The effect of silicon-on-insulator (SOI) substrate type and surface silicon thickness on extended defect evolution due to silicon ion implantation has been investigated. Nonamorphizing silicon implants ranging from 15 to 48.5 keV, 1 x 10(14) cm(-2), were performed into SOITEC and separation by implantation of oxygen (SIMOX) wafers. Subsequently, furnace anneals were performed at 750degreesC in an inert ambient. Quantitative transmission electron microscopy was used to measure the trapped interstitial concentration, defect density, and defect size. The type of surface silicon/buried oxide interface (e.g., SIMOX or SOITEC) does not appear to affect the decay of the trapped interstitial population or the evolution of the defect microstructure. However, the thickness of the surface silicon/BOX interface strongly affects the evolution of {311} defects, as well as the decay of trapped interstitials. The interface appears to promote formation of dislocation loops as the trapped interstitial population evolves. (C) 2004 The Electrochemical Society.