The effects of hydrogen and oxygen plasma treatments on the structural properties ofn-typec-Si were examined. Specimens were exposed to either an oxygen or a hydrogen electron-cyclotron-resonance plasma in a temperature range of 240–385 °C. Hydrogenations performed at low temperatures (<300 °C) introduced platelets. On the other hand, oxygen plasma treatments did not result in the formation of platelets. Analysis of O and H concentration depth profiles, measured by secondary-ion-mass spectrometry (SIMS), reveal that O and H migrate with a similar diffusion coefficient ofDeff≈1012 cm2 s−1.Moreover, the O concentration exceeds the H concentration by roughly a factor of 2.5. This suggests that one H atom and 2–3 O atoms migrate as a cluster. Furthermore, evidence of deep traps for H and O was found from the SIMS depth profiles. ©1998 American Institute of Physics.