指導老師：林克默副教授學生：陳信誠學號： m9710246 ...

太陽能材料與模組製造實驗室

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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

Low-temperature growth of highly crystallized transparent conductive fluorine-doped tin oxide films by intermittent spray pyrolysis deposition

Tatsuo Fukano, Tomoyoshi Motohiro

Solar Energy Materials & Solar Cells 82 (2004) 567–575

Toyota Central Research and Development Laboratories Inc., Nagakute, Aichi 480-1192, Japan


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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

Spraying

Heating

Measurement and analysis

2 hr. Ultrasonic agitation for 10 min

air

~340℃325–330℃


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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 heattreatment.

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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G. Haacke, J. Appl. Phys. 47 (1976) 4086

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.

The F/Sn value of 0.0074 means that the F-ion density is ~2.0 ×1020 cm-3


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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, as-

deposited 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!

指導 老師 ：林克默 副教授 學生：陳信誠 學號： m9710246 ...

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指導老師：林克默副教授學生：陳信誠學號： m9710246 ...