Theoretical study of the electronic structure of self-organized GaN/AIN QDs

摘要

We present the results of a theoretical study of the electronic structure of self-organized GaN/AlN quantum dots (QDs) with a hexagonal truncated pyramid shape. Our analysis takes into account the effects of built-in elastic strain, and of the piezoelectric and spontaneous polarization, and is carried out in the framework of a multi-band koP model. A novel Green function technique which we have developed previously is used to calculate the 3D distribution of the strain and of the built-in electric field in each QD structure. The QD carrier spectra and wavefunctions are calculated using a plane-wave expansion method. We show that due to the strong built-in electric field the electrons are localized near the QD top and the holes are localized in the wetting layer just below the pyramid. These electric fields also provide additional lateral localization of the carriers, so that the effective lateral size off the dot becomes smaller. The energy of the ground state optical transition decreases with increasing dot size, in good quantitative agreement with available experimental data.