International Review of

Physics (IREPHY)

Contents Detection of Absolute Rest Frame by Measuring Light Wavelength of Light Source in Uniform Rectilinear Motion by Justin C. H. Lee

Determination of Microstructure and Mechanical Behaviour of SiC Particle Reinforced Aluminum Matrix Ceramic Composites by Dunia K. M. Al-Nasrawy

Zinc Oxide Thin Films Prepared by Atmospheric Pressure Chemical Vapor Deposition Using Zinc Chloride by S. Maifi, M. S. Belkaid, R. Zirmi, L. Escoubas, M. Pasquinelli

A New Analytical Solution to the Relativistic Polytropic Fluid Spheres by M. I. Nouh, A. S. Saad

Texture Coefficient and Conductivity Dependence on the Annealing and Thicknesses of Thin CdS Films by Eman M. Nasir

A Study of Some Environmental Effects for Saw Dust Wood / Phenol–Formaldehyde Composites by Harith I. Jaafer , Zainab R. Muslem, Iqbal S. Naji

Microscopic Study of Anode and Cathode Corona in Argon Colliders by R. A. El-Koramy, A. M. A. Amry, A. S. Gabre

Polarized Infrared Reflectance Studies for Wurtzite Al0.06Ga0.94N Epilayer on Sapphire Grown by MBE by A. I. Aljameel, H. Abu Hassan, S. S. Ng

A Low Temperature Atmospheric Pressure Plasma Jet by Hammad R. Humud, Ahamed S. Wasfi, Wafaa Abd Al-Razaq

Correlation between Microscopic and Macroscopic Conductivity Models through Meyer-Neldel Rule by F. Abdel-Wahab, E. M. Ahmed

The Nonlinear Dose Response of OTOR-Model Thermoluminescence Glow Peaks in Case of Temperature-Dependent Frequency Factor by M. S. Rasheedy, Gh. S. M. Hassan, E. M. Zahran, A. I. Abd-Elmageed

Flash Evaporation of CdS Thin Film by Raad M. S. Al-Haddad, Salah Abdulla Hasoon, Shurooq S. Mahmood, Issam M. Ibrahim

Characterization of Argon Plasma Induced by Simple 2.45 GHz Microwave Source

by Ahmed S. Wasfi, Hamad R. Humud, Ali H. Muhammad, Mazin S. Al-Ansari

Electrical Properties of Thermally Evaporated CdSexS1-x Thin Films by Nada K. Abbas, Iqbal S. Naji , Alaa A. Abdulmajeed

Nanostructural ZnO:Al On Porous Silicon Gas Sensor by Raad S. Sabry, Dhaidan kh. Kafi

Effect of Secondary Electron Emission on Argon Glow Discharge Characteristics

by F. Bouanaka, S. Rebiai

Effect of Magnetic Field and Porosity on Peristaltic Flow of Micropolar Fluid

by A. M. Abd-Allaa, G. A. Yahya, A. M. Farhan

X- Ray Mass Attenuation Coefficients of Some 3d Elements Compounds at Am-241(40mCi) by Farid M. Mohammed, Raed N. Razooqi, Muataz A. Majeed, Y. K. Vijay, Subodh Sirvastava

Reverse I-V Behaviour of SiC Schottky Diodes under Various Temperatures and Magnetic Fields by D. Chalabi, Z. Chalabi, A. Saidane, S. Mimouni, M. Ketata

Growth and Structure of Silver Oxide Thin Films Using Rapid Thermal Oxidation Method

by Ibrahim R. Agool, Marwa Abdul Muhsien, Lamyaa M. Raoof

The Effect of Gamma Radiation on the Optical Properties of (PC-PS) Polymer Blend

by S. M. Hassan, N. M. Hassan, A. F. Sultan, Q. G. Al-Zaidi

Heat and Mass Transfer for a Maxwell Fluid Flow Near a Stagnation Point with Variable Wall Heat and Mass Flux in the Presence of Heat Generation or Absorption by Mostafa A. A. Mahmoud, Shimaa E. Waheed

