Hole states in vertically coupled double Ge/Si quantum dots

✍ Scribed by A.I. Yakimov; A.A. Bloshkin; A.I. Nikiforov; A.V. Dvurechenskii

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 428 KB
• Volume: 40
• Category: Article
• ISSN: 0026-2692
• DOI: 10.1016/j.mejo.2008.11.015

✦ Synopsis

Using a six-band k Á p formalism we investigated the single-particle hole states in the double quantum dots made of two identical, vertically stacked, Ge/Si nanoclusters. The elastic strain due to the lattice mismatch between Ge and Si was included into the problem via Bir-Pikus Hamiltonian. As consequence of inhomogeneous strain distribution, the symmetry of states is breaking. The splitting of bonding state, s S , from antibonding one, s AS , is not symmetric, the average hole binding energy decreases with decreasing interdot separation. The change of interdot separation t Si causes crossing between the energy levels corresponding to s S and s AS orbitals. As a result, at t Si \4 nm, the antibonding state s AS becomes the ground state of the system, replacing the s S state.