Optimization of depth resolution in secondary ion mass spectrometry (SIMS) depth profiling has been carried out prior to characterization of different nanoscale semiconductor devices based on Si, GaAs and SiGe. The optimization of depth resolution was carried out by adjusting different experimental parameters like primary ion beam energy, ion mass, angle of incidence, sputter rate, etc. Such adjustments control the basic processes like recoil mixing, cascade mixing or penetration depth which in turn control the depth resolution Deltaz. Certified reference material Ta2O5/Ta was used as standard to optimize the parameters and the actual experiments were performed keeping them in view. Various nanoscale semiconductor devices were characterized for their interfaces, e.g.: 1. InP/InGaAs/InP. . . quantum well (QW) structures. 2. SixNy/n-GaAs structures with NH3 plasma pre-treatment of GaAs for MIS devices. 3. Ga2O3(Gd2O3)/Si0.74Ge0.26/Si structures for MIS devices. 4. Ga2O3(Gd2O3)/GaAs structures for MOS devices. 5. Au/GaN/Si schottky diodes. 6. Ge/Si bilayer films for swift heavy ion beam induced interface-mixing experiment. It has been observed that Cs+ primary ion beam with 10-11 keV energy gives Deltaz similar to2-3 nm for most of the depth profiles while O-2(+) with 7 keV energy can also give Deltaz of similar order (similar to2 nm) in some of the systems depending on ion-matrix interaction and secondary ion yield response. (C) 2003 Published by Elsevier B.V.