Ternary thin films of Iron Copper Sulphide (FeCuS) have been grown and characterized. Optical, compositional, surface microstructure and structural characterization of the deposited films were carried out. Absorbance spectra data of the films were obtained using a Janway 6405 UV-VIS spectrophotometer, absorbance of the films were found to be high in UV and low in VIS – NIR region, while the transmittances were low in UV region and high in VIS – NIR regions. Elemental composition of the films were done using Skyray XRF Machine, EDX Pocket III, model P530. The machine was used to determine the percentage of each transition element present in the films. The surface microstructures of the films were characterized using Olympus Microscope at 100X magnification.  XRD analysis of the films was carried out using Enhance Mini Material Analyzer (EMMA) X – Ray Diffractometer Machine, the as - deposited FeCuS thin film was found to have tetragonal structure. The lattice constants obtained are  ,   and  . The crystallite size of the film was calculated at   wavelength of   and the calculated grain size was found to be  . The optical absorption study reveals that FeCuS thin film has a bandgap of 2.40eV and a refractive index range of   to   at 400nm. The reflectance of the deposited films was found to be generally low

I. A., Ezenwa

N. L, Okoli .

International Journal of Innovative Technology and Research (IJITR)

   Ezenwa I.A* et al.   (I JITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH  Volume No.3 , Issue No.4, June - July 2015, 2202 - 2206. 2320 –5547  @ 2013 http://www.ijitr.com All rights Reserved.   Page | 2202 Optical and Structural Characterization of FeCuS Ternary Thin Films EZENWA I. A. Anambra State University Uli, Anambra State, Nigeria  OKOLI N. L. Anambra State University Uli, Anambra State, Nigeria  Abstract : Ternary thin films of Iron Copper Sulphide (FeCuS) have been grown and characterized. Optical, compositional, surface microstructure and structural characterization of the deposited films were carried out. Absorbance spectra data of the films were obtained using a Janway 6405 UV -VIS  spectrophotometer, absorbance of the films were found to be high in UV and low in VIS – NIR region, while the transmittances were low in UV region and high in VIS – NIR regions. Elemental composition of the films were done using Skyray XRF Machine, EDX Pocket III, model P530. The machine was used to determine the percentage of each transition element present in the films. The surface microstructures of the films were characterized using Olympus Microscope at 100X magnification.  XRD analysis of the films was carried out using Enhance Mini Material Analyzer (EMMA) X – Ray Diffractometer Machine, the as - deposited FeCuS thin film was found to have tetragonal structure. The lattice constants obtained are           ,            and           . The crystallite size of the film was calculated at      wavelength of          and the calculated grain size was found to be                     . The optical abs orption study reveals that FeCuS thin film has a bandgap of 2.40eV and a refractive index range of       to       at 400nm. The reflectance of the deposited films was found to be generally low.  Keywords: Iron copper sulphide; Chemical Bath Deposition; Optical characterization; compositional  characterization; Structural characterization.  I. INTRODUCTION Ternary thin films are thin films that contain three different elements. The preparation and study of physical properties of ternary chalcogenide compounds have increased in recent years [1]. Ternary compounds are found to be suitable material for optoelectronic device applications and good material for window layer solar cells [2]. Some of the films are investigated for use as super-ionic conducting materials [3]. Ternary compounds had also been studied for efficient solar energy conversion materials [4]. Ternary thin film have been grown and characterized by some researchers for specific applicat ions in solar industries, optoelectronics devices and window coating, examples include, CuInS2 [5], [6], [7], CuSbS2  [8], FeCuS2 [9], Cu2SnS3 [10], PbCdS [11], CuNiS [2], CdS/CuS and CuS/CdS [13]. FeCuS2 fabricated by [9], have a band gap energy of 2.4 eV to 2.8 eV and indirect band gap energy of 0.6 eV to 1.0 eV.  