Comparison of photocurrent spectra measured by FTPS and CPM for amorphous silicon layers and solar cells

• Published in: Journal of non-crystalline solids Vol. 354; no. 19-25; pp. 2167 - 2170
• Main Authors: Holovský, J., Poruba, A., Purkrt, A., Remeš, Z., Vaněček, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2008; Elsevier
• Subjects: Absorption; Applied sciences; Band structure; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Defects; Energy; Exact sciences and technology; FTIR measurements; Medium-range order; Natural energy; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Optical spectroscopy; Photoconductivity; Photovoltaic conversion; Physics; Silicon; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Solar cells; 78.20.−e; Band structure; Optical spectroscopy; Absorption; FTIR measurements; Optical properties; Silicon; Photoconductivity; Medium-range order; Defects; Defect density; Interference fringe; Medium range order; 78.20.-e; Photocurrents; Amorphous state; Absorption coefficients; Thin films; Fourier transform spectra; Urbach rule; Silicon; Solar cells; Band structure; Defects; Optical properties; Absorption; Optical spectroscopy; FTIR measurements; Photoconductivity; Defects; Medium-range order; Microcrystal
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2007.09.106

Fourier Transform Photocurrent Spectroscopy (FTPS) has been recently introduced as a fast and highly sensitive method for the evaluation of the optical absorption coefficient of photoconductive thin films such as microcrystalline silicon layers. This contribution represents the first study of FTPS utilization for amorphous silicon layers and cells. FTPS spectra are compared with results of Constant Photocurrent Method (CPM) and Dual Beam Photoconductivity (DBP) measured at different chopping frequencies. We will concentrate to highlight the appropriate measuring conditions and evaluation procedures for correct data interpretation. Moreover, we will present our novel approach for the interference free determination of absorption coefficients of thin films grown on transparent substrates, which is mainly important for very thin layers where broad interference fringes do not allow correct evaluation of parameters such as a slope of the Urbach tail and the defect density.