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Investigation on the structural and optical properties of copper doped NiO nanostructures thin films
Materials Today: Proceedings xxx (xxxx) xxx
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Investigation on the structural and optical properties of copper doped NiO nanostructures thin films Ziad T. Khodair, Buthainah Abdulmunem Ibrahim ⇑, Mayada Kaream Hassan Department of Physics, College of Science, University of Diyala, Iraq
a r t i c l e
i n f o
Article history: Received 2 July 2019 Received in revised form 2 September 2019 Accepted 29 September 2019 Available online xxxx Keywords: NiO nanostructures Thin films Doping Optical properties Structural properties XRD AFM
a b s t r a c t In this research, copper is doped NiO nanostructures thin films by using various doping compositions (2, 4, 6 & 8%) have been prepared by chemical spray pyrolysis technique at a temperature of (400 °C). The optical, morphological and structural properties were investigated using UV–visible spectrophotometry, X-Ray diffraction (XRD) and atomic force microscopy (AFM). The results of (XRD) showed that all the prepared films are polycrystalline in nature with cubic structure with a strong (1 1 1) preferred orientation and the average crystallite size decreased with increase copper concentration, while the results of (AFM) indicate that the roughness of the surface decrease with increase doping. Enhancement of optical transmittance with doping decrease in the range (300–900 nm) was observed, and the absorption coefficient increased by increasing doping ratio, while the optical energy gap for allowing direct transmission decreased in the range (3.31 to 2.94 eV). Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Engineering & Science.
1. Introduction Nickel oxides is a transition metal oxide have main applications, such as sensors, smart window, electrodes for batteries [1]. NiO thin film can be produced by various techniques, which include, electrochemical, evaporation, spray pyrolysis and chemical techniques [2,3]. The use of nanomaterials is a new somehow area in the area of nanotechnology and nanoscience [4]. Nickel oxide is p-type semi-conducting with energy band gap (3.6–4 eV), and doped mineral oxide nanoparticles are salutary in a wide diversity of applications such as dilute magnetic semiconductors, photo detectors, optoelectronics [5,6]. Nickel oxide (NiO) is used in the manufacture of electric ceramics such as thermistors, and used as electrodes in optical and electronic devices and used in electrostatic sensor [7,8]. In this research, copper-doped NiO thin films was prepared, the structural, optical, and morphological properties were characterized using X-Ray diffraction, UV–visible spectrophotometry, and atomic force microscopy (AFM). 2. Experimental Copper-doped NiO nanostructures thin films (NiO:Cu) deposited on glass substrates using Nickel nitrate hex hydrate Ni (NO3)26H2O, ⇑ Corresponding author. E-mail address: [email protected] (B. Abdulmunem Ibrahim).
and copper nitrate trihydrate Cu (NO3) 23H2O. The deposition conditions of the all films were a between nozzle and substrate of 30 cm, interval spray of 2 min, spray time of 10 s and air pressure 1.3 bar. The (XRD) patterns were calculated from (a Shimadzu XRD-6000 company). The morphology of the films was characterized by Atomic force microscopy (AFM; SPM-AA3000) and (UV–Visible1800, Shimadzu). The thickness of the thin film is about (200 nm) calculated by using the following relation [9]:
t¼
DW qA
ð1Þ
Where, DW= (W2 W1), W1 denotes the weight of the substrate before the deposition and W2 denotes the weight of the substrate after deposition. A: The film area (cm2). q: density of film material (g/cm3). 3. Results and discussion 3.1. Structural properties The structural properties of (NiO: Cu) nanostructures thin films as shown in Fig. 1. The patterns of XRD are in good agreement with the ICDD card (04-0835), it is found that all the films were identified to be cubic structure with polycrystalline and the peaks diffraction are seen to be oriented at (1 1 1), (2 0 0) and (2 2 0)
https://doi.org/10.1016/j.matpr.2019.09.189 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Engineering & Science.
