We report on measurements of the potential profile of a GaAs/AlGaAsn‐i‐p‐imultiple quantum well structure using a scanning Kelvin probe force microscope (KFM). Using this novel technique we directly measure with meV precision and sub‐100 nm spatial resolution the potential difference betweenn‐i‐p‐ilayers with and without external optical excitation. The measured potential profiles, which have not been directly imaged previously, agree well with potential profiles calculated for optically excitedn‐i‐p‐istructures, but modified by band bending effects at the surface. ©1995 American Institute of Physics.