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February 31, 2013

International Review of

Physics

(IREPHY)

Managing Editor:

Santolo Meo

Department of Electrical Engineering

Federico II University

21 Claudio – I80125 Naples, Italy

santono@unia.it

Editorial Board:

Vladimir M. Agranovich (U.S.A) University Of Texas at Dallas – Nano Tech Institute

Anastasios Anstaslaids (GREECE) National Observatory of Athens - Institute for Space Applications & Remote Sensing Jean-Pierre Badiali (FRANCE) Université Pierre et Marie Curie – Directeur de recherche CNRS

Marcia C. Barbosa (BRASIL) Universidade Federal do Rio Grande do Sul - Instituto de Fisica

Israel Felner (ISRAEL) The Hebrew University - Racah Institute of Physics Peter Hanggi (GERMANY) University of Augsburg - Institute of Physics

Hans Herrmann (BRASIL) Universidade Federal do Ceará - Departamento de Física

Joshua Jortner (ISRAEL) Tel Aviv University – School of Chemistry Vladimir G. Kadyshevsky (RUSSIA) Joint Institute for Nuclear Research

Yuri Kozitsky (POLAND) Maria Curie-Sklodowska University, Lublin

Bo Lehnert (SWEDEN) Royal Institute of Technology- School of Electrical Engineering -Fusion Plasma Physics Jukka Maalampi (FINLAND) University of Jyväskylä - Department of Physics

Tito Mendonca (PORTUGAL) IPFN, Instituto Superior Técnico

Risto M. Nieminen (FINLAND) Helsinki University of Technology - Department of Engineering Physics Dorin Poenaru (ROMANIA) H. H. National Institute of Physics & Nuclear Engineering

Rajeev Kumar Puri (INDIA) Panjab University

Kestutis Pyragas (LITHUANIA) Semiconductor Physics Institute Antoni Roglaski (POLAND) Military University of Technology - Institute of Applied Physics

Padma K. Shukla (GERMANY) Universitaet Bochum - Fakultaet fuer Physik und Astronomie

Gowind Swarup (INDIA) Tata Institute of Fundamental Research - National Centre for Radio Astrophysics - Hugo Thienpont (BELGIUM) Vrije Universiteit Brussel - Department of Applied Physics and Photonics

Sergey Vladimirov (AUSTRALIA) University of Sydney - School of Physics

Christian Von Ferber (U.K.) Coventry University - Applied Mathematics Research Centre

Miki Wadati (JAPAN) University of Tokyo - Department of Physics

Xin-Nian Wang (U.S.A) Lawrence Berkeley National Laboratory - Nuclear Science Division

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3

Texture coefficient and Conductivity Dependence on the Annealing

and Thicknesses of Thin CdS Films

Eman M. Nasir Thin Film Labrotary, Department of physics, College of Sciences, University of Baghdad

Aljadriah, Baghdad, Iraq

Corresponding Author: emnasir_7@yahoo.com

Abstract- Cadmium sulfide thin films prepared by thermal evaporation technique with substrate

temperature of 333 K, the film deposited with different thicknesses (100, 150, 200 and 250 nm), then

annealed at 373, 423 and 473 K. X-ray diffraction spectra of CdS films were hexagonal polycrystalline

structure. The texture coefficient has determined, the highest value of it has observed for the thicker film.

The electrical conductivity display two stages of conductivity through the heating temperature range for

all thicknesses. Conductivities of the films were found to increase with increasing the annealing

temperatures and the thicknesses. Also it can be observed that the conductivity of the film of 250 nm is

higher than other films. The thermal activation energies for as deposited CdS and annealed thin films

increased with increasing the annealing temperature at the lower temperature range, while they

decrease with increasing the thicknesses. Copy right © 2013 Praise Worthy Prize S.r.l. –All right

received

Key World: Thin CdS film, Thermal evaporation, X- ray Diffraction, Electrical Conductivity.