In this paper, FeCuS thin films were deposited using chemical bath method, time as a bath parameter was optimized. Optical and Structural Characterizat ion of the deposited thin films were investigated. The optical properties investigated include; absorbance (A), transmittance (T) and reflectance (R), which were used to calculate other parameters such as refractive index (n), ext inction coefficient (K) and the band gap energy of the as – grown films.   II. MATERIALS AND METHOD The growth of FeCuS thin films on glass slides was carried out using chemical bath deposition technique. The glass slides used were previously  inserted in trioxonitrate (V) acid for 48 hours, washed with detergent, rinsed in distilled water and dried in air. The degreased cleaned surface provide nucleation center for the growth of the films onto the substrate surface hence will result to highly adhesive and uniformly deposited films  on the surface of the substrate. The slides for the deposition of FeCuS were labelled                        . Iron Copper sulphide (FeCuS) was deposited by the reaction of solution containing iron (III) trioxonitrate nanohydrate [Fe(NO3)3.9H2O], copper chloride dihydrate [CuCl.2H2O], disodium ethylenediaminetetraacetate [Na4(C10H16N2O8)] commonly known as EDTA, triethanolamine [C6H15NO3] also known as TEA, ammonium solution [NH4OH], thiourea (NH2)2CS and distilled water in a 100 ml beaker. The complexing agents used in this research are EDTA and TEA. The addition of  TEA and EDTA as complexing agents slowed down the precipitation of metal ions of iron and copper. Ammonia solution stabilizes or adjusts the pH of the mixture.  Five reaction baths containing slides                         were used, average room temperature of 303 K was maintained.     of Iron (III) trioxonitrate nanohydrate and Copper chloride dehydrate were measured and transferred    Ezenwa I.A* et al.   (I JITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH  Volume No.3 , Issue No.4, June - July 2015, 2202 - 2206. 2320 –5547  @ 2013 http://www.ijitr.com All rights Reserved.   Page | 2203 into the beaker. The mixture was stirred after which     of thiourea was added and stirred to have a homogeneous mixture. Addition of thiourea formed a sky blue jelly – like solution. Followed by addition of       of EDTA,       of TEA and     of ammonium solution. The solution was stirred for 5 minutes followed  by addition of      of distilled water. The final solution was stirred to have a homogeneous mixture. The five beakers with slide                         were prepared in the same manner. The varying bath parameter is the deposition time.     was allowed  to stand in the bath for 12 hours after which deposition was noticed on the films. The remaining substrates,                    were allowed for 24 hours, 36 hours, 48 hours and 60 hours respectively. The substrates were removed at the end of each time, rinsed in distilled water, and dried in open air at room temperature of (300K). The peak deposition time was at 48 hours. At 48 hours, a uniform and adherent film was noticed on substrates. An average pH of 8.3 was obtained for the bath using a pH meter o f accuracy     . Table 1 shows the constituents of the bath parameters.  Table 1: Optimization of Iron Copper Sulphide (FeCuS) Deposition with Time at Room Temperature  The stepwise reactions involved in the complex ion formation and film deposition processes for FeCuS are stated below. Sulphide ions are released by the hydrolysis of thiourea and Fe3+and Cu2+ were released from the complex ion formed by the reaction of iron and copper compounds with EDTA and TEA respectively.                                                                                                                                                                                                                        