Theoretical characterization of silicon self-interstitial clusters in uniform strain fields

We use first-principles density-functional theory calculations to evaluate the orientation-dependent stability of small, neutral self-interstitial clusters (I-n, n <= 4) in crystalline Si across a range of uniform strain conditions (-4 <=epsilon <= 4%) in both uniaxial and biaxial strain fields on Si(100). Comprehending the behavior of these small clusters under strain is important in extending our understanding of the evolutionary cycle of interstitial defects during the ion implantation and annealing processes that occur during semiconductor manufacturing. Our calculation results suggest that strain of sufficient magnitude can contribute to significant ground-state structural distortion and even generation of different cluster configurations. Our study also indicates that the relative stability change per unit change in applied strain is greater in the biaxial case than the uniaxial case for interstitial clusters. We provide localized strain-distribution profiles and modification of bulk Si density of states to characterize the extent to which interstitial clusters modulate crystalline Si structure.