This presentation discusses disorder in AlGaAs unstrained systems in bulk.
- Bandstructure of an ideal simple unit cell
- What happens when there is disorder?
- Concept of a supercell
- Band folding in a supercell
- Band extraction from the concept of approximate bandstructure
- Comparison of alloy disorder with the virtual crystal approximation
- Configuration noise, concentration noise
- How large does an alloy supercell have to be? When does the “bulk” condition occur?
- Bandedges and bandgaps are influenced by:
- Placement / configuration disorder
- Concentration noise
- System size is very important
- “bulk” starts at 100,000 atoms
- => Nanostructures are not “bulk”
=> like quantum dots, nanowires, and quantum wells vary locally
Università di Pisa, Pisa, Italy