CUPROUS OXIDE THIN FILM PREPARED BY SOL GEL SPIN COATING TECHNIQUE by benbenzhou

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									CUPROUS OXIDE THIN FILM PREPARED
BY SOL-GEL SPIN COATING TECHNIQUE


           RESEARCHERS:
  IBRAHIM ABU TALIB, ABDUL RAZAK
   DAUD, MUHD. AZMI ABDUL HAMID
            PhD STUDENT:
     DEWI SURIYANI BT CHE HALIN

          Kuliah Tamu –Universitas Indonesia 29 Dec 2009
              OUTLINE

INTRODUCTION
EXPERIMENTAL
SOME RESULTS AND DISCUSSION
CONCLUSIONS



      Kuliah Tamu –Universitas Indonesia 29 Dec 2009
          INTRODUCTION
Copper forms two well known oxides;
             (1) Cu2O
             (2) CuO
Cu2O - an interesting p-type semiconductor.
     - direct optical energy band gap of 2.0-2.2 eV.
     - nontoxic and lower cost to produce.
     - cubic structure with a lattice parameter of
       4.27 Å.

           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
Cu2O - a promising material in solar energy
applications.

Various methods have been used to prepare
Cu2O thin films;
             Sputtering
             Thermal oxidation
             Electrodeposition
             Vacuum evaporation
             Sol-gel technique

           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
Sol-gel spin coating requires considerably;
             Less equipment
             Low cost production

Sol-gel is a soft bottom-up approach to achieve a good
control over film composition and microstructure.




             Kuliah Tamu –Universitas Indonesia 29 Dec 2009
            SAMPLE PREPARATION
Copper (II) acetate        Isopropyl alcohol          Diethanolamine (DEA)


                          Mixed continuously

                                                                2 types of additives:
                      Add small amount of glucopone
                                                                1)Polyethylene glycol
                                                                2)Ethylene glycol
              Stirring using magnetic bar for 24 hours

                      Filtered using 0.45 μm filter

                      Spin coating (2-6 krpm, 40s)
                                                            Repeated for 3 layers
                                                                of coating
                      Dried in oven (60 ˚C, 10 min)

                        Annealing (350-550 ˚C)              5% H2 95% N2

                          Cuprous oxide films

              Kuliah Tamu –Universitas Indonesia 29 Dec 2009
           CHARACTERIZATION

• XRD (Bruker D8 Advance XRD, Cu Kα2, λ = 1.5406
  Å) – phase and structure

• SEM ( LEO 1450 VP) - Surface morphology.

• UV-VIS (Perkin Elmer Lambda 900) - Optical
  reflectance




            Kuliah Tamu –Universitas Indonesia 29 Dec 2009
           SOME RESULTS

     1. EFFECT OF ANNEALING
           TEMPERATURE

Films were prepared at spinning rate 3000 rpm for 40 s




           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
                                                  XRD
 )
 ( a . u                                                                  XRD of film with
                O C ( u1 1 1 )                                            parameters: 2000 rpm,
 s i t y

                2

                                                                          40 s, annealed at 350 oC
                             O C ( u2 0 0 )
                             2
                                                            550oC o
                                                          5 5 0   C
                                                                          in 5% H2 95% N2
 t e n




                                                            450oC
 I n




                                                                  o
                                                          4 5 0   C




                                                            350oC
                                                          3 5 0   o
                                                                  C




   0       2        0    3                0   4   0   5           0   6

               r e e )       e g   (2 d


mineral cuprite,Cu2O (JCPDs card no. 01-075-1531).
cubic cuprous oxide having more pronounced
crystallinity at higher annealing temperature
                             Kuliah Tamu –Universitas Indonesia 29 Dec 2009
                           MORPHOLOGY
          (a)
          350 oC                    (b)
                                    450 oC




   Irregular shapes with   (c)
                           550 oC                     The grain coverage is
   average size of 100                                more conformal
   nm                                                 compared to sample
                                                      annealed at 350 °C
• Rectangular like                                    and 550 °C.
  shape with average
  size of 200 nm.
• The small grains
  coalesce with each
  other to form larger
  grains.                             Kuliah Tamu –Universitas Indonesia 29 Dec 2009
     )
     ( %
     e f l e c t a n c e
 0   0                     1
                                                 o
                                                                                                     450 oC
                                   3 5 0         C
              0            9
                                                 o
                                   4 5 0         C
                                                 o
              0            8       5 5 0         C

              0            7                                                                         550 oC
              0            6
     R




              0            5


              0            4
                                                                                                     350 oC
              0            3


      2 0
       0 0                     4     0   5   4       0   0   5   0   5   5   0   0   6   0   5   6

a v e l e n g t h ,                                      W           n m




 The variation of maximum reflectance is
 believed to be influenced by grain size, shape and
 coverage of samples.

                                             Kuliah Tamu –Universitas Indonesia 29 Dec 2009
The reduce reflectance below 450 nm for all
samples may contribute
         to absorption by Cu2O since the
    energy gap of cuprous oxide is reported at
    2.0- 2.2 eV.
         scattering of grain size and shape.




          Kuliah Tamu –Universitas Indonesia 29 Dec 2009
   2. EFFECT OF SPINNING RATE

Films were annealed at 350 oC for 40 s in 5% H2 95% N2




           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
                              MORPHOLOGY
               (a)                            (b)




2000 rpm -                     (c)                                     4000 rpm –
grain size ~ 61 nm,
                                                                       grain size ~ 49 nm,
thickness ~ 108 nm.
                                                                       thickness ~ 64 nm.

                                                                6000 rpm –
                                                                grain size ~ 45 nm,
                                                                thickness ~ 102 nm.

