[6] E. Fujii, A. Tomozawa, H. Torii, R. Takayama, Japanese Journal of Applied Physics 35

an

(1996) 328 - 330.

[7] I. Fasaki, A. Giannoudakos, M. Stamataki, M. Kompitsas, E. György, I.N. Mihailescu, F.

M

Roubani-Kalantzopoulou, A. Lagoyannis, S. Harissopulos, Applied Physics A 91 (2008) 487 492.

d

[8] K.S. Ahn, Y.C. Nah, Y.E. Sung, Appl. Surf. Sci.199 (2002) 259 - 269.

te

[9] Shweta Moghe, A .D. Acharya, Richa Panda, S.B. Shrivastava, Mohan Gangrade, T. Shripathi, V. Ganesan, Renewable Energy 46 (2012) 43 - 48.

Ac ce p

[10] Ulrich P. Muecke, Norman Luechinger, Lukas Schlagenhauf, Ludwig J. Gauckler, Thin Solid Films 517 (2009) 1522 - 1529. [11] Y. Wang, C. Ma, X. Sun, H. Li, Microporous Mesoporous Materials 71 (2004) 99 - 102. [12] B. Sasi, K.G. Gopchandran, Solar Energy Materials and Solar Cells 91 (2007) 1505 1509.

[13] Daniel Franta, Beatrice Negulescu, Luc Thomas, Pierre Richard Dahoo, Marcel Guyot, Ivan Ohlídal, Jan Mistrík, Tomuo Yamaguchi, Appl. Surf. Sci. 244 (2005) 426 – 430. [14] I. Fasaki, A. Koutoulaki, M. Kompitsas, C. Charitidis, Appl. Surf. Sci. 257 (2010) 429 433. [15] Y.M. Lu, W.S. Hwang, J.S. Yang, H.C. Chuang, Thin Solid Films 420 (2002) 54 – 61. 11    Page 11 of 28

[16] Duksu Kim, Mun-Kyu Kim, Jong-Tae Son, Ho-Gi Kim, Journal of Power Sources 108 (2002) 239 – 244. [17] Lei Ai, Guojia Fang , Longyan Yuan, Nishuang Liu, Mingjun Wang, Chun Li, Qilin

ip t

Zhang, Jun Li, Xingzhong Zhao, Appl. Surf. Sci. 254 (2008) 2401 – 2405. [18] D. A. Minkov, J. Phys. D: Appl. Phys. 22 (1989) 1157 - 1161.

cr

[19] B.A. Reguig, A. Khelil, L. Cattin, M. Morsli, J.C. Bernède, Appl. Surf. Sci. 253 (2007) 4330 - 4334.

us

[20] F.F. Ferreira, M.H. Tabacnicks, M.C.A. Fantini, I.C. Faria, A. Gorenstein, Solid State

an

Ionics 86 (1996) 971 - 976.

[21] B.D. Cullity. S.R. Stock, Elements of X-Ray Diffraction, 3rd ed., Prentice Hall, Upper

M

Saddle River, NJ (2001).

[22] Q.X. Xia, K.S. Hui, K.N. Hui, D.H. Hwang, S.K. Lee, W. Zhou, Y.R. Cho, S.H. Kwon,

d

Q.M. Wang, Y.G. Son, Materials Letters 69 (2012) 69 - 71.

te

[23] A. Mossad Ali and R. Najmy, Catalysis Today 208 (2013) 2 - 6. [24] H. Steinebach, S. Kannan, L. Rieth, F. Solzbacher, Sensors and Actuators B 151 (2010)

Ac ce p

162 - 168.

[25] J.M. Shah, Y.L. Li, T. Gessmann, E.F. Schubert, J. Appl. Phys. 94 (2003) 2627 - 2631. [26] P. Puspharajah, S. Radhakrishna, A. K Arof, Journal of Materials Science 32 (1997) 3001 - 3006.

[27] Z. M. Jarzebski, Oxide Semiconductors, Pergamon Press, Oxford. 150 (1973) 184. [28] D. Adler, J. Feinleib, Phys. Rev. B2 (1970) 3112 - 3134. [29] H. Sato, T. Minami, S. Takato, T. Yamada, Thin Solid Films 236 (1993) 27 - 31. [30] A.J. Varkey, A.F. Fort, Thin Solid Films 235 (1993) 47 - 50. [31] D. Adler, L.H. Tjeng, F.C. Voogt, T. Hibma, G.A. Sawatzky, C.T. Chen, J. Vogel, M. Sacchi, S. Iacobucci, Phys. Rev. B: Cond, Mater. Phys. 57 (1998) 11623. 12    Page 12 of 28

[32] M.B. Konovalov, V.I. Bystrov, V.L. Kubasov, Elektrokhimiya 12 (1976) 1266.

Ac ce p

te

d

M

an

us

cr

ip t

[33] P.S. Patil, L.D. Kadam, Appl. Surf. Sci. 199 (2002) 211 - 221.