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
2
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 1. XRD patterns of NiO: Cu with various doping concentrations.
diffraction peaks. The preferred orientation doesn’t change when the copper-concentration increases. The lowest diffraction intensity peaks are found with an increase in the full width at half maximum (FWHM), that means the crystallization rate of the films decreases with the doping. The lack of crystallization rate can be explained by the type of chemical bond formed between the atoms
of the films material or by the specific heat of the solid body or by the difference of the melting points in the components of the material [10]. The average crystallite size (Dav) for (NiO: Cu) nanostructures thin films was calculated by the Scherrer relation for (1 1 1) preferred orientation and the relation [11,12].
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
3
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Structural parameters of NiO with various concentrations of Cu. Sample
2 H (deg)
d (Å)
hkl
NiO (ICCD) 04-0835
37.28 43.297 62.916
2.41 2.088 1.476
111 200 220
NiO-pure
37.1479 43.2166 62.8391
2.4183 2.0917 1.4776
NiO: Cu (2%)
37.14 43.1497 62.7284
NiO: Cu (4%)
FWHM (deg)
Dav (nm)
111 200 220
0.805
10.4
2.4188 2.0948 1.4799
111 200 220
0.52
10.41
37.1168 43.1252 62.684
2.4202 2.0959 1.4809
111 200 220
0.84
10
NiO: Cu (6%)
37.116 43.0564 62.6535
2.4203 2.0991 1.4815
111 200 220
1.01
8.3
NiO: Cu (8%)
37.11 43.056 62.5544
2.4206 2.0991 1.4836
111 200 220
0.97
8.6
Fig. 2. AFM images of (NiO: Cu) for doping concentrations a (0%) and b (2%).
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
4
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 3. AFM images of (NiO: Cu) for doping concentrations c (4%), d (6%) and e (8%).
Dav ¼
Kk bcosh
where: K: is shape factor depends on the shape of the material, b: The full width at half maximum (FWHM),
ð2Þ
k: Wavelength of X-ray, h: Bragg diffraction angle. The values of the average crystallite size are found to be within the range (10.4–8.3 nm), where the size decreases with increasing Cu doping concentration from (0% to 8%). copper and nickel have the same oxidation number of +2 but they marginally differ in ionic
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
radii because the ionic diameter of Cu+2 (0.73 Å) is very close to the ionic diameter of Ni+2 (0.69 Å) [13], which leads to the insertion of copper atoms as substitution atoms within the crystalline lattice. The values of (Dav) are found to be within in the nanoscale and structural parameters as shown in Table 1, so the (Dav) of the material plays an important role in determining the properties of the material.
Fig. 4, where transmittance decreases by increasing the rate of doping. This occurs due to the entry of copper atoms (Cu) which leads to additional levels formed at the bottom of the conduction band. The absorption coefficient of (NiO: Cu) nanostructures thin films was calculated by the following equation [12]:
a ¼ 2:303
3.2. Atomic force microscopy (AFM) AFM topography image of (NiO: Cu) nanostructures thin films provides information on droplet interaction with substrate glass and fairly agrees with the XRD results as shown in Figs. 2 and 3. The AFM images 2D and 3D indicated the formation of smaller grains with increasing Cu-substitution with distribution of granules on the surface of the films, also showed that NiO films are smooth and homogenous. The roughness surface values and Root Mean Square (RMS) decrease in range (12.6–1.85 nm) with the percentage of copper doping for all samples are shown in Table (2) and Table (3). 3.3. Optical properties The transmittance of (NiO: Cu) nanostructures thin films was calculated at the wavelength range (300–900 nm) as shown in
A t
ð3Þ
where: A: Absorption, t: thickness of the film (cm). The Fig. 5 shows (a) of all thin films as a function of wavelength. It depends on the energy of the photons and the semiconductor properties, which indicate that allowed electronic transitions are occurred due to the value of (a > 104 cm1). The optical energy gap for the electronic direct allowed transition of (NiO: Cu) nanostructures thin films are calculated by using relation (4), where the value of (r = 1/2). Fig. 6 shows the relation between (hma)2 and (hm). The value of the energy gap of the undoped NiO films is (3.33 eV), the energy gap decreases as increasing doping ratio as (3.31, 3.26, 3.15, 2.94 eV) at (2%, 4%, 6%, 8%) concentrations respectively. The reason is due to the formation of local levels close to the conduction band contributed to increase the electrons number of that reach the conduction band. This indicates that copper ions are compensated for the original matter ions in the crystalline structure of the NiO [14,15].
ahm ¼ Aðhm EgÞn
Table 2 Surface roughness and RMS for Cu-doped NiO.
