Polycrystalline thin films of tungsten dieseline were prepared by using rarely reported technique of electron beam evaporation for transition metal dichalcogenides. High purity (99.999 %) reacted compound was used as starting material for the preparation of WSe2 thin films. Various parameters and conditions are outlined which were used for deposition of thin films. The prepared films were characterized using EDAX spectrum, X-ray diffraction, Electron diffraction, Scanning electron microscopy and optical absorption spectroscopy methods. The as grown films were found to be partially transparent, uniform and well adherent. Uniformity was confirmed by SEM. WSe2 film was found in stoichiometric proportion. XRD pattern as well as TEM images revealed the fact that the deposited films are polycrystalline in nature having hexagonal structure. From the study of optical absorption spectra it is found that the prepared films show direct allowed transition with optical band gap of 1.89 eV. The results are in good agreement with the earlier published data of WSe2 thin films deposited by different techniques.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2959

Patel, K.D.

Patel, Maul M.

Pathak, V.M.

Srivastava, R.

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ  Vol. 4 No 3, 03001(3pp) (2012) Том 4 № 3, 03001(3cc) (2012)   2077-6772/2012/4(3)03001(3) 03001-1  2012 Sumy State University Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide  Polycrystalline Thin Film  Mayur M. Patel*, K.D. Patel, V.M. Pathak, R. Srivastava  Department of Physics, Sardar Patel University, Vallabh Vidyanagar, 388 120, Gujara, India  (Received 18 June 2012; published online 29 October 2012)  Polycrystalline thin films of tungsten dieseline were prepared by using rarely reported technique of electron beam evaporation for transition metal dichalcogenides. High purity (99.999 %) reacted compound was used as starting material for the preparation of WSe2 thin films. Various parameters and conditions are outlined which were used for deposition of thin films. The prepared films were characterized using EDAX spectrum, X-ray diffraction, Electron diffraction, Scanning electron microscopy and optical absorp-tion spectroscopy methods. The as grown films were found to be partially transparent, uniform and well adherent. Uniformity was confirmed by SEM. WSe2 film was found in stoichiometric proportion. XRD pat-tern as well as TEM images revealed the fact that the deposited films are polycrystalline in nature having hexagonal structure. From the study of optical absorption spectra it is found that the prepared films show direct allowed transition with optical band gap of 1.89 eV. The results are in good agreement with the ear-lier published data of WSe2 thin films deposited by different techniques.  Keywords: ē-Beam Evaporation, WSe2 Thin Films, Structural analysis, Optical Studies, SEM, TEM.   PACS numbers: 68.55aj, 73.90 + F                                                             * physics.mayur@gmail.com 1. INTRODUCTION  The various chalcogenide thin films like WSe2, MoSe2, WS2, CdS, CdSe, and SnSe have been prepared and characterized for structural, optical and electrical studies by above mention technique [1-9]. Transition metal dichalcogenides like WSe2, MoSe2 etc. can be used to convert solar energy to electrical energy effi-ciently in the thin film structure [10]. Tungsten diselenide (WSe2) single crystals and thin films have attractive properties like bandgap in the range of 1 – 2 eV which is most suitable range of energy to tap so-lar spectrum for soalr cell applications. There have been several methods like chemical vapour deposition (CVD), R. F. Sputtering, Spray Pyrolysis, Electrodepo-sition, Solid reaction, Chemical bath deposition (CBD) etc. [1, 11-14] which have been reported for the prepa-ration of polycrystalline thin films of tungsten diselenide. Present paper reports the results of our investiga-tions regarding deposition of WSe2 thin films using electron beam evaporation technique and chemical, structural and optical characterization of prepared films. The preparative parameters like, vacuum condi-tion, deposition rate, thickness, deposition temperature is reported in detailed in this paper.  