After the deposition of the films, optical, compositional, surface microstructure and structural characterization of the deposited films were carried out. Absorbance spectra data of the films were obtained using a Janway 6405 UV-VIS spectrophotometer. Elemental composition of the films were done using Skyray XRF Machine, EDX Pocket III, model P530. The machine was used to determine the percentage of each transition element present in the films. The surface microstructures of the films were characterized using Optical Microscopy, Olympus Microscope at 100X magnificat ion was used to examine and produce micrographs of the grown thin film samples. XRD analysis of the films was carried out using Enhance Mini Material Analyzer (EMMA) X – Ray Diffractometer Machine. Th is is to determine the crystalline nature of the films, 2 theta angles, d - spacing and to calculate the grain size.  III. RES ULTS AND DISCUSS ION Thicknesses of the films    ,    ,    ,     and     at        were plotted against time of deposition of       ,       ,       ,        and        as shown in Figure 1.     has a peak thickness value of         at this wavelength. The thickness increases from         at        to         at        before decreasing to         at        and remains constant at         and       .  Fig. 1:Variation of Thickness (μm) versus Time (hrs) for Slides   ,    ,    ,     and    Reaction bath Dip time (hr) Fe(NO3)3.9H2O CuCl.2H2O EDTA TEA  H2O Vol. (ml) (NH2)2CS NH4OH Mol. (m) Vol. (ml) Mol. (m) Vol. (ml) Mol. (m) Vol. (ml) Mol. (m) Vol. (ml) Mol. (m) Vol. (ml) Mol. (m) Vol. (ml) FC1 12 2.00 3.00 2.00 3.00 0.50 1.00 7.40 1.00 35.00 2.00 2.00 14.00 3.00 FC 2 24 2.00 3.00 2.00 3.00 0.50 1.00 7.40 1.00 35.00 2.00 2.00 14.00 3.00 FC 3 36 2.00 3.00 2.00 3.00 0.50 1.00 7.40 1.00 35.00 2.00 2.00 14.00 3.00 FC 4 48 2.00 3.00 2.00 3.00 0.50 1.00 7.40 1.00 35.00 2.00 2.00 14.00 3.00 FC 5 60 2.00 3.00 2.00 3.00 0.50 1.00 7.40 1.00 35.00 2.00 2.00 14.00 3.00    Ezenwa I.A* et al.   (I JITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH  Volume No.3 , Issue No.4, June - July 2015, 2202 - 2206. 2320 –5547  @ 2013 http://www.ijitr.com All rights Reserved.   Page | 2204  Fig. 2: Graph of Abs orbance (abr. Unit) versus wavelength (nm)for Slides    ,    ,    ,     and     Absorbance of as – grown films were plotted against wavelength as shown in Figure 2.     has the least absorbance value followed by    ,    ,     and    . Absorbance decreases as time of deposition increases except fo r    that has least absorbance values among all samples. Generally, absorbance of the films decreases as the wavelength increases and is high in UV reg ion but has low values in VIS and NIR regions.  Fig 3.: Fig.3:Graph of percentage Transmittance (% ) versus wavelength (nm) for Slides    ,    ,    ,     and     Transmittance as a function of wavelength is plotted in Figure 3, for    ,    ,    ,     and     respectively. Transmittance of the films increases as the wavelength increases and it increases as the time of deposition increases except for     that has highest values in all wavelength regions considered.     has transmittance values of     at        and increases to     at       . In VIS region, it increases from     to     at       , before getting to     at         in NIR region.   Fig 4: Graph of reflectance versus wavelength (nm) for slide    ,    ,     and     Reflectance of as – grown films for     ,    ,     and     were p lotted against wavelength as shown in Figure 4. From the graph, the reflectance of the as grown thin films is very low. The grown thin films have a peak value of approximately      at different wavelengths. It remains approximately the same throughout the VIS region. Due to their low reflectance, they could be used as anti – reflective coatings materials.  Figure 5, shows the graph of refractive index of the films    ,     and     against wavelength. The refract ive index of the films was studied within the VIS and NIR regions of electromagnetic spectrum.  