This work shows how the surface potential instabilities observed during uleSIMS profiling of various semiconductor and semi-insulating materials can be overcome by using coincident bombardment with laser light to excite electron-hole pairs. We show that the causes of the problem differ according to the material system, and may sometimes be due to the material alone, or to the interaction between the material and the primary ion beam. In some cases (e.g. Si1-xGex, phosphorus implanted silicon) it is sufficient to irradiate the SIMS crater with a photon flux density above some threshold determined by the primary ion current. In others, the laser irradiation pattern must be tailored so as to create a conducting path from the crater to the sample holder. (c) 2006 Elsevier B.V. All rights reserved.