INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue VIII August 2025

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Thickness Dependent Thermoelectric Properties of Pb0.4In0.6Se Thin

Films Deposited by Physical Evaporation Technique
K. S. Chaudhari

S.V. S’s Dadasaheb Rawal College, Dondaicha, Dist Dhule (M.S.), India

DOI: https://doi.org/10.51244/IJRSI.2025.120800086

Received: 10 Aug 2025; Accepted: 15 Aug 2025; Published: 06 September 2025

ABSTRACT

Thin films having different thickness of Pb0.4In0.6Se were deposited by thermal evaporation techniques, onto
precleaned amorphous glass substrate. The structural properties of films were evaluated by XRD, optical
microscopy, SEM and EDAX. The thermoelectric of annealed thin films have been evaluated. Thermoelectric
Properties shows a positive sign exhibiting p- type nature of films. Fermi energy and scattering parameter were
determined. The calculated values of Fermi energy and scattering parameter are 4 to 0.4 eV and 0.184 to 0.127
respectively. The X-ray diffraction analysis confirms that films are polycrystalline having orthorhombic
structure. The average grain size is found to be 27.08 nm.

Keywords: optical microscopy, XRD, SEM, EDAX, thermoelectric properties.

INTRODUCTION

In the recent years a fair amount of research has been carried out on PbSe and InSe because of their narrow
band gap [1] and application in devices such as infrared devices [2,3], diodes [2,5], lasers, thermo photovoltaic
conversions, solar cells [2-5], Opto electronic devices, [6- 8] etc. Currently, electronic and optoelectronic
industries provide some of the largest markets and challenges for thin film semiconductors. Current techniques
for growth of these materials include physical methods. Physical methods are expensive but give relatively
more reliable and reproducible results [9, 10]. InSe and PbSe based materials are of considerable technological
interest for application to high speed and optoelectronic devices because of their high electron mobility and
low effective electron mass [11]. Materials with good thermoelectric properties became a part and parcel of
the modern technology because of their potential use in cooling systems [12]. The lead chalcogenides exhibit
very interesting photoelectric, photoconducting, thermoelectric, optical and semiconducting properties [13].
Lead Selenide is important material of IV- VI group compounds. Due to its potential applications, thin films of
lead chalcogenides have been extensively studied by doping n or p – type, so that they may be used in various
solid state devices [14, 15]. From the study of literature review, it can be seen that no attempt has been made to
study the variation of surface morphological study by change in thickness of thin films. In present work effect
of film thickness on surface morphology over the thickness range 1000 – 3000 Ǻ has been investigated. An
attempt has been made to evaluate the electrical parameters such as Fermi energy, scattering parameter and
optical band gap.

Majority of these compounds have been reported to be grown in the crystalline form. Thin films preparation
with direct materials do not shows any contamination of impurities, therefore the pure form of powder of
lead selenide was used for synthesis it.

EXPERIMENTAL

The compound ingot of Pb0.4In0.6Se was obtained by mixing quantities of high-purity (99.999%) lead, indium
and selenium powder in the atomic proportion 2:3:5. The mixture was sealed in an evacuated quartz tube at a
pressure of 10-5 torr and heated at 1120 K for 36h and then quenched in ice cooled water. Polycrystalline
Pb0.4In0.6Se films have been deposited by physical evaporation technique under vacuum of about 10-5torr. The
substrate to source distance was kept 20cm. The samples of different thicknesses were deposited under similar

INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue VIII August 2025

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conditions. The thickness of the films was controlled by quartz crystal thickness monitor model No. DTM-101
provided by Hind-HiVac. The deposition rate was maintained 5-10 Ǻ/sec throughout sample preparation.
Before evaporation, the glass substrates were cleaned thoroughly using concentrated chromic acid, detergent,
isopropyl alcohol and distilled water.

X – Ray diffractogram (Rigaku Miniflex, Japan) were obtained of these samples to find out structural
information and to identify the film structure qualitatively. The scanning angle (2θ) range was from 200 - 800

(CuKα line). Optical absorption was measured by UV-VIS spectrophotometer model no. Shimadzu -2450. The
thermo electric power of samples was measured by TEP set up using model no. DMV – 001, “Scientific
Equipments, Roorkee”, as a function of thickness and temperature.

