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Auger and XRD Investigations of Sulphur Diffusion at the CdS/CdTe Interface

Funded under: FP5


Diffusion of atoms across the CdS/CdTe interface during post deposition annealing is thought to have an important effect on the performance of CdS/CdTe solar cells. A series of experiments have been performed on samples that were deposited using a proprietary process and then treated to annealing cycles at 400 degrees Celsius or 450 degrees Celsius for a range of different times. The samples were sequentially etched in a bromine / methanol solution and then examined with XRD. After several chemical etching cycles, Augur depth profiling was used to determine the extent of sulphur diffusion into the CdTe. The results showed that the as-deposited samples has little or no interfacial mixing. Annealing even for a short time caused a rapid diffusion of S into the CdTe material. As the annealing times lengthened, the concentration of sulphur in the CdTe increased. The XRD measurements indicated that the CdS layer rapidly crystallized into its hexagonal Greenockite modification with a distorted unit cell. This changed little with annealing time. The CdTe near the interface appeared to have a well-defined and different structure, though still cubic, from the bulk of the CdTe, as indicated by splitting of the CdTe diffraction peaks.

Additional information

Authors: GIBSON P N, European Commission, Joint Research Centre, Ispra (IT);BAKER M A, University of Surrey, School of Mechanical and Materials Engineering, Guildford (GB);OZSAN M E, BP Solarex, 12 Brooklands Close, Windmill Road, Sunbury-on-Thames (GB)
Bibliographic Reference: Paper presented: The European Material Conference, Strasbourg (FR) 30 May - 2 June 2000
Availability: Available from European Commission, Joint Research Centre, Ispra (IT)
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