Using a modified Gaussian approximation to the depth distribution of the energy dissipation function for electron bombardment, an analytical expression was derived for electron‐beam‐induced current (EBIC) at a Schottky barrier parallel to the bombarded surface. Comparison of theory and experiment for the voltage dependence of EBIC for 14 specimens (includingp‐ andn‐type GaAs and Si) provided values for the diffusion length of excess carriers, the thickness of the metal layer of the Schottky barrier diode, and the average energyErequired to generate a hole‐electron pair. Diffusion lengths ranging from 0.41 to 55 &mgr; were determined with an estimated accuracy of ±20&percent;. The values ofEwere found to be 3.75±0.11 eV for Si and 4.68±0.14 eV for GaAs. The unique advantages of this method for measuring small diffusion lengths are emphasized.