2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/18407Defects ~10 nm in size, with number densities ~10^{10} cm^{-2}, form spontaneously beneath ion-milled, etched, or HF-dipped silicon surfaces examined in our Ti-ion getter-pumped transmission electron microscope (TEM) after exposure to air. They appear as weakly-strained non-crystalline intrusions into silicon bulk, that show up best in the TEM under conditions of strong edge or bend contrast. If ambient air exposure is <10 minutes, defect nucleation and growth can be monitored {\em in situ}. Possible mechanisms of formation are discussed.4 pages, 5 figures, RevTeX4Materials ScienceChemical Physicstext