5
ð4Þ
where,
Sample
Surface roughness (nm)
RMS (nm)
NiO-pure NiO: Cu (2%) NiO: Cu (4%) NiO: Cu (6%) NiO: Cu (8%)
11.1 0.37 1.02 1.08 1.63
12.6 0.43 1.18 1.3 1.85
Table 3 Energy gaps for allowed transition.
direct
Sample
Eg (eV)
NiO-pure Ni: Cu (2%) Ni: Cu (4%) Ni: Cu (6%) Ni: Cu (8%)
3.33 3.31 3.26 3.15 2.94
Fig. 4. The transmittance spectra for Cu-doped NiO.
(Eg): The energy gap, A: the constant depending on the structure of the material, while the exponent (r) depends on the type of transition. 4. Conclusions In summary, we have firstly prepared (NiO: Cu) nanostructures thin films by using various doping compositions (2, 4, 6 & 8%). The effect of copper doping on crystallinity, morphological and optical properties was investigated. XRD patterns indicate that all films are cubic structure with polycrystalline and preferred orientation at (1 1 1), which doesn’t change when the copper doping increases. the average crystallite size decreases with increasing Cu doping concentration from (0% to 8%). The AFM results showed that the roughness surface values and (RMS) decrease with increase of the percentage of copper doping. The optical energy band gap
Fig. 5. The absorption coefficient for Cu-doped NiO.
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
6
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 6. Optical energy gap for NiO for Cu-doped NiO.
and transmittance values were found to decrease. The absorption coefficient (a) of the copper doped NiO at different copper doping levels has (a > 104 cm1) which indicates the increase of the probability of the occurrence of direct allowed transition. References [1] [2] [3] [4]
S. Sagadevana, S. Rajeshb, I. Dasc, Mater. Today:. Proc. 4 (2017) 4123–4129. S.A. Mahmoud, A.A. Akl, H. Kamal, K. Abdel-Hady, Phys. B 311 (2002) 366. J.K. Kang, S.W. Rhee, Thin Solid Films 391 (2001) 57. A.H. Abed, Z.T. Khodair, T.M. Al-Saadi, T.A. Al-Dhahir, AIP Conf. Proc. 2123 (2019) 020019. [5] Z.T. Khodair, A.A. Kamil, Y.K. Abdalaah, Physica B 503 (2016) 55–63.
[6] A.H. Abed, T.M. Al-Saadi, Z.T. Khodair, ARPN J. Eng. Appl. Sci. 13 (2018) 8049– 8054. [7] D. Franta, B. Negulescu, Thomas, P.R. Dahoo, M. Guyot, I. Ohlídal, J. Yamaguchi, T. Mistrík, Appl. Surf. Sci. 244 (2005) 426–430. [8] S.S. Ahmed, E.K. Hassan, G.H. Mohamed, Int. J. Adv. Res. 2 (2014) 633–638. [9] R.S. Meshram, Int. J. Innov. Eng. Technol. (IJIET) 4 (2014) 256–258. [10] R. Barir, B. Benhaoua, S. Benhamida, A. Rahal, T. Sahraoui, R. Gheriani, J. Nanomater. (2017) 1–10. [11] Z.T. Khodair, M.A. Al-Jubbori, A.M. Hassan, M.S. Aljuboori, F.I. Sharrad, J. Electron. Mater. 48 (2019) 669–678. [12] Z.T. Khodair, A.A. Khadom, H.A. Jasim, J. Mater. Res. Technol. 8 (2019) 424–435. [13] R.D. Shannon, Acta Cryst., A 32 (1976) 751–761. [14] A.M. Saleh, N.A. Bakr, Z.T. Khodair, Digest J. Nanomater. Biostruct. (DJNB) 13 (2018) 603–608. [15] I.M. Ali, A.M. Shano, N.A. Bakr, J. Mater. Sci.: Mater. Electron. (2018).
