For performing electron-beam-induced current (EBIC) measurements on sufficiently large samples, the use of a ‘‘planar-collector geometry’’ (i.e., with the collector covering part of the irradiated surface itself) is very attractive. However, the pertinent theoretical EBIC curves for finite surface-recombination velocities s have so far been lacking. This paper presents the complete theoretical expressions for arbitrary values of s and diffusion length L. Simple asymptotic solutions are given for point- and finite-size generation sources. Easy methods are developed to facilitate the application of these solutions in the practical evaluation of L and s from experimental EBIC curves. These methods are applied to experimental data available through the literature.