Mg doping affects dislocation core structures in GaN.
S K Rhode1, M K Horton, M J Kappers
1Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, United Kingdom. sr583@cam.ac.uk
Physical Review Letters
|July 30, 2013
Summary
Magnesium doping in gallium nitride (GaN) films prevents the dissociation of (a+c)-type dislocations, stabilizing their core structures. This finding highlights the significant impact of Mg on GaN dislocation behavior.
Area of Science:
- Materials Science
- Solid State Physics
- Semiconductor Research
Background:
- Threading dislocations significantly impact the electronic and optical properties of gallium nitride (GaN) films.
- Understanding dislocation core structures is crucial for optimizing GaN-based device performance.
- Both undoped and Mg-doped GaN films with varying dislocation densities were examined.
Purpose of the Study:
- To investigate the core structures of threading dislocations in undoped and Mg-doped GaN films.
- To determine the influence of Mg doping on dislocation behavior and core stability.
- To elucidate the mechanisms of dislocation dissociation in GaN.
Main Methods:
- Aberration-corrected scanning transmission electron microscopy (AC-STEM) was employed.
- High and low dislocation density undoped GaN films were analyzed.
- A high dislocation density Mg-doped GaN film was investigated for comparison.
Main Results:
- All investigated a-type dislocations exhibited a consistent 5/7-atom core structure.
- In undoped GaN, (a+c)-type dislocations frequently dissociated due to local strain.
- Mg doping effectively suppressed the dissociation of (a+c)-type dislocations in GaN.
Conclusions:
- Mg doping plays a critical role in stabilizing dislocation cores in GaN.
- The observed suppression of dissociation suggests Mg atoms interact with dislocation cores.
- These findings offer insights into defect engineering for improved GaN material quality.