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Investigation on the structural and optical properties of copper doped NiO nanostructures thin films Ziad T. Khodair, Buthainah Abdulmunem Ibrahim ⇑, Mayada Kaream Hassan Department of Physics, College of Science, University of Diyala, Iraq
a r t i c l e
i n f o
Article history: Received 2 July 2019 Received in revised form 2 September 2019 Accepted 29 September 2019 Available online xxxx Keywords: NiO nanostructures Thin films Doping Optical properties Structural properties XRD AFM
a b s t r a c t In this research, copper is doped NiO nanostructures thin films by using various doping compositions (2, 4, 6 & 8%) have been prepared by chemical spray pyrolysis technique at a temperature of (400 °C). The optical, morphological and structural properties were investigated using UV–visible spectrophotometry, X-Ray diffraction (XRD) and atomic force microscopy (AFM). The results of (XRD) showed that all the prepared films are polycrystalline in nature with cubic structure with a strong (1 1 1) preferred orientation and the average crystallite size decreased with increase copper concentration, while the results of (AFM) indicate that the roughness of the surface decrease with increase doping. Enhancement of optical transmittance with doping decrease in the range (300–900 nm) was observed, and the absorption coefficient increased by increasing doping ratio, while the optical energy gap for allowing direct transmission decreased in the range (3.31 to 2.94 eV). Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Engineering & Science.
1. Introduction Nickel oxides is a transition metal oxide have main applications, such as sensors, smart window, electrodes for batteries [1]. NiO thin film can be produced by various techniques, which include, electrochemical, evaporation, spray pyrolysis and chemical techniques [2,3]. The use of nanomaterials is a new somehow area in the area of nanotechnology and nanoscience [4]. Nickel oxide is p-type semi-conducting with energy band gap (3.6–4 eV), and doped mineral oxide nanoparticles are salutary in a wide diversity of applications such as dilute magnetic semiconductors, photo detectors, optoelectronics [5,6]. Nickel oxide (NiO) is used in the manufacture of electric ceramics such as thermistors, and used as electrodes in optical and electronic devices and used in electrostatic sensor [7,8]. In this research, copper-doped NiO thin films was prepared, the structural, optical, and morphological properties were characterized using X-Ray diffraction, UV–visible spectrophotometry, and atomic force microscopy (AFM). 2. Experimental Copper-doped NiO nanostructures thin films (NiO:Cu) deposited on glass substrates using Nickel nitrate hex hydrate Ni (NO3)26H2O, ⇑ Corresponding author. E-mail address: [email protected] (B. Abdulmunem Ibrahim).
and copper nitrate trihydrate Cu (NO3) 23H2O. The deposition conditions of the all films were a between nozzle and substrate of 30 cm, interval spray of 2 min, spray time of 10 s and air pressure 1.3 bar. The (XRD) patterns were calculated from (a Shimadzu XRD-6000 company). The morphology of the films was characterized by Atomic force microscopy (AFM; SPM-AA3000) and (UV–Visible1800, Shimadzu). The thickness of the thin film is about (200 nm) calculated by using the following relation [9]:
t¼
DW qA
ð1Þ
Where, DW= (W2 W1), W1 denotes the weight of the substrate before the deposition and W2 denotes the weight of the substrate after deposition. A: The film area (cm2). q: density of film material (g/cm3). 3. Results and discussion 3.1. Structural properties The structural properties of (NiO: Cu) nanostructures thin films as shown in Fig. 1. The patterns of XRD are in good agreement with the ICDD card (04-0835), it is found that all the films were identified to be cubic structure with polycrystalline and the peaks diffraction are seen to be oriented at (1 1 1), (2 0 0) and (2 2 0)
https://doi.org/10.1016/j.matpr.2019.09.189 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Engineering & Science.
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
2
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 1. XRD patterns of NiO: Cu with various doping concentrations.
diffraction peaks. The preferred orientation doesn’t change when the copper-concentration increases. The lowest diffraction intensity peaks are found with an increase in the full width at half maximum (FWHM), that means the crystallization rate of the films decreases with the doping. The lack of crystallization rate can be explained by the type of chemical bond formed between the atoms
of the films material or by the specific heat of the solid body or by the difference of the melting points in the components of the material [10]. The average crystallite size (Dav) for (NiO: Cu) nanostructures thin films was calculated by the Scherrer relation for (1 1 1) preferred orientation and the relation [11,12].
