Investigation of minority-carrier diffusion lengths by means of the scanning electron microprobe (SEM)

Using a Gaussian approximation for the depth distribution of the energy dissipation function for electron bombardment, the electron beam induced barrier current (BC) is determined as a function of the position on a surface perpendicular to the barrier. Comparison of theory and experiment for the energy and position dependence of BC provided values for the diffusion length and the surface recombination velocity of excess carriers. The experiments are performed in a wide range of diffusion lengths and dopand concentration on Si and GaP for primary energies of electrons between 10 and 30 keV. The parameters for the Gaussian depth distribution are estimated for Si and GaP and compared with values taken from the literature.