From the graph, it can be seen that the refractive index of the films decreases slightly as wavelength increases.   Fig 5: Graph of Refractive Index Versus Wavelength(nm) for Slide    ,     and     Refractive index range of      to       at 400nm is observed in the deposited films. These films are high refractive index materials. These high values of refractive index suggest that they could be used as anti – reflective coating and photonic devices such as light emitting diodes (LEDs), image sensors etc. [14].    Ezenwa I.A* et al.   (I JITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH  Volume No.3 , Issue No.4, June - July 2015, 2202 - 2206. 2320 –5547  @ 2013 http://www.ijitr.com All rights Reserved.   Page | 2205  Fig. 6: Graph of Extinction Coefficient K versus wavelength (nm) for Slides     ,    ,    ,     and     Extinction coefficient of films    ,    ,    ,     and     were plotted against wavelength in Figure 6 as shown above. All the graphs show the same pattern. The Ext inction coefficient decreases as wavelength increases.     has extinction coefficient values of           - to           at        -       ,.     has extinction  coefficient values of           to           in UV reg ion,           to           in VIS region and           to           in NIR region.  Fig 7.: Graph of Optical Conductivity versus wavelength (nm) for Slides   ,    ,     and     Optical conductivities of slides    ,    ,     and     films were p lotted against wavelength in Figure 7.     has optical conductivity values of               at        to              at        and              at        .  Figure 8 is a plot of absorption coefficient squared (2) versus photon energy h for       thin film. The optical bandgap energy of       thin films were determined from this graph by extrapolating the straight portion of the graph to 2=0. Our result shows that                     has band gap energy of        .This result is in agreement with results obtained by [9] and  [13]. Due to the wide band gap of the as – grown films, they could be considered as material for absorber layer of solar cell and as effective coating material fo r poultry houses [13].  Fig.8: Graph of (αhυ)2versus Photon Energy (eV) for F   Figure 9 and 10 shows the micrograph of FeCuS thin films for slides    ,    . Critical observations of the micrographs reveal that the films are crystalline in nature and have small grain sizes. The particle grain sizes increased as the time of deposition of the reaction bath increases.  Fig. 9: Micrograph of       for     Thin Film  Fig. 10: Micrograph of       for     Thin Film Figure 11 shows the X – ray diffraction spectra of chemically deposited FeCuS thin film. According to the result, the deposited thin film is crystalline with chemical formular           which has a tetragonal structure and the mineral name is Mooihoekite (JCPDS card number 01 – 071 – 0527). The lattice constants are           ,            and           . The crystallite size o f the film was calcu lated at       wavelength of          and the grain size was calculated using Scherrer’s formula. The calculated grain size was found to be                     . Table 2: XRD Analysis of Chemically Deposited FeCuS Standard Peak Calculated Peak  2θ ( ) d – Spacing ( ) 2θ ( ) d – Spacing ( ) (hkl) 23.554 3.774 23.300 3.815 201     Ezenwa I.A* et al.   (I JITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH  Volume No.3 , Issue No.4, June - July 2015, 2202 - 2206. 2320 –5547  @ 2013 http://www.ijitr.com All rights Reserved.   