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
3
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Structural parameters of NiO with various concentrations of Cu. Sample
2 H (deg)
d (Å)
hkl
NiO (ICCD) 04-0835
37.28 43.297 62.916
2.41 2.088 1.476
111 200 220
NiO-pure
37.1479 43.2166 62.8391
2.4183 2.0917 1.4776
NiO: Cu (2%)
37.14 43.1497 62.7284
NiO: Cu (4%)
FWHM (deg)
Dav (nm)
111 200 220
0.805
10.4
2.4188 2.0948 1.4799
111 200 220
0.52
10.41
37.1168 43.1252 62.684
2.4202 2.0959 1.4809
111 200 220
0.84
10
NiO: Cu (6%)
37.116 43.0564 62.6535
2.4203 2.0991 1.4815
111 200 220
1.01
8.3
NiO: Cu (8%)
37.11 43.056 62.5544
2.4206 2.0991 1.4836
111 200 220
0.97
8.6
Fig. 2. AFM images of (NiO: Cu) for doping concentrations a (0%) and b (2%).
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
4
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 3. AFM images of (NiO: Cu) for doping concentrations c (4%), d (6%) and e (8%).
Dav ¼
Kk bcosh
where: K: is shape factor depends on the shape of the material, b: The full width at half maximum (FWHM),
ð2Þ
k: Wavelength of X-ray, h: Bragg diffraction angle. The values of the average crystallite size are found to be within the range (10.4–8.3 nm), where the size decreases with increasing Cu doping concentration from (0% to 8%). copper and nickel have the same oxidation number of +2 but they marginally differ in ionic
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
radii because the ionic diameter of Cu+2 (0.73 Å) is very close to the ionic diameter of Ni+2 (0.69 Å) [13], which leads to the insertion of copper atoms as substitution atoms within the crystalline lattice. The values of (Dav) are found to be within in the nanoscale and structural parameters as shown in Table 1, so the (Dav) of the material plays an important role in determining the properties of the material.
Fig. 4, where transmittance decreases by increasing the rate of doping. This occurs due to the entry of copper atoms (Cu) which leads to additional levels formed at the bottom of the conduction band. The absorption coefficient of (NiO: Cu) nanostructures thin films was calculated by the following equation [12]:
a ¼ 2:303
3.2. Atomic force microscopy (AFM) AFM topography image of (NiO: Cu) nanostructures thin films provides information on droplet interaction with substrate glass and fairly agrees with the XRD results as shown in Figs. 2 and 3. The AFM images 2D and 3D indicated the formation of smaller grains with increasing Cu-substitution with distribution of granules on the surface of the films, also showed that NiO films are smooth and homogenous. The roughness surface values and Root Mean Square (RMS) decrease in range (12.6–1.85 nm) with the percentage of copper doping for all samples are shown in Table (2) and Table (3). 3.3. Optical properties The transmittance of (NiO: Cu) nanostructures thin films was calculated at the wavelength range (300–900 nm) as shown in
A t
ð3Þ
where: A: Absorption, t: thickness of the film (cm). The Fig. 5 shows (a) of all thin films as a function of wavelength. It depends on the energy of the photons and the semiconductor properties, which indicate that allowed electronic transitions are occurred due to the value of (a > 104 cm1). The optical energy gap for the electronic direct allowed transition of (NiO: Cu) nanostructures thin films are calculated by using relation (4), where the value of (r = 1/2). Fig. 6 shows the relation between (hma)2 and (hm). The value of the energy gap of the undoped NiO films is (3.33 eV), the energy gap decreases as increasing doping ratio as (3.31, 3.26, 3.15, 2.94 eV) at (2%, 4%, 6%, 8%) concentrations respectively. The reason is due to the formation of local levels close to the conduction band contributed to increase the electrons number of that reach the conduction band. This indicates that copper ions are compensated for the original matter ions in the crystalline structure of the NiO [14,15].
ahm ¼ Aðhm EgÞn
Table 2 Surface roughness and RMS for Cu-doped NiO.