13    Page 13 of 28

Figures captions Fig. 1 X-ray patterns of samples prepared for a molarity of 0.05 M and different substrate

temperatures of 350 °C (a) and 450 °C (b).

ip t

Fig. 2 X-ray patterns of samples obtained for substrate temperature of 350 °C and different

molarities of 0.05 M (a) and 0.1 M (b).

us

molarity 0.05 M and a substrate temperature of 350 °C.

cr

Fig. 3 X-ray patterns of samples prepared at different duration of pulverization at a fixed

Fig. 4 SEM micrographs of NiO thin films elaborated at different duration of pulverization (a)

an

5 min (× 1050) and (c) 20 min (× 1200), (b) (×6000) and (d) (× 36214) are the corresponding cross section view of the films.

M

Fig. 5 Evolution of the thickness of the NiO layers obtained by varying the duration of the

pulverization for a molarity of 0.05 and a substrate temperature of 350 °C.

d

Fig.6 AFM images of NiO thin films prepared at a molarity of 0.1M, a substrate temperature

te

of 350 °C and durations of (a) 5 and (b) 12 minutes. Fig. 7 AFM images of NiO thin films prepared at a molarity of 0.05 M, deposition times of 5

Ac ce p

and 12 minutes, and substrate temperatures of 350 °C (a and b) and 450 °C (c and d).

Fig. 8 Evolution of the  surface roughness of the NiO layers with the deposition time for

different conditions of pulverization.

Fig. 9 Spectral variations of transmission T (a) and reflectance R (b) for nickel oxide thin

films prepared at different spray times

Fig. 10 The dependence of (αhν) 2 on the incident photon energy hν for samples prepared at

different duration of pulverization. Fig. 11 The Resistivity of NiO thin films prepared at different duration of pulverization, at a

fixed molarity of 0.05 M and a substrate temperature of 350 °C.

14    Page 14 of 28

Tables captions Table 1 Effects of the concentration of the solution and the substrate temperature on

Ac ce p

te

d

M

an

us

cr

ip t

crystallite size of NiO thin films.

15    Page 15 of 28

Table 1 

Duration of the  pulverization (min)  5 

0.1 



350 

an



M

0.05 

0.05 

Ac ce p

te

d

450 

(Å) 

138 

us

12 

The crystallite size 

ip t

The solution concentration (mol/l)

cr

Substrate  temperature (°C) 

144  182  153 



146 

12 

145 



345 



290 

12 

169 

               

16    Page 16 of 28

Figure

Figure 1

(a)

350 °C

ip t

Intensity (arb.u)

12 min

20

30

40

50

60

(002)

an M

10

(111)

5 min

us

cr

8 min

70

80

90

ed

2-thetha (degree)

(b)

ce pt

450 °C

8 min

Ac 5 min

(002)

(111)

Intensity (arb.u)

12 min

10

20

30

40

50

60

70

80

90

2-thetha (degree)

Page 17 of 28

Figure 2

(a)

0.05 M

ip t

Intensity (arb.u)

12 min

20

30

40

50

60

(002)

an M

10

(111)

5 min

us

cr

8 min

70

80

90

ed

2-thetha (degree)

(b)

0.1 M

Intensity (arb.u)

ce pt

12 min

Ac

8 min

(002)

(111)

5 min

10

20

30

40

50

60

70

80

90

2-thetha (degree)

Page 18 of 28

Figure 3

20 min

0.05 M 350 °C

ip t cr

Intensity (arb.u)

15 min

an

us

12 min

20

30

40

50

(002)

ed

(111)

5 min

60

70

80

90

ce pt

2-thetha (degree)

Ac

10

M

8 min

Page 19 of 28

us

cr

ip t

Figure 4

ed

M

an

(a)

Ac

ce pt

133 nm

(b)

Page 20 of 28

ip t cr

ce pt

ed

M

620 nm

an

us

(c)

Ac

(d)

Page 21 of 28

Figure 5

700

600

ip t cr

400

us

300

100 4

8

12

an

200

16

20

ce pt

ed

M

Duration of pulverization (min)

Ac

Thickness (nm)

500

Page 22 of 28

Figure 6

5 min

(b)

Ac

ce pt

ed

M

an

us

cr

(a)

ip t

12 min

Page 23 of 28

Figure 7 5 min.

(a)

cr

(b)

ip t

12 min.

12 min.

M

an

us

5 min.

(d)

Ac

ce pt

ed

(c)

Page 24 of 28

Figure 8

80

ip t cr

60

50

us

450°C-0.05M 350°C-0.1M 350°C-0.05M

30 6

8

10

12

M

4

an

40

14

16

18

20

ce pt

ed

Deposition time (min)

Ac

RMS roughness (nm)

70

Page 25 of 28

Figure 9

100

(a)

ip t 5 8 12 15 20

min min min min min

cr

60

40

us

Transmittance (%)

80

0 400

600

800

1000

M

an

20

1200

1400

1600

1800

2000

2200

2400

Wavelength (nm)

25

5 8 12 15 20

20

min min min min min

Ac

Reflectance (%)

ed

(b)

ce pt

30

15

10

5 400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Wavelength (nm)

Page 26 of 28

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 10

Page 27 of 28

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 11

Page 28 of 28