<title>Minority Carrier Diffusion Lengths And Absorption Coefficients In Silicon Sheet Material</title>

Abstract

One of the indicators which determine a material's potential for use as a solar cell is the minority carrier diffusion length (LD) of the material. To determine LD a surface photovoltage (SPV) technique is used.This method is dependent upon an accurate knowledge of the optical absorption coefficient as function of wavelength. Most of the work to date in this area has involved Czochralski grown material which has resulted in two empirical models for the absorption coefficients. However, with the advent of new growth processes, for example ribbon growth and cast silicon, it became necessary to measure the absorption coefficients of these materials before a SPV measurement could be performed.The results for the absorption coefficients for various types of silicon sheet material are compared to those previously used in the two models.The resultant effect upon the diffusion length is also discussed in detail.