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Low-temperature growth of highly crystallized
transparent conductive fluorine-doped tin oxide
films by intermittent spray pyrolysis deposition
Tatsuo Fukano, Tomoyoshi Motohiro
Toyota Central Research and Development Laboratories Inc., Nagakute,
Aichi 480-1192, Japan
Solar Energy Materials & Solar Cells 82 (2004) 567–575
指導老師：林克默 副教授
學生：陳信誠
學號：m9710246
班級：碩機械一甲
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大綱
 摘要
 前言
 實驗
 結果與討論
 結論
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摘要
 Following the procedure by Sawada et al. (Thin Solid
Films 409 (2002) 46), high-quality SnO2:F films were
grown on glass substrates at relatively low
temperatures of 325–340℃ by intermittent spray
pyrolysis deposition using a perfume atomizer for
cosmetics use.
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前言
 These techniques require simple apparatuses, are low
in cost but high in throughput, the necessary conditions
for commercial production of solar cells.
 Sawada et al. succeeded in producing high-quality ITO
films by spray pyrolysis at relatively low temperatures.
Highly conductive films of ITO, 1.9×10-4Ωcm in
resistivity,were fabricated on glass substrates at 350℃
using a ‘perfume atomizer’, available in cosmetics
shops.
 We will demonstrate that the SnO2:F films thus
produced are heatresistant, showing that the various
properties change little after a heat treatment.
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實驗
 The solution for SnO2:F film growth was prepared as
follows. NH4F (50m mol) was dissolved in 50 ml of
2M HCl. This mixture was diluted to 1 l with C2H5OH.
Then SnCl2 0.86H2O (0.1 mole) was dissolved into the
mixture.
 Sprayed the solution in air with the use of a perfume
atomizer on Corning #7059 glass substrates
(20×30×0.5mm3 in size),cleaned ultrasonically in
organic solvents.
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實驗
NH4F
HCl
C2H5OH
SnCl2 ． 0.86H2O
2 hr. Ultrasonic agitation for 10 min
air
Spraying
Heating
~340℃
325–330℃
Measurement
and analysis
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結果與討論





X-ray diffraction
XPS and EDX
UV-VIS-NIR
FE-SEM
Hall
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XRD
Fig. 1. XRD patterns of as-prepared SnO2:F
films of various thicknesses. Standard
powder peak intensities derived from the
JCPDS file [22] are shown in the bottom
diagram as vertical bars for single phase
SnO2 rutile.
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Fig. 2. XRD patterns of 420nm thick
SnO2:F films on the glass substrate
before and after the heat
treatment.
450℃-60min
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XPS and EDX
 We confirmed the presence of Sn, O, F and Cl in the 420
nm-thick SnO2:F film by XPS. Before the heat treatment,
the F/Sn, O/Sn and Cl/Sn atomic ratios on the film surface
were approximately 0.0074, 1.75 and 0.0033, respectively.
The F/Sn ratio is surprisingly low when compared with the
value (=0.5) in the solution. One may suspect that the film
surface is depleted of F since the detection depth of the
XPS is only 3 nm. However, an EDX investigation, with a
300nm detection depth, supported this low F concentration
throughout the film. After the heat treatment, the atomic
ratios changed to F/Sn=0.0067, O/Sn=1.66, and
Cl/Sn=0.0005. The Cl/Sn ratio was slightly decreased, but
the F/Sn and O/Sn ratios were virtually unaffected.
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UV
Fig. 3. Optical transmittance spectrum of
420nm thick SnO2:F film on the glass
substrate before and after the heat
treatment.
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FE-SEM
Fig. 4. FE-SEM images of (a) the surface morphology and (b) cross-sectional
image of SnO2:F film before the heat treatment.
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Hall
Fig. 5. Electrical properties of the SnO2:F films on the substrate for different
thickness before heattreatment. ●: resistivity, ■ : carrier density, ◇ : Hall mobility.
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The F/Sn value of 0.0074 means that the F-ion density is ~2.0 ×1020 cm-3
Haacke
ΦTC=T10 / Rsh
ΦTC–Ts
We find ΦTC=0.031 (Ω/sq.)-1 for our 420-nm-thick SnO2:F films using the
sheet resistance of 14.0Ω/sq.
G. Haacke, J. Appl. Phys. 47 (1976) 4086
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Fig. 6. Figure of merits for SnO2:F films fabricated in this work (●), and the previous
works (○) in which SnO2:F films fabricated at relatively low synthesis temperature were
obtained by spray pyrolysis depositions [1–5, 8, 9, 11, 12, 14, 15] as a function of
synthesis temperature. A numeric symbol at the side of each datum point shows a
reference number.
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結論
 Even though the substrate temperature is low, asdeposited films show a high optical transmittance of
92% in the visible range, a low electric resistivity of
5.8×10-4Ωcm and a high Hall mobility of 28 cm2/V s.
The F/Sn atomic ratio (0.0074) in the films is low in
comparison with the value (0.5) in the sprayed
solution.
 The carrier density in the film is approximately equal
to the F-ion density, suggesting that most of the F-ions
effectively function as active dopants.
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 They are quite heat resistant, showing little change in
transmittance and resistivity during a 450℃–60 min
heat treatment in the atmosphere. The obtained films
break the ΦTC–Ts limit achieved by the previous films.
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Thanks for your attention!
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