Recrystallization and sulfur diffusion in CdCl2-treated CdTe/CdS thin films

✍ Scribed by B. E. McCandless; L. V. Moulton; R. W. Birkmire

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 404 KB
• Volume: 5
• Category: Article
• ISSN: 1062-7995
• DOI: 10.1002/(sici)1099-159x(199707/08)5:4<249::aid-pip178>3.0.co;2-s

✦ Synopsis

The role of CdCl 2 in prompting recrystallization, grain growth and interdiusion between CdS and CdTe layers in physical vapor-deposited CdS/CdTe thin-®lm solar cells is presented. Several CdTe/CdS thin-®lm samples with dierent CdTe ®lm thicknesses were treated in air at 4158C for dierent times with and without a surface coating of CdCl 2 . The samples were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, x-ray diractometry and optical absorption. The results show that CdCl 2 treatment enhances the recrystallization and diusion processes, leading to a compositional variation within the CdTe layer due to diusion of sulfur from the CdS. The highest sulfur concentrations observed after 30 min treatments with CdCl 2 at 4158C are near the solubility limit for sulfur in CdTe. The compositional distributions indicated by x-ray diraction measurements of samples with dierent CdTe thickness show that the S-rich CdTe 1 Àx S x region lies near the CdTe/CdS interface. A multiple-step mixing process must be inferred to account for the diraction pro®les obtained.