Stress-induced alignment of NL8 thermal donors in silicon: Energetics and kinetics

Abstract

Preferential alignment is produced for the NL8 thermal double donors ͑TDDs͒ when uniaxial stress is applied during their formation at ϳ450°C. The recovery kinetics reveal that they can reorient readily on the time scale of their lifetime and their individual alignments therefore reflect the strain fields that each introduces into the lattice. Analysis reveals that each of the donor cores produces large compressional strain along its C 2v ͓001͔Ј axis, the magnitude of which decreases monotonically with increase in the TDD species series, suggesting strain relief as the mechanism for nearby oxygen accumulation. The rate and activation energy for the reorientation suggests that the process is limited by the diffusion motion of the nearby interstitial oxygen atoms, with ϳ5 jumps being required for TDD3, the third in the series, and progressively more for the subsequent ones.

First-principles study of migration, restructuring, and dissociation energies of oxygen complexes in silicon

“…For e ϭ0.2 eV the migration barrier is lowered further below 0.5 eV by the charge-exchange mechanism ͓diamonds ͑0͒ → squares (ϩϩ)→ diamonds ͑0͒ in Fig. 7͔ [46][47][48] The electrically inactive staggered O 3 chain and the electrically active O i -O 2r ͑and O 2r -O i ) form a bistable system. A similar bistable system is also found experimentally for TDD0.…”

Stress-induced alignment and reorientation of hydrogen-associated donors in silicon

“…1͑b͔͒. As with the NL8, 22 the dominant effect for AA1 is the tendency for the defect to align with their g 2 ͓110͔ axis along the stress direction. However, for the AA1 center, the probability a ͑as well as b͒ is decreased in contrast to NL8, where both the a and the c probabilities are increased under ͓110͔ stress direction.…”

“…Under stress along the ͓110͔ direction, the intensities of the components provide a direct quantitative measure of defect alignment, given by A:B: Cϭa:4b:c, where a, b, c are the probabilities for each defect orientation. 22 After the creation of the AA1 spectrum ͑400°C, 20 min͒, an uniaxial stress of 200 MPa was applied to the ͓110͔ axis of the sample at 320°C for 30 min. Then the sample was cooled to room temperature in a time of ϳ60 min under stress.…”

“…This indicates that the defect is actually reoriented. Expressions for the description of recovery kinetics of defects with C 2v symmetry have previously been established 22 and were used for analysis of the recovery process of the AA1 center:…”

“…We now report the investigation results of the stress-induced alignment of the AA1 center, together with recovery data and compare them with the corresponding measurements for NL8. 22 shown that the spectra relate to two different defects.…”