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E center in silicon has a donor level in the band gap
A Nylandsted Larsen1, A Mesli, K Bonde Nielsen
1Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
Physical Review Letters
|October 10, 2006
Summary
The E center in silicon, a well-studied semiconductor defect, possesses a previously unknown donor energy level. This discovery challenges existing models of impurity diffusion in silicon.
Area of Science:
- Semiconductor Physics
- Materials Science
- Defect Engineering
Background:
- The E center (group-V impurity-vacancy pair) in silicon is a widely studied defect.
- For over 40 years, it was believed to have only one energy level within the band gap (acceptor level at ~0.45 eV below conduction band).
Purpose of the Study:
- To investigate the electronic structure of the E center in silicon.
- To determine if the E center possesses additional energy levels beyond the established acceptor level.
Main Methods:
- Utilized a combination of transient-capacitance techniques.
- Performed advanced electronic-structure calculations.
Main Results:
- Demonstrated the existence of a second energy level for the E center.
- This new level is located in the lower half of the band gap, 0.27 eV above the valence band.
- The newly identified level exhibits donor character.
Conclusions:
- The E center in silicon has a second, previously unrecognized donor energy level.
- This finding necessitates a re-evaluation of past diffusion-modeling approaches for silicon.
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