I. Introduction

Cadmium sulfide (CdS) is one of the cheapest

semiconducting material from II-VI group [1], the

deposition and characterization of CdS semiconducting

thin films has been received a considerable amount of

interest due to their potential used in the optoelectronic

application [2]. Polycrystalline CdS thin films are

widely used as window material in several

heterojunction solar cells for their favorable optical

properties [3, 4]. Cadmium Sulfide films have been

established as a viable candidate for the absorbing

material in the visible region [5]. Many techniques

have been reported for the deposition of CdS thin film.

These include evaporation, sputtering, chemical bath

deposition, spray pyrolysis [6], metal organic chemical

vapor deposition; molecular beam epitaxy technique

[3], laser ablation, close space sublimation,

electrochemical deposition technique [4], screen

printing, photochemical deposition [7], brush plating,

pulsed laser deposition, physical vapor deposition,

successive ionic layer adsorption and reaction [8]. In

this paper, thin CdS films have been prepared by

thermal evaporation technique. The main task of this

study is a search for studying the effect of annealing

temperatures and the thicknesses on some structural

and electrical properties.

II. Experimental Works

Thin CdS films have been evaporated by Edward

E306A coating system under vacuum of about 2×10-5

mbar, with CdS powder purity of about 99.999%

manufacturer by Balzers Switzerland. These films

deposited on 7059 corning glass slides with different

thicknesses (100, 150, 200, 250 nm) at substrate

temperature about 333K. The prepared films have

annealed at 373, 423 and 473 K. Aluminum used as

electrodes. The CdS powder examined by Phillips X-

Ray diffractometer system was used for structural

analysis with CuKα source. The electrical resistance

and the conductivity were measured by using of the

circuit consists of Keithley 616 digital electrometer and

Memert oven.

III. Results and Discussion

III.1. Structural properties

X-ray diffraction spectra of CdS powder, as prepared

and annealed films with different thicknesses are

shown in figure 1. From this figure it can be observed

that the CdS powder, as prepared and annealed films

with different thicknesses are hexagonal polycrystalline

structure. CdS powder indicated a polycrystalline

consists of pure hexagonal phase and display

characteristic diffraction peaks corresponding to

ASTM cards (American standards for Testing

Materials) at (100), (002), (101), (102), (110), (103),

(112), (004), (202) and (220) planes. This result is in

agreement with those of Ikhmayies and Ikhmayies and

Ahmad-Bitar, [6], Elmas et al [9] El-Assali et al [10]

and Punnoose et al [11]. Atomic force microscopy

(AFM) scan image of CdS powder is shown in figures

International Review of Physics (I.Re.Phy.), Vol. 7, N. 1

ISSN 1971-680X February 2013

Manuscript received and revised October 2012, accepted December 2012 Copy right © 2013 Praise Worthy Prize S.r.l. –All right received

4

2, AFM image shows that the powder is well faceted

crystallites, with linear transversal dimensions larger

than 1.76 nm, contains uniformly packed small grains

and the surface roughness is 0.18 nm. The CdS powder

has a root mean square (RMS) roughness of about 0.24

nm.

Figure 1: The XRD spectrum of CdS powder, as deposited and

annealed films at different annealing temperature and thicknesses.

The x-ray diffraction spectra for 100nm thick of the as

deposited film displayed strong reflection at (002)

plane and weaker intensities at (100), (101), (102),

(110), (103), (112), (004), (202) and (220) planes. One

can observe an increasing in the intensity of peaks and

decreasing in full width at half maximum intensity

(FWHM), which means increasing the crystal growth.

The x-ray diffraction spectra for 150, 200 and 250 nm

thick showed preferred orientation at (002) plane, and

the structural improvement is obviously evident. The

increasing of the annealing temperature causes an

increasing in the intensity of peaks and decreasing in

FWHM. Other peaks disappeared consequently except

(004), this result is due to the rearrangement happened

throw the annealing and improve in the crystalline

nature of the films [8]. This result is in agreement with

those of El-Assali et al. [10] and Punnoose et al. [11].

