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"Intrinsic" acceptor ground state splitting in silicon: an isotopic effect
D Karaiskaj1, M L W Thewalt, T Ruf
1Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
Physical Review Letters
|July 5, 2002
Summary
Small splittings in silicon
Area of Science:
- Semiconductor physics
- Solid-state physics
Background:
- The neutral acceptor ground state in silicon exhibits small splittings.
- These splittings deviate from the expected fourfold-degenerate Gamma(8) symmetry state.
- The origin of these splittings has been a long-standing question in semiconductor physics.
Purpose of the Study:
- To investigate the origin of the small splittings of the neutral acceptor ground state in silicon.
- To determine if isotopic composition influences these ground state splittings.
Main Methods:
- Photoluminescence spectroscopy was performed on isotopically purified 28Si.
- Measurements focused on acceptor bound excitons in the purified silicon samples.
Main Results:
- Acceptor ground state splittings were found to be absent in the photoluminescence spectra of isotopically purified 28Si.
- This indicates that the previously observed splittings in natural silicon are not an intrinsic property.
Conclusions:
- The randomness of silicon's isotopic composition is the cause of the observed acceptor ground state splittings in natural silicon.
- This finding resolves a long-standing question regarding semiconductor physics in silicon.