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Evidence for native-defect donors in n-type ZnO.
D C Look1, G C Farlow, Pakpoom Reunchan
1Semiconductor Research Center, Wright State University, Dayton, Ohio 45435, USA.
Physical Review Letters
|December 31, 2005
Summary
Native defects, like the zinc interstitial complexed with nitrogen, are key donors in ZnO, challenging previous theories. These native defects also act as crucial acceptors, impacting ZnO material properties.
Area of Science:
- Materials Science
- Solid State Physics
- Defect Chemistry
Background:
- Previous theoretical studies suggested native defects in n-type ZnO have high formation energies.
- Native defects were considered less significant than impurities like hydrogen (H) as donors in ZnO.
Purpose of the Study:
- To investigate the role of native defects as donors and acceptors in bulk ZnO.
- To identify the dominant donor responsible for the commonly observed 30 meV donor level in vapor-phase grown ZnO.
Main Methods:
- Combined theoretical calculations and experimental analysis.
- Investigated defect formation energies and donor/acceptor behavior under specific ambient conditions.
Main Results:
- The zinc interstitial-nitrogen on oxygen site (Zn(I)-N(O)) complex is identified as a dominant donor in ZnO under nitrogen ambient.
- This complex is a more significant donor than hydrogen (H) or other known impurities.
- The zinc vacancy (V(Zn)) is confirmed as the dominant acceptor in the studied ZnO material.
Conclusions:
- Native defects, specifically the Zn(I)-N(O) complex and V(Zn), play a critical role as both donors and acceptors in ZnO.
- Revises the understanding of defect contributions to electrical properties in ZnO.
- Highlights the importance of native defects in bulk ZnO grown from the vapor phase.