These results indicate that the process of grains

formation is thermally activated [11]. A comparison

among the spectra on the films in figure1 shows that

there is more crystallization and more orientation of the

crystal growth in the case of thicker films. The plane

(002) became stronger than the other planes, similar

results have found by Ikhmayies and Ahmad-Bitar [6].

Figure 2 The AFM image of CdS powder.

The degree of preferred orientation of CdS films can be

estimated from the peak intensities using the method of

Harris for polycrystalline fiber texture analysis [12].

The degree of the preferred orientation, that is, the

orientation parameter of a certain crystal plane (hkl) in

a polycrystalline films can be determined from the

following equation:

n

hklhkl

hklhkl

cII

IInhklT

)()(

)()()(

(1)

Where Tc(hkl) is the texture coefficient, I(hkl) is the

measured intensity of the peak (khl), I0(hkl) is the

relative intensity of the corresponding peak from a

powder reference and n is the number of peaks (here n

=10). When Tc(002) = n, this means that all the grain of

CdS films are oriented in the (002) plane, and lower

values of Tc(002), means random orientation, as shown

in figure 3. With reduction of CdS film thickness,

Tc(002) decreases and become close to 2.

Figure 3 The effect of annealing temperature on the texture

coefficient of as deposited and annealed CdS thin films with different

thicknesses.

The dhkl spacing has also determined for (002) plane,

its value varied between 3.360Ǻ to3.342Ǻ, which it is

effected by increasing the annealing temperature and

increasing the film thicknesses as given in Table 1. The

value of d(002) has decrease with increasing the texture

3.34 nm

0nm

Eman M. Naser

5

coefficient of the prepared films as shown in figure 4.

The decreasing of d(002) may be due to crystal growth or

crystallite formation.

Figure 4. The relation between d(002) and the texture coefficient of

the prepared CdS films with different thicknesses.

III.2. Electrical properties

Figure 5 illustrates electrical conductivity (lnσ/σ0) as a

function of 103/T, there are two stages of conductivity

through the heating temperature range. In this case, the

first activation energy (Ea1) occurs at higher

temperature range [13]. This activation is due to the

carrier excited into the extended states beyond the

mobility edge. While the second activation energy (Ea2)

occurs at lower temperature range and the conduction

mechanism of this stage is due to the carrier transport

to the localized states near the valence and the

conduction bands [13].

Figure 5. The electrical conductivity behaviors (lnσ/σ0 vs 103/T) for as deposited and annealed CdS thin films at different annealing

temperatures and thicknesses.

These two conduction mechanisms mean that the

electrical conductivity is non-linear with temperature. Ea1 behaved like Ea2 fluctuation with increasing the

annealing temperature as given in Table 1. They are

decreased with increased the film thickness and

increased as duration times increased. The increasing

of activation energies may be attributed the removal of

defect states present in the film [14]. The activation

energy (Ea) can be calculated from the following

equation [15]:

)ln()1( TKE Ba

(2)

Where σₒ is constant represents the intrinsic

conductivity. The electrical conductivity represents a

simple way to measure the energy gap between valance

and conduction band, so that, for intrinsic conduction

2Ea is equal to the energy gap (Eg), and kB is

Boltzmann's constant. The conductivities of the as

deposited and annealed CdS thin were found to

increase with increasing the annealing temperature and

thicknesses. This increasing is attributed to decrease in

the dangling bonds and the density of localized states

inside the gap. Also it can be observed that the

conductivity of 250 nm film thickness is higher than

that of the other thicknesses. The conductivity increase

as thickness increased due to structural improvement as

thickness increase. Similar results have fond by

Ikhmayies and Ahmad-Bitar [6] and Desale et al. [14].

Table 1. The values of d(002) spacing, activation energies Ea1, Ea2

and electrical conductivity σ, versus the annealing temperatures Ta,

for as deposited (dep.) and annealed CdS thin films with different

thicknesses, t.

