A Pyrosol Technique to Deposit Highly Transparent, Low‐Resistance SnO2 : F Thin Films from Dimethyltin Dichloride

Highly transparent, low‐resistance films suitable as a substrate material for thin film CdS/CdTe solar cells have been developed on 10 × 10 cm glass substrates by an ultrasonic spray pyrolysis (pyrosol) technique using dimethyltin dichloride (DMTDC) as a tin source. DMTDC, , and HF, all dissolved in water, served as the source solution. An ultrasonic vibrator operated at 1.5 MHz produced a fine spray of the source solution. It was transported, using air as a carrier gas, to moving glass plates in a belt furnace maintained at 530°C. A very high growth rate of nearly 100 Å/s was realized in this process with good homogenity, high transparency, and low resistivity. Films with a sheet resistance of less than 10 Ω/□ have been routinely prepared and their preparation technology has been well established. A proper nozzle design and exhaust system to remove the spent gases determines the technology of obtaining spot and cloud free homogeneous films in the belt furnace. A film of 5000 Å thickness exhibited the lowest electrical resistivity, of , a mobility value of , and a donor concentration of . Films of 5000–6000 Å thickness having an average transmittance of nearly 85% in the visible range and a sheet resistance of around 8 Ω/□ were used as transparent conducting oxide film substrates to fabricate thin film CdS/CdTe solar cells. A solar energy conversion efficiency of over 14% was achieved. © 1999 The Electrochemical Society. All rights reserved.