5
ð4Þ
where,
Sample
Surface roughness (nm)
RMS (nm)
NiO-pure NiO: Cu (2%) NiO: Cu (4%) NiO: Cu (6%) NiO: Cu (8%)
11.1 0.37 1.02 1.08 1.63
12.6 0.43 1.18 1.3 1.85
Table 3 Energy gaps for allowed transition.
direct
Sample
Eg (eV)
NiO-pure Ni: Cu (2%) Ni: Cu (4%) Ni: Cu (6%) Ni: Cu (8%)
3.33 3.31 3.26 3.15 2.94
Fig. 4. The transmittance spectra for Cu-doped NiO.
(Eg): The energy gap, A: the constant depending on the structure of the material, while the exponent (r) depends on the type of transition. 4. Conclusions In summary, we have firstly prepared (NiO: Cu) nanostructures thin films by using various doping compositions (2, 4, 6 & 8%). The effect of copper doping on crystallinity, morphological and optical properties was investigated. XRD patterns indicate that all films are cubic structure with polycrystalline and preferred orientation at (1 1 1), which doesn’t change when the copper doping increases. the average crystallite size decreases with increasing Cu doping concentration from (0% to 8%). The AFM results showed that the roughness surface values and (RMS) decrease with increase of the percentage of copper doping. The optical energy band gap
Fig. 5. The absorption coefficient for Cu-doped NiO.
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189
6
Z.T. Khodair et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 6. Optical energy gap for NiO for Cu-doped NiO.
and transmittance values were found to decrease. The absorption coefficient (a) of the copper doped NiO at different copper doping levels has (a > 104 cm1) which indicates the increase of the probability of the occurrence of direct allowed transition. References [1] [2] [3] [4]
S. Sagadevana, S. Rajeshb, I. Dasc, Mater. Today:. Proc. 4 (2017) 4123–4129. S.A. Mahmoud, A.A. Akl, H. Kamal, K. Abdel-Hady, Phys. B 311 (2002) 366. J.K. Kang, S.W. Rhee, Thin Solid Films 391 (2001) 57. A.H. Abed, Z.T. Khodair, T.M. Al-Saadi, T.A. Al-Dhahir, AIP Conf. Proc. 2123 (2019) 020019. [5] Z.T. Khodair, A.A. Kamil, Y.K. Abdalaah, Physica B 503 (2016) 55–63.
[6] A.H. Abed, T.M. Al-Saadi, Z.T. Khodair, ARPN J. Eng. Appl. Sci. 13 (2018) 8049– 8054. [7] D. Franta, B. Negulescu, Thomas, P.R. Dahoo, M. Guyot, I. Ohlídal, J. Yamaguchi, T. Mistrík, Appl. Surf. Sci. 244 (2005) 426–430. [8] S.S. Ahmed, E.K. Hassan, G.H. Mohamed, Int. J. Adv. Res. 2 (2014) 633–638. [9] R.S. Meshram, Int. J. Innov. Eng. Technol. (IJIET) 4 (2014) 256–258. [10] R. Barir, B. Benhaoua, S. Benhamida, A. Rahal, T. Sahraoui, R. Gheriani, J. Nanomater. (2017) 1–10. [11] Z.T. Khodair, M.A. Al-Jubbori, A.M. Hassan, M.S. Aljuboori, F.I. Sharrad, J. Electron. Mater. 48 (2019) 669–678. [12] Z.T. Khodair, A.A. Khadom, H.A. Jasim, J. Mater. Res. Technol. 8 (2019) 424–435. [13] R.D. Shannon, Acta Cryst., A 32 (1976) 751–761. [14] A.M. Saleh, N.A. Bakr, Z.T. Khodair, Digest J. Nanomater. Biostruct. (DJNB) 13 (2018) 603–608. [15] I.M. Ali, A.M. Shano, N.A. Bakr, J. Mater. Sci.: Mater. Electron. (2018).
Please cite this article as: Z. T. Khodair, B. Abdulmunem Ibrahim and M. Kaream Hassan, Investigation on the structural and optical properties of copper doped NiO nanostructures thin films, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.189