T

(nm)

Ta

(K)

d(002)

(Ǻ)

Ea1

(meV)

Ea2

(meV)

σ×10-3

(.cm)-1

100

dep. 3.360 760 54.3 0.36

373 3.359 829 72.4 0.42

423 3.357 942 77.1 1.34

473 3.356 976 81.6 1.55

150

dep. 3.355 723 70.8 2.86

373 3.354 819 108 3.33

423 3.352 885 112 4.74

473 3.351 914 139 5.41

200

dep. 3.350 626 90.9 12.9

373 3.349 629 98.3 13.2

423 3.347 635 116 18.4

473 3.346 790 119 27.8

250

dep. 3.345 71.8 11.4 267

373 3.344 76.8 17.6 333

423 3.343 80.7 20.2 392

473 3.341 83.5 23.7 456

The relation between the conductivity and the

crystallite orientation (I(002)/Ihkl) is given in figure 6,

Eman M. Naser

6

it is obviously that the increasing of crystallite

orientation lead to increase the conductivity.

Figure 6. The relation between the conductivity and the crystallite

orientation of CdS thin films with different thicknesses.

IV. CONCLUSIONS

Cadmium sulfide films were hexagonal

polycrystalline structure. The texture coefficient

affected by annealing temperature and the film

thicknesses.

The electrical conductivity displays two stages of

conductivity for all thicknesses. The conductivity

increases with increasing the annealing temperature

and thicknesses. The conductivity of the film of

250nm is higher than that of the other thicknesses.

Thermal activation energies for as deposited and

annealed CdS thin films increase with increasing

the annealing temperature and thicknesses.

References [1] A. S. Khomane. 2011. Archives of Applied Science

Research, 3, 273-279.

[2] S. A. Vanalakar et al. 2010, Journal of

Nanomaterials and Biostructures, 5, 805-810.

[3] A. I. Khudiar, S. M. Zulfequar, Z. H. Khan. 2010.

Chalcogenide Letters, 7, 291-298

[4] D. Saikia, P. K. Gogoi, P. K. Saikia. 2010.

Chalcogenide Letters, 7, 317 – 324

[5] I.S. Nandhakumar et al. 2004. Chem. Comman., 4

,1374-1375

[6] S.J. Ikhmayies, R. N. Ahmad-Bitar. 2008.

American Journal of Applied Science, 5, 1141-

1143.

[7] V. B. Sanap, B. H. Pawar. 2009. Chalcogenide

Letters, 6, 415-419.

[8] M. Thambidurai et al. 2010. J. Mater. Sci. Technol,

26, 193-199.

[9] S. Elmas, S. Ozder, V. Bilgin. 2012. Acta Physica

Polonica A, 1, 121.

[10] K.El Assali et al. 2000. Phys. State Sol. (a), 178,

701.

[11] A. Punoose et al. 2000. Phys Stat. Sol. (a), 177,

453-457.

[12] G. B. Harris. 1952. Philos. Mag., 43, 113-123.

[13] J. Simson, J.J. Aolre. Molecular Semiconductors.

Berlin: Springer-Verlag, 1985.

[14] D. J. Desale el al. 2011. Advances in Applied

Science Research, 2, 417-425.

[15] M.H. Brodsky. Amorphous Semiconductors,

Berlin: Springer-Verlag press, 1979.

AUTHORS’ INFORMATION Author affiliation; University of Baghdad, College of Sciences,

Department of physics

Corresponding author: Eman M. Nasir

E-Mail: emnasir_7@yahoo.com

Place and/ date of birth: Iraq -Baghdad / 1973

Scientific Degree : B. Sc Physics, 1991, College of Science/

University of Baghdad-Iraq.

M. Sc Thin Film, 1999, College of

Science / University of Baghdad –Iraq.

Ph.D. Thin Film, 2005, College of Science / University of Baghdad –Iraq.

Specialization :Solid state physics, Thin Film,

Semiconductor Detectors. Carrier : Assistant Prof.

Author’s major field of study: Detectors applications.

Work Address : Department of Physics / College of Science / University of Baghdad.

Eman M. Naser

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International Reviw of Physics Vol. 7, N. 1

International Review of Physics, Vol. 7, N. 1

7

1971-6796(201302)7:1; 1-A

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