Iodine Doping of CdTe and CdMgTe for Photovoltaic Applications

• Published in: Journal of electronic materials 2017-09, Vol.46 (9), p.5424-5429
• Main Authors: Ogedengbe, O. S., Swartz, C. H., Jayathilaka, P. A. R. D., Petersen, J. E., Sohal, S., LeBlanc, E. G., Edirisooriya, M., Zaunbrecher, K. N., Wang, A., Barnes, T. M., Myers, T. H.
• Format: Article
• Language: English
• Subjects: Activation energy; Cadmium telluride; Cadmium tellurides; Carrier density; Cd1-xMgxTe; CdTe; Characterization and Evaluation of Materials; Chemistry and Materials Science; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Dopants; Doping; Electronics and Microelectronics; Epitaxial growth; Hall effect; Indium; Instrumentation; Iodine; Mass spectrometry; Materials Science; MBE; Molecular beam epitaxy; Optical and Electronic Materials; Optical properties; Photoluminescence; Photovoltaic cells; Radiative recombination; Secondary ion mass spectrometry; solar cell; SOLAR ENERGY; Solid State Physics; Thermal stability
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-017-5588-4

Iodine-doped CdTe and Cd 1− x Mg x Te layers were grown by molecular beam epitaxy. Secondary ion mass spectrometry characterization was used to measure dopant concentration, while Hall measurement was used for determining carrier concentration. Photoluminescence intensity and time-resolved photoluminescence techniques were used for optical characterization. Maximum n -typ e carrier concentrations of 7.4 × 10 18  cm −3 for CdTe and 3 × 10 17  cm −3 for Cd 0.65 Mg 0.35 Te were achieved. Studies suggest that electrically active doping with iodine is limited with dopant concentration much above these values. Dopant activation of about 80% was observed in most of the CdTe samples. The estimated activation energy is about 6 meV for CdTe and the value for Cd 0.65 Mg 0.35 Te is about 58 meV. Iodine-doped samples exhibit long lifetimes with no evidence of photoluminescence degradation with doping as high as 2 × 10 18  cm −3 , while indium shows substantial non-radiative recombination at carrier concentrations above 5 × 10 16  cm −3 . Iodine was shown to be thermally stable in CdTe at temperatures up to 600°C. Results suggest iodine may be a preferred n -type dopant compared to indium in achieving heavily doped n -type CdTe.