Origin of vacancy and interstitial stabilization at the amorphous-crystalline Si interface

The relative stability of neutral vacancies and interstitials in the vicinity of the amorphous-crystalline (a-c) Si interface was investigated using density-functional theory (DFT) calculations. A continuous random network (CRN) model was used in the construction of defect-free a-c interface structure. The vacancy stabilization in amorphous Si was found due to strain relief provided to the silicon lattice by the vacancy and interstitial stabilization was due to bond rearrangement associated with interstitial integration into the substrate lattice. The effect of the spongelike behavior of the amorphous phase toward native defects on ultrashallow junction formation in the fabrication of ever-shrinking electronic devices was also investigated.