Page | 2206  Degrees 2 - Theta Fig. 11: XRD pattern of FeCuS Thin Film Table 3: Elemental Analysis of as – grown Thin Films SAMPLE  Ti (%)  Cr (%)  Fe(%)  Cu (%)  Zn (%)  Pb (%)  FC5  0.0654  0.0891  80.9295  18.5298  0  0.04416  Elemental components of characterized films are shown in table 3. From the table, it can be seen that for sample   , iron content is         , copper content is         . Other elements amount to         . IV. CONCLUS ION In summary, XRD result shows that we have successfully fabricated Ternary thin films of Iron Copper Sulphide ( FeCuS) deposited on glass substrates through chemical bath technique. Absorbance of the films were found to be high in UV and low in VIS – NIR region, while the transmittances were low in UV reg ion and high in VIS – NIR regions. Elemental components of the characterized films for sample     was found to be: iron content (         , copper content           ), other elements amount to         . The as - deposited FeCuS thin film has tetragonal structure. The lattice constants are           ,            and           . The Calculated grain size was found to be                     . The optical absorption study reveals that FeCuS thin film has a bandgap of 2.40eV and a refractive index range of  of      to       at 400nm. The reflectance of the deposited films was found to be generally low.  V. REFERENCES  [1]  Nair P. K. and Nair M. T. S.,  ''Chemically  Deposited ZnS Thin Film: Applicat ion as Substrate for Chemically Deposited B2S3, CuxS and PbS Thin Films '', Semiconductor Science Technology Vol.7 p. 239, 1992. [2]  Woon-Jo J. and Cye-Choon P., ''Structural and Electrical Propert ies of CuGaS2 Th in Films by Electron Beam Evaporation'', Solar Energy Material and Solar Cells Vol. 75 pp. 93 – 100, 2003. [3]  Nair P. K., Ocampo M., Fermandez A. and Nair M. T. S., ''Solar Control Characterizat ion of chemically Deposited Lead Sulphide coatings'', So lar Energy Material, Vol. 20, issues 3, pp. 235 – 243, 1990. [4]  Lee Jae-Hyeong, Song Woo-Chang, Yi Jun-Sin and Yoo Yeong-Sik,  ''Characteristics of the CdZnS Thin Films Doped by Thermal Diffusion of Vacuum Evaporated Indium Films'', Materials and Solar Cells Vol. 75, issues (1-2), pp. 227 – 234, 2003. [5]  Ingrid R., Miguel A.C., Brain E., Clay D. H., John S., Craig L.P., Bobby T. and Romenel N., ''19.9% efficient ZnO/CdS/CuInGaSe2 solar cellwith 8.1% Fill Factor'', Progress in Photovoltaics, Research and Application, pp. 235 – 239, 2006.  [6]  Emst K., Belaidi A. and Konenkamp R., ''So lar Cell with Extreme Thin Absorber on Highly Structured Subtrate'', Semiconductor Science Technology, 18,pp. 475 – 479, 2003. [7]  Muffer H.J., Fischer C.H., Diesner K. and Lux S. M., ''ILGAR – A Novel Thin Film Technology for Sulphides '', Solar Energy Material and Solar Cells , Vol. 67,pp. 121 - 127, 2001. [8]  Ezugwu S. C., Ezema F. I. and Asogwa P. U., ''Synthesis and Characterization of Ternary  CuSbS2 Thin Films: Effect of Deposition Time'', Chalcogenide Letters , Vol. 7, No. 5, pp. 341 – 348, 2010. [9]  Uhuegbu, C. C., ''So lution Growth Technique for FeCuS2 Ternary Thin Film and its Optical Characteristics '', American Journal Scientific and Industrial Research, Vol. 1(3),pp. 392 – 396, 2010. [10]  Berg D.M.,  Rabie D., Levent G., Guillaume Z., Susanne S. and Phillip J. D., ''Th in Film Solar Cells Based on the Ternary Compound Cu2SnS3, Thin Solid Films'', Vol. 520, 6291–6294, 2012. [11]  Mohammed M. A., Mousa A.M., and Ponpon J. P., ''Optical and Optoelectric Propert ies of PbCdS Ternary Thin Films Deposited by CBD'', Journal of Semiconductor Technology and Science, Vol.9, No.2. pp. 111 – 117, 2009. [12]  Ottih I. E., Ekpunobi A. J and Ekwo P.I., ''So lid State and Optical Properties of Chemical  Bath Deposited Copper Nickel Sulphide (CuNiS) Thin Films '', The Pacific Journal of  Science and Technology'', Volume 12, No. 2, pp. 342 – 347, (2011). [13]  Ezema F. I. and Nnabuchi M. N., ''Growth Characteristic and Effect of Thickness on Optical Properties of Iron Copper Sulphide (FeS2 / CuS3) Thin Films'', Journal of Applied  Science and Technology, Vol. 10, N0.1, pp. 53 – 59, 2005. [14]  Jin – gang L. and Mitsuru U., ''High Refractive Index Polymer: Fundamental and Practical Applications '', Journal of Material Chemistry, Vol. 19, pp. 8907 – 8919,(2009. 

OPTICAL AND STRUCTURAL CHARACTERIZATION OF FECUS TERNARY THIN FILMS

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OPTICAL AND STRUCTURAL CHARACTERIZATION OF FECUS TERNARY THIN FILMS

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International Journal of Innovative Technology and Research (IJITR)