Effect of ZnO buffer layer on AZO film properties and photovoltaic applications

• Published in: Journal of materials science. Materials in electronics Vol. 21; no. 10; pp. 1005 - 1013
• Main Authors: Shi, J. H., Huang, S. M., Chu, J. B., Zhu, H. B., Wang, Z. A., Li, X. D., Zhang, D. W., Sun, Z., Cheng, W. J., Huang, F. Q., Yin, X. J.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-10-2010; Springer; Springer Nature B.V
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electronics; Energy; Exact sciences and technology; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Optical and Electronic Materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Optoelectronic devices; Photovoltaic conversion; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar cells. Photoelectrochemical cells; Solar energy; Copper Indium Gallium Selenide; Antireflective Film; Hall Mobility; Transparent Conductive Oxide; Thin Film Solar Cell; Photovoltaic effects; Electrical conductivity; Indium selenides; Hall mobility; Glass; Optimization; Thin films; Cathode sputtering; Transparent thin film; Microelectronic fabrication; Manufacturing processes; Lining processes; Ambient temperature; Optical properties; Optical characteristic; Zinc oxide; Argon; Cost lowering; Radiofrequency sputtering; Electrical characteristic; Solar cells; Buffer layer; Electrical properties; Doped materials; Radiofrequency; Cadmium sulfide; RF systems; Conducting materials; Thickness; Copper selenides; Aluminium additions; Sputter deposition; Carrier density; Transparent material; Gallium selenides
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-009-0028-8

Aluminum-doped ZnO (AZO) transparent conducting films were deposited on glass substrates with and without intrinsic ZnO (i-ZnO) buffer layers by a home made and low cost radio-frequency (RF) magnetron sputtering system at room temperature in pure argon ambient and under a low vacuum level. The films were examined and characterized for electrical, optical, and structural properties for the application of CIGS solar cells. The influence of sputter power, deposition pressure, film thickness and residual pressure on electrical and optical properties of layered films of AZO, i-ZnO and AZO/i-ZnO was investigated. The optimization of coating process parameters (RF power, sputtering pressure, thickness) was carried out. The effects of i-ZnO buffer layer on AZO films were investigated. By inserting thin i-ZnO layers with a thickness not greater than 125 nm under the AZO layers, both the carrier concentration and Hall mobility were increased. The resistivity of these layered films was lower than that of single layered AZO films. The related mechanisms and plasma physics were discussed. Copper indium gallium selenide (CIGS) thin film solar cells were fabricated by incorporating bi-layer ZnO films on CdS/CIGS/Mo/glass substrates. Efficiencies of the order of 7–8% were achieved for the manufactured CIGS solar cells (4–5 cm
2
in size) without antireflective films. The results demonstrated that RF sputtered layered AZO/i-ZnO films are suitable for application in low cost CIGS solar cells as transparent conductive electrodes.