Minority‐carrier diffusion lengths have been measured in electron‐beam‐induced current experiments with the electron beam of the scanning electron microscope both parallel and perpendicular to a Schottky barrier on single‐crystal silicon. Results from the two geometries are compared. The usefulness of the top surface geometry (beam perpendicular to the barrier) has been extended by measuring both the short‐circuit current and its derivative as a function of position, allowing the diffusion length to be calculated without knowing the exact position of the Schottky‐barrier edge. This is particularly useful when the barrier edge is indistinct, as often occurs for evaporated or sputtered barrier layers. Measurement of the derivative signal has been accomplished by position modulation of the scanning electron beam combined with a lock‐in amplifier for signal detection.