Table of Contents Author Guidelines Submit a Manuscript
International Journal of Photoenergy
Volume 2013, Article ID 431614, 7 pages
http://dx.doi.org/10.1155/2013/431614
Research Article

Surface Passivation and Antireflection Behavior of ALD on n-Type Silicon for Solar Cells

1Department of Materials Science and Engineering, National Dong Hwa University, Hualien 97401, Taiwan
2Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan
3Institute of Photonic System, National Chiao Tung University, Tainan 71150, Taiwan

Received 16 September 2013; Accepted 30 October 2013

Academic Editor: Jimmy Yu

Copyright © 2013 Ing-Song Yu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Atomic layer deposition, a method of excellent step coverage and conformal deposition, was used to deposit TiO2 thin films for the surface passivation and antireflection coating of silicon solar cells. TiO2 thin films deposited at different temperatures (200°C, 300°C, 400°C, and 500°C) on FZ n-type silicon wafers are in the thickness of 66.4 nm ± 1.1 nm and in the form of self-limiting growth. For the properties of surface passivation, Si surface is effectively passivated by the 200°C deposition TiO2 thin film. Its effective minority carrier lifetime, measured by the photoconductance decay method, is improved 133% at the injection level of  cm−3. Depending on different deposition parameters and annealing processes, we can control the crystallinity of TiO2 and find low-temperature TiO2 phase (anatase) better passivation performance than the high-temperature one (rutile), which is consistent with the results of work function measured by Kelvin probe. In addition, TiO2 thin films on polished Si wafer serve as good ARC layers with refractive index between 2.13 and 2.44 at 632.8 nm. Weighted average reflectance at AM1.5G reduces more than half after the deposition of TiO2. Finally, surface passivation and antireflection properties of TiO2 are stable after the cofire process of conventional crystalline Si solar cells.