Boron-doped zinc oxide thin films for large-area solar cells grown by metal organic chemical vapor deposition

• Published in: Thin solid films 2007-02, Vol.515 (7), p.3753-3759
• Main Authors: Chen, X.L., Xu, B.H., Xue, J.M., Zhao, Y., Wei, C.C., Sun, J., Wang, Y., Zhang, X.D., Geng, X.H.
• Format: Article
• Language: English
• Subjects: Boron-doping; Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Single-crystal and powder diffraction; Solar cells; Structure of solids and liquids; crystallography; X-ray diffraction and scattering; Zinc oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2006.09.039

Boron-doped zinc oxide (ZnO:B) films were grown by metal organic chemical vapor deposition using diethylzinc (DEZn), and H 2O as reactant gases and diborane (B 2H 6) as an n-type dopant gas. The structural, electrical and optical properties of ZnO films doped at different B 2H 6 flow rates were investigated. X-ray diffraction spectra and scanning electron microscopy images indicate that boron-doping plays an important role on the microstructure of ZnO films, which induced textured morphology. With optimized conditions, low sheet resistance (∼ 30 Ω/□), high transparency (> 85% in the visible light and infrared range) and high mobility (17.8 cm 2 V − 1 s − 1 ) were obtained for 700-nm ZnO:B films deposited on 20 cm × 20 cm glass substrates at the temperature of 443 K. After long-term exposure in air, the ZnO:B films also showed a better electrical stability than the un-doped samples. With the application of ZnO:B/Al back contacts, the short circuit current density was effectively enhanced by about 3 mA/cm 2 for a small area a-Si:H cell and a high efficiency of 9.1% was obtained for a large-area (20 cm × 20 cm) a-Si solar module.