2. EXPERIMENTAL DETAILS   Thin films of 1732 Å were deposited on chemically and ultrasonically cleaned glass substrates with the help of 3 kWatt 180  ē-beam source attached to a box-coater vacuum system (BC-300, Hindhivac-Banglore). All the gadgets of the vacuum chamber were first cleaned by acetone.     2.1 Substrate Cleaning  The deposition was done on glass slides of 4 inch × 2 inch dimensions. These substrates were cleaned by ultrasonic vibrations followed by washing successively with detergent and acetone.  2.2 Source Materials  Analytical grade high purity reacted tungsten diselenide powder (99.999 %) was used to prepare thin films and it was placed in well cleaned water cooled copper crucible. The cleaned substrates were fixed on the substrate holder and digital quartz crystal sensor was placed in close vicinity to them for the in situ thickness meas-urements. The chamber was evacuated at a pressure of 0.5 × 10 – 5 Torr by the combination of rotary and diffu-sion pump. When vacuum of 10 – 6 Torr was attained in the vacuum chamber, the emission current of filament was gradually raised to generate electron beam which is accelerated toward the water cooled crucible with the help of magnetic field. The accelerated electrons lose their energy by colliding to powdered source material and generate heat to raise the temperature in excess of the melting point of WSe2. This allowed the evapora-tion of WSe2 material. The rate of deposition was kept between 1 – 3.5 Ås – 1 till the final thickness of 1.732 kÅ of deposited films was attained.  2.3 Characterization of WSe2 Thin Film   The thickness of deposited thin films was measured by in situ digital quartz crystal monitor (Hi-Tech DTM 101). The JEOL JSM 5410 SEM with an Oxford Link Isis-Energy Dispersive X-ray Spectrometer (EDS) was used for the chemical characterization and electron microscopy. The X-ray diffraction analysis of WSe2 thin  MAYUR M. PATEL, K.D. PATEL, V.M. PATHEK, ET AL.  J. NANO- ELECTRON. PHYS. 4, 03001 (2012)   03001-2 film has been carried out at 303 K using X-Ray Diffrac-tometer (D8 Advance BRUKER AXS) with CuKα radia-tion of wave length 1.54 Å. For TEM studies, films were deposited simultanous-ly on freshly cleaved NaCl crystals also. The optical characterization of films were carried out using the UV-VIS-NIR spectrophotometer (Perkin Elmer-USA, Model: Lambda 19) in the range of 200 nm to 2500 nm wavelength.  3. RESULTS AND DISCUSSION  3.1 Stoichiometric Analysis  EDAX spectrum (Fig. 1(a)) confirmed that the depo-sition of WSe2 films comprised of W and Se along with presence of oxygen content. The reason of presence of Oxygen in deposited films may be due to poor level of vacuum of the order of 0.5 × 10 – 5 Torr. No other ele-ments were observed within the limits of sensitivity. Neglecting the oxygen contents, the chemical formula assigned to the deposited films can be W0.94Se2.06.    Fig. 1 – EDAX spectrum for WSe2 thin film  Table 1 – Composition (Wt %) of WSe2 Thin Film    3.2 Crystallographic and Morphological Studies  The XRD pattern of WSe2 thin film is shown in Fig. 2. Comparison of observed ‘d’ values with standered ‘d’ values confirms that ē beam evaporated thin film shows hexagonal structure (JCPDS-38-1388). The XRD pattern shows the highest intensity reflection peak at 2θ = 13.96  with d = 6.33 Ǻ (002). The diffused background is due to amorphous glass substrate. Along with (002) planes (103), (006), (008) planes were ob-served. The lattice parameters ‘a and c’ of WSe2 film were found to be 3.25 Å, and 12.97 Å respectively. These val-ues are in good agreements with the earlier reported [1, 15, 16]. The crystallite size was calculated by using Scherrer formula for highest intensity peaks. The crys-tallite size of WSe2 thin film was found to be 59.31 Å. The crystallographic data are shown in Table 2(a).  Table 2(b) shows the comparison of parameters of thin film of WSe2 deposited using different techniques.    