IJPRD, 2014; Vol 6(12):January-2015(05 - 07) International Standard Serial Number 0974 – 9446 -------------------------------------------------------------------------------------------------------------------------------------------------STRUCTURAL AND MORPHOLOGICAL PROPERTIES 0F INDIUM SELENIDE THIN FILMS DEPOSITED BY CHEMICAL BATH DEPOSITION Sanjay B. Bansode *1 and Vasant G. Wagh2 1* Advanced Physics Laboratory, Department of Physics, University of Pune, Pune- 411 007 2 K.V.N.Naik College of Arts Science and Commerce, Nashik, MH, India *College affiliated to Savitribai Phule Pune University. Pune.(Maharashtra) ABSTRACT Indium selenide films were deposited using chemical bath deposition. The films were deposited on FTO coated glass substrate by using In2(SO4)3 as indium source and selenium powder as selenium source. The films were characterized using the different techniques with respect to their crystal structure, optical and electrical properties by means of X-ray diffraction, scanning electron microscopy. X-ray diffraction studies revealed that amorphous nature of the deposited films. The scanning electron microscopy picture of as deposited indium selenide film layer shows leaf like structure over the surface of the substrate. Optical absorption study shows that InSe is a direct band gap material with band gap 1.54 eV. Correspondence Author Sanjay B. Bansode, Advanced Physics Laboratory, Department of Physics, University of Pune, Pune- 411 007 Keywords- Indium selenide; Chemical bath deposition; thin films etc. INTRODUCTION Indium selenide is important material for optoelectronic and photovoltaic application due to its stability and wider band gap. It can be used as effective nontoxic substitute for cadmium sulfide CdS in Cu(InGa)Se2 based on solar cell. Indium selenide belongs to group III-VI compound material. Indium selenide could be prepared using different method such as chemical vapor deposition [1], Spry pyrolysis[2] chemical bath deposition[3],evaporation technique[4]. Of this, chemical bath deposition is simple method which can be used for deposition of large area thin films. In present work indium selenide thin films were deposited by chemical bath deposition, using triethanolamine [TEA] and Hydrazine hydrate (HH) Available online on www.ijprd.com 5 International Journal of Pharmaceutical Research & Development complexed with indium sulphate. The aim of this work is to study the structural, optical, surface morphological properties of indium selenide thin films using X-ray diffraction, scanning electron microscopy (SEM), electron dispersive Spectroscopy, optical absorption. EXPERIMENTAL DETAILS Indium selenide films were deposited by chemical bath deposition. The deposition was carried out on FTO coated glass substrate by sequential addition of indium sulphate, 80 % Hydrazine hydrate, triethanolamine, these solution used as received. Deposition of InSe was carried out in alkaline bath. The solution prepared in 30 ml beaker by sequential addition of 5ml of 0.1M indium sulphate, 0.1 ml of 0.15M triethanolamine. Solution was stirred well, under the continuous stirring condition 0.1 ml of hydrazine hydrate was mixed and 5 ml of 0.1M Na2se(so3) solution was added to the bath. The initial pH of the solution was about 9. Clean and FTO coated glass substrate were placed vertically in reactive solution at room temperature. Films were deposited about 72 hours. The resulting indium selenide films were brownish in color and very well adherent. Microstructures of the films were studied using scanning electron microscope (SEM) for the different magnifications. The optical absorption measurements in the range of 350 - 900 nm were carried, XRD patterns were obtained by using X-ray diffractometer (XRD Rigaku D/max-2400 with Cu-kα= 0.154nm). RESULT AND DISCUSSION The structural identification of indium selenide thin films was studied with X-ray diffraction techniques. The XRD was carried out in the range of diffraction angle of 2θ between 20 and 80. From X-Ray pattern (Not shown Fig.), It is clear that indium selenide films are amorphous in nature. ISSN: 0974 – 9446 However T Fujiwara et al [5] reported that the growth of In2Se3 phase may be attributed to amorphous and polycrystalline nature of substrate. The composition of as deposited films was determined from energy dispersive X-ray analysis. SEM image of InSe deposited on FTO coated glass substrates are shown in Figure 1. The surface shows random distribution leaf like dense structure. Film covers the entire substrate surface which accounts for the high mechanical stability of deposited films. The atoms deposited on glass substrate cannot move freely due to insufficient thermal energy provided to the substrate at room temperature (fig b), therefore films deposited at low temperature exhibited poor crystallinity. (a) (b) (c) FIGURE 1. SEM images of InSe thin film deposited at on to FTO coated glass substrate at (a) 3000X and (b) 10000X and (c) 30000X Available online on www.ijprd.com 6 International Journal of Pharmaceutical Research & Development It has been reported that optical band gap of indium selenide varied from 1.2 to 2.0 eV with several phases [6]. To determine the optical band gap of as deposited indium sulfide thin film Figure 2 shows the plot of (αhυ)2 versus (hυ) for the deposited thin film. The band gap of 1.54 eV was estimated by extra plotting the straight line part of the plot to energy axis ISSN: 0974 – 9446 CONCLUSION In this paper, structural, and morphological properties of chemically deposited InSe thin films were reported. XRD studies showed the amorphous nature of InSe thin films. SEM shows random distribution of leaf like structure with irregular shape. From optical studies gap was found to be 1.54 eV. Angle of contact confirms high surface energy of deposited thin film. 0 .9 0 .8 REFERENCES 1. J.W. Cheon, J. Arnold, K.M. Yu, E.D. Bourret, Chem. Matter. 7 (1995), 2273. 2. H.BouZouita, N. Bougulia, S. Dachemin, S. Fiechetr, A.Dhouib, Renew. Energy 25, (2002), 131. 3. K. Bindu, M. Lakshmi, S. Bini, C. Sudha Kartha, K.P. VijYakumar, T.Abe, Y. Kashiwada, in; proceding of the national symposium on science and tech. of vaccum and Thin films (IVSVS-2001), 33 PP. 4. C.H. de Groot, J. S. Moodera, J. Appl. Phys. 89 (2001) 4336 5. T. Fujieara, Y. lgasaki, Journal of Crystal growth. 178 (1997) 332-334 6. C. Gullien, A Chery, D. Saipkas, phys. Stat. Sol. (a) 118 (1990) 553 0 .7 (absorbance) 2 0 .6 0 .5 0 .4 0 .3 0 .2 0 .1 0 .0 1 .0 1 .5 2 .0 2 .5 3 .0 E n e rg y (e V ) Figure.2 plot of (absorbance) 2 against Energy (hυ) for as deposited InSe thin film Angle of contact Angle of contact of as deposited films were measured by using travelling microscope. Angle of contact is lees than 90o which indicate high surface energy shown in Figure 3. It shows that resistivity decreases with increase in temperature this confirm semiconducting nature. Figure.3 angle of contact ***** Available online on www.ijprd.com 7
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