  • Fine grains of rounded shapes with average size lower as
    spinning rate is higher

  Source: D. S. C. Halin, I. A. Talib, A. R. Daud, M. A. A. Hamid. (2009). Solid State Science
  and Technology 17(1): 119-125.
         ( a .
         b s o r b a n c e                   OPTICAL ABSORBANCE

                             4                                                            The lowest spin rate
                                                                                        produced the the
                             3
                                                                                        highest absorbance

                             2
 r p m                       2 0 0 0
         A




   6 0 0 0 4 0 p0 m 1 r p m
             r     0



              0
    0      0 3 0                 0     0 4   0   0 5   0   0 6   0   0 7   0   8
a v e l e n g t                              )W        ( n m

    Source: D. S. C. Halin*, I. A. Talib, A. R. Daud, M. A. A. Hamid. (2009). Solid State
    Science and Technology 17(1): 119-125.

                                                  Kuliah Tamu –Universitas Indonesia 29 Dec 2009
                     EFFECT OF SPIN RATE

Spinning rate             Grain size              Thickness              Optical band
    (rpm)                   (nm)                    (nm)                  gap (eV)

      2000                      61                      108                   2.08


      4000                      52                       64                   2.16


      6000                      45                       58                   2.20

Source: D. S. C. Halin*, I. A. Talib, A. R. Daud, M. A. A. Hamid. (2009). Solid State
Science and Technology 17(1): 119-125.

                        Kuliah Tamu –Universitas Indonesia 29 Dec 2009
     3. INFLUENCE OF OF USING
             ADDITIVES

Films were annealed at 350 oC for 1 hr in 5% H2 95% N2
                    atmosphere




           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
)
                                                                                    XRD
. u
( a
s i t y



          )   1   1       ( 1
                                        )       0       0   ( 2
                                                                                                    With EG additive
  )       0   1   ( 1

                                                                  3   l e   p   m   a   S
n
t e
I n




                                                                  2   l e   p   m   a   S
                                                                                                    With PEG additive



                                                                  1   l e   p   m   a   S           Without additive

                  0       3                         0       4               0   5           0   6
              )       e       r e   g       e       ( 2d



      cubic cuprous oxide having more pronounced
      crystallinity at higher annealing temperature

                                                Kuliah Tamu –Universitas Indonesia 29 Dec 2009
                                 MORPHOLOGY
              Sample 1                           Sample 2




Without additive,              Sample 3                                       PEG additive,
grain size ~ 104 nm,                                                          grain size ~ 83 nm,
thickness ~ 102 nm.                                                           thickness ~ 395 nm.

                                                                      EG additive,
                                                                      grain size ~ 90 nm,
                                                                      thickness ~ 59 nm.
  • Fine grains of irregular shapes
  • The use of additives reduces the size of the grains
  Source: D. S. C. Halin, I. A. Talib, A. R. Daud, M. A. A. Hamid. Regional Conf. On Solid State Science
  and Technology, 21-23 Dec 2009, Penang, Malaysia.
                 )
                 ( a . u
                                                  OPTICAL ABSORBANCE
                 c e

               . 5         2
                 a n


                                                                                                                   With PEG additive,
                                                                                                                   Eg ~ 1.90 eV
                 r b




               . 0         2
                 s o




                                                                                                                   Without additive,
               . 5         1
                 b




                                                                                                                   Eg ~ 1.85 eV
                 A




               . 0         1                 2         l e     p       a m   S

                                                  1          l e   p     a m      S

               . 5         0         3           l e     p         a m   S
                                                                                                                    With EG additive,
                                                                                                                    Eg ~ 1.85 eV
               0 . 0
               0 0             0 3       0       0 4         0     0 5   0       0 6   0   0 7   0   0 8   0   9
 ,   t h   g     e l e n                     a v                   )W        m     ( n

               higher absorbance obtained by using PEG additive

Source: D. S. C. Halin, I. A. Talib, A. R. Daud, M. A. A. Hamid. Regional Conf. on Solid State Science
and Technology, Penang, 21-23 Dec 2009.
                 EFFECT OF USING ADDITIVES

    Additive                 Grain size                Thickness                        Eg
                               (nm)                      (nm)                          (eV)

       None                       104                        102                      2.08


       PEG                          83                       395                      2.16


         EG                         90                        59                      2.20

Source: D. S. C. Halin, I. A. Talib, A. R. Daud, M. A. A. Hamid. Regional Conf. on Solid State Science
and Technology, Penang, 21-23 Dec 2009.

                          Kuliah Tamu –Universitas Indonesia 29 Dec 2009
              CONCLUSIONS
• Cu2O thin films were successfully grown onto ITO
  coated glass by sol-gel spin coating using copper(II)
  acetate.
• Preparation parameters affect the structure,
  morphology and optical properties of the films.
• The evolution of microstructure and crystallinity of
  the films were increased with annealing temperature.
• Film produced using lower spinning rate was thicker
  single phase of Cu2O with cubic structure.
• The addition of polyethylene glycol enhanced the
  properties of the films, such as decreasing grain size
  increasing optical absorbance, energy gap and the
  thickness of films.
   ACKNOWLEDGEMENT
The researchers gratefully acknowledge the financial
support by MOSTI, through Science Fund grant No.
03-01-02-SF0211.

Universiti Malaysia Perlis (UniMAP) for the PhD
scholarship (Feb 2006-Feb 2010) to Dewi Suriayani.




           Kuliah Tamu –Universitas Indonesia 29 Dec 2009
THANK YOU FOR
YOUR ATTENTION


  Kuliah Tamu –Universitas Indonesia 29 Dec 2009

								
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