Fig. 2 – XRD diffrectogram for WSe2 thin film  Table 2(a) – Crystallographic data of WSe2 Thin Film   d- Values (Å) hkl planes Grain Size (Å) Cell Parame-ters (Å) Observed TEM XRD TEM 6.33  002  59.31  a = b = 3.25 c = 12.97 2.36 3.28 103 004 62.26 2.14 2.21 006 006 33.78 1.61 1.78 008 008 64.80  Table 2(b) – Crystallographic data of WSe2 thin films depos-ited by various techniques   Deposition Technique Optical Bandgap (eV) Grain Size (Å) Cell Para- meters (Å) Ref. ē-beam Evaporation Technique (Present case) 1.89 59.31 a = 3.25 c = 12.97  chemical synthetic route 1.48 159 a = 3.28 c = 13.00 [1] Sputtering 1.91 450 -------- [17] Synthesis by tarnish-ing 1.25 50 – 100 a = 3.29 c = 13.1 [18] Electrodep-osition. 1.46 2 – 15 a = 3.35 c = 12.59 [19]  The electron diffraction pattern of WSe2 thin film (Fig. 3(a)) shows sharp rings corresponding to d = 3.28 Å, 2.21 Å, 1.78 Å with (004), (006), (008) planes respectively. This again confirms the hexagonal phase in the prepared films. The SEM micrograph of WSe2 thin film is shown in Fig. 3(b). It can be seen from here that the WSe2 film is almost homogenous with small cracks and pinhole with stacked layer type features. Element Weight% Chemical Formula EDAX Expected EDAX Expected O 5.13 0.0 W0.94Se2.06 (Neglecting oxygen content) WSe2 Se 43.81 46.21 W 51.06 53.79 Totals 100.00 100.00  CHEMICAL, STRUCTURAL AND OPTICAL PROPERTIES OF Ē-BEAM… J. NANO- ELECTRON. PHYS. 4, 03001 (2012)   03001-3     a    b  Fig. 3 – Electron diffraction image (a) SEM micrograph (b) for WSe2 thin film  3.3 Optical Studies  The optical absorption spectra of tungsten diselenide films deposited onto glass substrates were studied at room temperature in the wavelength of 200 – 2500 nm. The optical study shows that the film is high-ly absorbing in nature in the energy range 1.7 – 3.3 eV and it show the presence of absorption edge. The optical band gap ‘Eg’ was determined from vari-ation of ( hν)2 with photon energy hν (Fig. 4). The line-ar nature of plot indicates the existence of direct transi-tion and its extrapolation to energy axis (  = 0) gives bandgap of 1.89 eV for WSe2 films which is in good agreement with values reported earlier [1, 17].    Fig. 4 – Plot of ( hν) 2 vs. photon energy hν  4. CONCLUSION   WSe2 thin film can be deposited by using ē-beam evaporation technique onto non-conducting glass. The X-ray diffraction revels that the films are polycrystal-line in nature and posses hexagonal structure and it is confirmed against TEM studies also. The SEM micro-graph shows the uniformity of film. Optical study shows that WSe2 film has optical absorption coefficient. The direct bandgap obtained are 1.89 eV for film.  ACKNOLEDGMENT   Authors (MMP, KDP) are thankful to University Grant Commission (UGC) – New Delhi for providing financial support received in the form of UGC major research project (Grant reference no. : F33-8/2007(SR)).  REFERENCES   1. P.P. Hankare, A.H. Manikshete, D.J. Sathe, P.A. Chate, K.C. Rathod, Mater. Chem. Phys. 113, 189 (2009). 2. S. Chandra, D.P. Singh, D.C. Srivastava, S.N. Sahu, J. Phys. D.: Appl. Phys. 17, 2125 (1984). 3. R. Bichsel, F. Levy, H.J. Mathieu, Thin Solid Films 131, 87 (1985). 4. M. Ganchev, N. Stratieva, E. Tzvetkova, I. Gadjov, J. Ma-ter. Sci.: Mater. El. 14, 847 (2003). 5. J. Pouzet, J.C. Bernede, Rev. Phys. Appl. 25, 807 (1990). 6. M.M. Abd El-Raheem, Journal of Ovonic Research 4 №6, 165 (2008). 7. Wolfgang K. Hofmann, J. Mater. Sci. 23, 3981 (1988). 8. S. Chandra, D.P. Singh, P.C. Srivastava S.N. Sahu, J. Phys. D: Appl. Phys. 17, 2125 (1984). 9. K. Ellmer, C. Stock, K. Diesner, I. Sieber, J. Cryst. Growth 182, 389 (1997). 10. W. Kautek, J. Gobrechet, H. Gerisher, Ber. Bunsenges. Phys. Chem. 84, 1034 (1980). 11. P.P. Hankare, P.A. Chate, S.D. Delekar, V.M. Bhuse, M.R. Asabe, B.V. Jadhav, K.M. Garadkar, J. Cryst. Growth 291, 40 (2006). 12. D.E. Miller, First year Prog. Rep. (Lawrence Livermore Laboraory, CA). 13. C.R. Cabrera, H.D. Abruna, J. Phys. Chem. 89, 1279 (1985). 14. J. Jebraja Devadasan, C. Sanjeeviraja, M. Jayachandhran, Mater. Chem. Phys. 77, 397 (2002).  15. S.M. Delphine, M. Jayachandran, C. Sanjeeviraja, Mater. Chem. Phys. 81, 78 (2003). 16. G. Salitera, G. Hodes, E. Klein, R. Tenne, Thin Solid Films 245, 186 (1994). 17. O. Lignier, G. Couturier, J. Tedd, D. Gonbeau, J. Salardenne, Thin Solid Films 299, 45 (1997). 18. A. Khelilt, H. Essaidit, J.C. Bernede, A. Bouacheriat, J. Pouzet, J. Phys.: Condens. Mater. 6, 8527 (1994). 19. J. Jebaraj Devadasan, C. Sanjeeviraja, M. Jayachandran, Mater. Chem. Phys. 77, 397 (2002).  

Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide Polycrystalline Thin Film

SocioEconomic Challenges Journal (Sumy State University)

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ  
Vol. 4 No 3, 03001(3pp) (2012) Том 4 № 3, 03001(3cc) (2012) 
 
 
2077-6772/2012/4(3)03001(3) 03001-1  2012 Sumy State University 
Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide  
Polycrystalline Thin Film 
 
Mayur M. Patel*, K.D. Patel, V.M. Pathak, R. Srivastava 
 
Department of Physics, Sardar Patel University, Vallabh Vidyanagar, 388 120, Gujara, India 
 
(Received 18 June 2012; published online 29 October 2012) 
 
Polycrystalline thin films of tungsten dieseline were prepared by using rarely reported technique of 
electron beam evaporation for transition metal dichalcogenides. High purity (99.999 %) reacted compound 
was used as starting material for the preparation of WSe2 thin films. Various parameters and conditions 
are outlined which were used for deposition of thin films. The prepared films were characterized using 
EDAX spectrum, X-ray diffraction, Electron diffraction, Scanning electron microscopy and optical absorp-
tion spectroscopy methods. The as grown films were found to be partially transparent, uniform and well 
adherent. Uniformity was confirmed by SEM. WSe2 film was found in stoichiometric proportion. XRD pat-
tern as well as TEM images revealed the fact that the deposited films are polycrystalline in nature having 
hexagonal structure. From the study of optical absorption spectra it is found that the prepared films show 
direct allowed transition with optical band gap of 1.89 eV. The results are in good agreement with the ear-
lier published data of WSe2 thin films deposited by different techniques. 
 
Keywords: ē-Beam Evaporation, WSe2 Thin Films, Structural analysis, Optical Studies, SEM, TEM. 
 
