In this work, within a fully atomistic framework, we investigate the electronic structure of wurtzite InN quantum dots self-assembled on GaN substrates. The main objectives are two-fold: (1) to explore the origin, nature and the role of crystal atomicity, strain-field, piezoelectric and pyroelectric potentials in determining the energy spectrum and the wavefunctions, and (2) to address the shift in the ground state, the symmetry-lowering and the non-degeneracy in the first excited state, the strong band-mixing in the overall conduction band electronic states, and their size and geometry dependence—a group of inter-related phenomena that has been revealed in recent spectroscopic analyses. We also demonstrate the importance of 3D atomistic material representation, and the need for using realistically-extended substrate and cap layers (multimillion atom modeling) in studying the built-in fields in these reduced-dimensional QDs. Models used in this study are as follow: (1) VFF Keating model for atomistic strain relaxation; (2) 20-band nearest-neighbor sp3d5s* tight-binding model for the calculation of single-particle energy states; and (3) microscopically determined polarization constants in conjunction with an atomistic 3-D Poisson solver for the calculation of piezo- and pyro- electric contributions.
Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2010: Electronics, Devices, Fabrication, MEMS, Fluidics and Computational
Published: June 21, 2010
Pages: 37 - 40
Industry sector: Sensors, MEMS, Electronics