RESULTS AND DISCUSSION

Structural characterization

The structural composition of the grown films was studied through the optical microscopy, XRD analysis,
SEM and EDAX.

Fig. 1 Micrograph of Pb0.4In0.6Se film of thickness 2000 Ǻ

Fig. 1 shows the micrograph of Pb0.4In0.6Se of thickness 2000 Ǻ indicates particles are uniformly distributed
over the surface. Further confirmation of the structure of the grown films was carried out using the x-ray
diffraction pattern in Fig. 2.

Fig. 2 XRD of Pb0.4In0.6Se of thickness 1000 Ǻ

Fig. 2 shows the XRD pattern of Pb0.4In0.6Se thin film prepared at substrate temperature of 303k. The plane
indices are obtained by comparing the intensities and position of the peaks with JCPDS data. There is no
JCPDS slandered data available for different composition of Pb1-xInxSe. The presence of large number of peaks
indicates that the films are polycrystalline in nature; exhibit the formation of the orthorhombic phase of
Pb0.4In0.6Se. The unit cell volume is 768.23 and lattice parameters are a = 15.2960 Ǻ, b = 12.3080 Ǻ and c =

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4.0806 Ǻ. The structural parameters of Pb0.4In0.6Se thin film shows that the film has average grain size of
3.432 nm for the film of thickness 1000 Å.

Fig. 3 shows typical SEM micrograph of Pb0.4In0.6Se thin film of thickness 2500 Ǻ. The surfaces of
Pb0.4In0.6Se deposits are showing spheres of 50nm-0.4µm diameter. The micrograph also consists of nano
wires oriented in two directions. The surface roughness is seems to be improved greatly by the addition of
third element. The EDAX spectral analysis for the Pb0.4In0.6Se thin film prepared by thermal evaporation
technique is shown in Fig. 4. The obtained percentages of the constituent elements in all investigated films
indicate that samples are nearly stoichiometric. The obtained results give support for the quality of the
prepared Pb0.4In0.6Se thin films by thermal evaporation technique. The actual atomic % for Pb0.4In0.6Se
compositions of lead, indium and selenium are in the ratio of 19.90:29.31: 50.79.

Fig. 3 SEM image of Pb0.4In0.6Se thin film of 2500 Ǻ

Fig. 4 EDS Spectra of Pb0.4In0.6Se thin film

Thermo Electrical Properties of Pb0.4In0.6Se thin films

The TEP is measured by integral method [13, 16]. The graphical representation of thermo emf verses change
in temperature for different thickness of Pb0.4In0.6Se thin films are shown in fig. 5 and fig. 6 represents the
Seebeck coefficient versus 1/∆T for different thicknesses of thin film. From this graph the Fermi energy and
scattering parameter are calculated and represented in Table 1, the Fermi energy of Pb0.4In0.6Se thin films is
thickness dependant, as thickness increases Fermi energy decreases, and as thickness increases scattering
parameter increases. A Thermoelectric power measurement shows that Pb0.4In0.6Se is a P type material due to
positive slop of the graph.[15-17].

INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue VIII August 2025

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Fig 5 Plot of Thermo emf verses ΔT

Fig 6 Plot of Seebeck coefficient versus 1/∆T

Table1 Estimated parameter from TEP measurement

Thickness Ǻ Fermi Energy (e V) Scattering parameter

1000 4 0.124

1500 0.6 0.1414

2000 1.3 0.188

2500 2.5 0.213

3000 0.4 0.227

CONCLUSION

From the temperature dependence of Thermoelectric Power, the Fermi energy Ef and scattering parameter are
determined is thickness dependent The XRD shows that all the films prepared were polycrystalline
orthorhombic structure. Indium Selenide and Lead Selenide and its intermediate combination, thin films
exhibit promising thermoelectric properties due to their layered structure and tunable electrical characteristics.

INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue VIII August 2025

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These films were shown potential for applications in thermoelectric power generation, photovoltaic’s and other
optoelectronic devices.

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