 PACS numbers: 68.55aj, 73.90 + F 
 
 
                                                          
* physics.mayur@gmail.com 
1. INTRODUCTION 
 
The various chalcogenide thin films like WSe2, 
MoSe2, WS2, CdS, CdSe, and SnSe have been prepared 
and characterized for structural, optical and electrical 
studies by above mention technique [1-9]. Transition 
metal dichalcogenides like WSe2, MoSe2 etc. can be 
used to convert solar energy to electrical energy effi-
ciently in the thin film structure [10]. Tungsten 
diselenide (WSe2) single crystals and thin films have 
attractive properties like bandgap in the range of 1 –
 2 eV which is most suitable range of energy to tap so-
lar spectrum for soalr cell applications. There have 
been several methods like chemical vapour deposition 
(CVD), R. F. Sputtering, Spray Pyrolysis, Electrodepo-
sition, Solid reaction, Chemical bath deposition (CBD) 
etc. [1, 11-14] which have been reported for the prepa-
ration of polycrystalline thin films of tungsten 
diselenide. 
Present paper reports the results of our investiga-
tions regarding deposition of WSe2 thin films using 
electron beam evaporation technique and chemical, 
structural and optical characterization of prepared 
films. The preparative parameters like, vacuum condi-
tion, deposition rate, thickness, deposition temperature 
is reported in detailed in this paper. 
 
2. EXPERIMENTAL DETAILS  
 
Thin films of 1732 Å were deposited on chemically 
and ultrasonically cleaned glass substrates with the 
help of 3 kWatt 180  ē-beam source attached to a box-
coater vacuum system (BC-300, Hindhivac-Banglore). 
All the gadgets of the vacuum chamber were first 
cleaned by acetone.  
 
 
 
2.1 Substrate Cleaning 
 
The deposition was done on glass slides of 
4 inch × 2 inch dimensions. These substrates were 
cleaned by ultrasonic vibrations followed by washing 
successively with detergent and acetone. 
 
2.2 Source Materials 
 
Analytical grade high purity reacted tungsten 
diselenide powder (99.999 %) was used to prepare thin 
films and it was placed in well cleaned water cooled 
copper crucible. 
The cleaned substrates were fixed on the substrate 
holder and digital quartz crystal sensor was placed in 
close vicinity to them for the in situ thickness meas-
urements. The chamber was evacuated at a pressure of 
0.5 × 10 – 5 Torr by the combination of rotary and diffu-
sion pump. When vacuum of 10 – 6 Torr was attained in 
the vacuum chamber, the emission current of filament 
was gradually raised to generate electron beam which 
is accelerated toward the water cooled crucible with the 
help of magnetic field. The accelerated electrons lose 
their energy by colliding to powdered source material 
and generate heat to raise the temperature in excess of 
the melting point of WSe2. This allowed the evapora-
tion of WSe2 material. The rate of deposition was kept 
between 1 – 3.5 Ås – 1 till the final thickness of 1.732 kÅ 
of deposited films was attained. 
 
2.3 Characterization of WSe2 Thin Film  
 
The thickness of deposited thin films was measured 
by in situ digital quartz crystal monitor (Hi-Tech DTM 
101). The JEOL JSM 5410 SEM with an Oxford Link 
Isis-Energy Dispersive X-ray Spectrometer (EDS) was 
used for the chemical characterization and electron 
microscopy. The X-ray diffraction analysis of WSe2 thin 
 MAYUR M. PATEL, K.D. PATEL, V.M. PATHEK, ET AL.  J. NANO- ELECTRON. PHYS. 4, 03001 (2012) 
 
 
03001-2 
film has been carried out at 303 K using X-Ray Diffrac-
tometer (D8 Advance BRUKER AXS) with CuKα radia-
tion of wave length 1.54 Å. 
For TEM studies, films were deposited simultanous-
ly on freshly cleaved NaCl crystals also. The optical 
characterization of films were carried out using the 
UV-VIS-NIR spectrophotometer (Perkin Elmer-USA, 
Model: Lambda 19) in the range of 200 nm to 2500 nm 
wavelength. 
 
3. RESULTS AND DISCUSSION 
 
3.1 Stoichiometric Analysis 
 
EDAX spectrum (Fig. 1(a)) confirmed that the depo-
sition of WSe2 films comprised of W and Se along with 
presence of oxygen content. The reason of presence of 
Oxygen in deposited films may be due to poor level of 
vacuum of the order of 0.5 × 10 – 5 Torr. No other ele-
ments were observed within the limits of sensitivity. 
Neglecting the oxygen contents, the chemical formula 
assigned to the deposited films can be W0.94Se2.06. 
 
