O. Marquardt, T. Hickel and J. Neugebauer
Motivation
The investigation of the optoelectronic properties of semiconductor nanostructures like quantum dots, wires and wells is required i.e. for the development of new light sources.
Our aim is to predict the optoelectronic properties of experimentally interesting nanostructures as well as to design nanostructures which meet the requirements of one particular application. Furthermore, the choice of a continuum approach with the computational effort being independent from the number of involved atoms makes a comparison to more accurate but more expensive atomistic methods necessary.
Method
In order to calculate the electronic structure of a given semiconductor nanostructure, we chose the continuum 8-band k*p formalism. Strain and polarization effects arising from lattice mismatch and spontaneous polarization are calculated from continuum elasticity theory. These two real-space models have been implemented in our plane-wave library S/PHI/nX which allows us to use the highly optimized minimization routines as well as the self-consistent methods available in plane-wave codes.
To verify the validity of our approach, a comparison to atomistic tight-binding and effective bond-orbital models has been performed for a relatively small GaN/AlN quantum dot, including the investigation of less sophisticated k*p and effective mass models [1]. The results from the eight-band k*p model are in perfect agreement with the atomistic calculations.
[1]: Marquardt, Mourad, Schulz, Hickel, Czycholl, Neugebauer: Phys. Rev. B 78, 235302 (2008)
- Fig.1 : Electron and hole states in a zincblende GaN/AlN quantum dot. The corresponding energies [eV] are: e0 = 4.4479, e1 = e2 = 4.5761, e3 = 4.6900 for the electrons and h0 = 0.6708, h1 = 0.6641, h2 = 0.6578, h3 = 0.6539 for the hole states.
