Abstract
A three-dimensional model is given for cathodoluminescence (CL) contrast from localised semiconductor defects. Electron-solid interaction is modelled by a Monte Carlo method and defects are represented by regions of enhanced non-radiative recombination. Optical losses are also taken into account. Differences in the image profiles of localised bulk defects and dislocations which intersect the top surface barrier perpendicularly suggest a method for differentiating between the two types of imperfections. A technique for determining the depth of a subsurface defect is also illustrated.