 
 
Fig. 1 – EDAX spectrum for WSe2 thin film 
 
Table 1 – Composition (Wt %) of WSe2 Thin Film  
 
 
3.2 Crystallographic and Morphological Studies 
 
The XRD pattern of WSe2 thin film is shown in 
Fig. 2. Comparison of observed ‘d’ values with 
standered ‘d’ values confirms that ē beam evaporated 
thin film shows hexagonal structure (JCPDS-38-1388). 
The XRD pattern shows the highest intensity reflection 
peak at 2θ = 13.96  with d = 6.33 Ǻ (002). The diffused 
background is due to amorphous glass substrate. Along 
with (002) planes (103), (006), (008) planes were ob-
served. 
The lattice parameters ‘a and c’ of WSe2 film were 
found to be 3.25 Å, and 12.97 Å respectively. These val-
ues are in good agreements with the earlier reported [1, 
15, 16]. The crystallite size was calculated by using 
Scherrer formula for highest intensity peaks. The crys-
tallite size of WSe2 thin film was found to be 59.31 Å. 
The crystallographic data are shown in Table 2(a).  
Table 2(b) shows the comparison of parameters of thin 
film of WSe2 deposited using different techniques. 
 
 
 
Fig. 2 – XRD diffrectogram for WSe2 thin film 
 
Table 2(a) – Crystallographic data of WSe2 Thin Film  
 
d- Values (Å) hkl planes Grain 
Size 
(Å) 
Cell 
Parame-
ters 
(Å) 
Observed TEM XRD TEM 
6.33  002  59.31  
a = b = 3.25 
c = 12.97 
2.36 3.28 103 004 62.26 
2.14 2.21 006 006 33.78 
1.61 1.78 008 008 64.80 
 
Table 2(b) – Crystallographic data of WSe2 thin films depos-
ited by various techniques  
 
Deposition 
Technique 
Optical 
Bandgap 
(eV) 
Grain 
Size 
(Å) 
Cell Para- 
meters 
(Å) 
Ref. 
ē-beam 
Evaporation 
Technique 
(Present 
case) 
1.89 59.31 
a = 3.25 
c = 12.97 
 
chemical 
synthetic 
route 
1.48 159 
a = 3.28 
c = 13.00 
[1] 
Sputtering 1.91 450 -------- [17] 
Synthesis 
by tarnish-
ing 
1.25 
50 –
 100 
a = 3.29 
c = 13.1 
[18] 
Electrodep-
osition. 
1.46 
2 –
 15 
a = 3.35 
c = 12.59 
[19] 
 
The electron diffraction pattern of WSe2 thin film 
(Fig. 3(a)) shows sharp rings corresponding to 
d = 3.28 Å, 2.21 Å, 1.78 Å with (004), (006), (008) planes 
respectively. This again confirms the hexagonal phase 
in the prepared films. 
The SEM micrograph of WSe2 thin film is shown in 
Fig. 3(b). It can be seen from here that the WSe2 film is 
almost homogenous with small cracks and pinhole with 
stacked layer type features. 
Element Weight% Chemical Formula 
EDAX Expected EDAX Expected 
O 5.13 0.0 
W0.94Se2.06 
(Neglecting 
oxygen content) 
WSe2 Se 43.81 46.21 
W 51.06 53.79 
Totals 100.00 100.00 
 CHEMICAL, STRUCTURAL AND OPTICAL PROPERTIES OF Ē-BEAM… J. NANO- ELECTRON. PHYS. 4, 03001 (2012) 
 
 
03001-3 
   
 
a 
 
 
 
b 
 
Fig. 3 – Electron diffraction image (a) SEM micrograph (b) for 
WSe2 thin film 
 
3.3 Optical Studies 
 
The optical absorption spectra of tungsten 
diselenide films deposited onto glass substrates were 
studied at room temperature in the wavelength of 200 –
 2500 nm. The optical study shows that the film is high-
ly absorbing in nature in the energy range 1.7 – 3.3 eV 
and it show the presence of absorption edge. 
The optical band gap ‘Eg’ was determined from vari-
ation of ( hν)2 with photon energy hν (Fig. 4). The line-
ar nature of plot indicates the existence of direct transi-
tion and its extrapolation to energy axis (  = 0) gives 
bandgap of 1.89 eV for WSe2 films which is in good 
agreement with values reported earlier [1, 17]. 
 
