EBIC diffusion length evaluation by the moment method

The diffusion length of minority carriers in n-type Fz Si is obtained with the electron beam induced current (EBIC) technique in planar configuration. The charge collection current as a function of the beam-junction distance is analysed by the moment method, which is based on the calculation of the variance of the derivative of the current profile. This method requires no assumptions on the surface recombination velocity and, thus, provides a diffusion length evaluation free from its influence. The data are also analysed with the asymptotic method, which requires conventional assumptions on the surface recombination velocity.