AVS 60th International Symposium and Exhibition
    Spectroscopic Ellipsometry Focus Topic Thursday Sessions
       Session EL+AS+EN+PS+SS+TF-ThM

Invited Paper EL+AS+EN+PS+SS+TF-ThM1
Application of Spectroscopic Ellipsometry for the Characterization of Various Solar Cell Devices

Thursday, October 31, 2013, 8:00 am, Room 101 A

Session: Spectroscopic Ellipsometry for Photovoltaics and Instrument Development
Presenter: H. Fujiwara, Gifu University, Japan
Correspondent: Click to Email

To establish new structural characterization methods for Si-based and CuInGaSe2(CIGS)-based solar cells, we have developed spectroscopic ellipsometry (SE) techniques that can be applied for the analysis of various textured structures used in the solar cell devices. In particular, our SE analyses allow the structural characterization of (i) hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (μc-Si:H) tandem-type solar cells, and (ii) a-Si:H/crystalline Si (c-Si) heterojunction solar cells, both fabricated on textured substrates. For the determination of a-Si:H and μc-Si:H properties, optical databases in which the optical constants of a-Si:H and μc-Si:H are described by micro-structural factors have been constructed.1,2) Furthermore, by developing a new optical model, we have confirmed that the high-precision analysis of a-Si:H/μc-Si:H multilayer stacks can be performed even on textured substrates having sub-micron size rough surface. On the other hand, to determine the thickness and properties of a-Si:H layers incorporated into textured a-Si:H/c-Si solar cells, SE with a tilt angle measurement configuration3,4) has been employed. In this technique, samples are tilted so that the specular light reflection on the texture facets is measured. From this technique, we have succeeded in characterizing the properties of quite thin a-Si:H layers (5 nm) on the c-Si textures. Recently, we have applied the SE technique further to establish the structural characterization method for CIGS-based solar cells.5) For the SE analysis, we have constructed an optical database in which the CIGS dielectric function can be calculated as functions of the Ga composition x=Ga/(In+Ga) and Cu composition y=Cu/(In+Ga). By using the constructed optical database, we have demonstrated that the structure and compositions of CIGS-based thin films can be determined accurately.

1) Kageyama et al., Phys. Rev. B 83, 195205 (2011), 2) Yuguchi et al., J. Appl. Phys. 111, 083509 (2012), 3) Saenger et al., Thin Solid Films 518, 1830 (2010), 4) Watanabe et al., Appl. Phys. Express 3, 116604 (2010), 5) Minoura et al. J. Appl. Phys. 113, 063505 (2013).