 
 
Fig. 4 – Plot of ( hν) 2 vs. photon energy hν 
 
4. CONCLUSION  
 
WSe2 thin film can be deposited by using ē-beam 
evaporation technique onto non-conducting glass. The 
X-ray diffraction revels that the films are polycrystal-
line in nature and posses hexagonal structure and it is 
confirmed against TEM studies also. The SEM micro-
graph shows the uniformity of film. Optical study 
shows that WSe2 film has optical absorption coefficient. 
The direct bandgap obtained are 1.89 eV for film. 
 
ACKNOLEDGMENT  
 
Authors (MMP, KDP) are thankful to University Grant 
Commission (UGC) – New Delhi for providing financial 
support received in the form of UGC major research 
project (Grant reference no. : F33-8/2007(SR)). 
 
REFERENCES 
 
 
1. P.P. Hankare, A.H. Manikshete, D.J. Sathe, P.A. Chate, 
K.C. Rathod, Mater. Chem. Phys. 113, 189 (2009). 
2. S. Chandra, D.P. Singh, D.C. Srivastava, S.N. Sahu, J. 
Phys. D.: Appl. Phys. 17, 2125 (1984). 
3. R. Bichsel, F. Levy, H.J. Mathieu, Thin Solid Films 131, 
87 (1985). 
4. M. Ganchev, N. Stratieva, E. Tzvetkova, I. Gadjov, J. Ma-
ter. Sci.: Mater. El. 14, 847 (2003). 
5. J. Pouzet, J.C. Bernede, Rev. Phys. Appl. 25, 807 (1990). 
6. M.M. Abd El-Raheem, Journal of Ovonic Research 4 №6, 
165 (2008). 
7. Wolfgang K. Hofmann, J. Mater. Sci. 23, 3981 (1988). 
8. S. Chandra, D.P. Singh, P.C. Srivastava S.N. Sahu, J. 
Phys. D: Appl. Phys. 17, 2125 (1984). 
9. K. Ellmer, C. Stock, K. Diesner, I. Sieber, J. Cryst. Growth 
182, 389 (1997). 
10. W. Kautek, J. Gobrechet, H. Gerisher, Ber. Bunsenges. 
Phys. Chem. 84, 1034 (1980). 
11. P.P. Hankare, P.A. Chate, S.D. Delekar, V.M. Bhuse, 
M.R. Asabe, B.V. Jadhav, K.M. Garadkar, J. Cryst. Growth 
291, 40 (2006). 
12. D.E. Miller, First year Prog. Rep. (Lawrence Livermore 
Laboraory, CA). 
13. C.R. Cabrera, H.D. Abruna, J. Phys. Chem. 89, 1279 
(1985). 
14. J. Jebraja Devadasan, C. Sanjeeviraja, M. Jayachandhran, 
Mater. Chem. Phys. 77, 397 (2002).  
15. S.M. Delphine, M. Jayachandran, C. Sanjeeviraja, Mater. 
Chem. Phys. 81, 78 (2003). 
16. G. Salitera, G. Hodes, E. Klein, R. Tenne, Thin Solid 
Films 245, 186 (1994). 
17. O. Lignier, G. Couturier, J. Tedd, D. Gonbeau, J. Salardenne, 
Thin Solid Films 299, 45 (1997). 
18. A. Khelilt, H. Essaidit, J.C. Bernede, A. Bouacheriat, 
J. Pouzet, J. Phys.: Condens. Mater. 6, 8527 (1994). 
19. J. Jebaraj Devadasan, C. Sanjeeviraja, M. Jayachandran, 
Mater. Chem. Phys. 77, 397 (2002). 
 


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Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide Polycrystalline Thin Film

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