Thesis presented March 15, 2007

Abstract:
We studied by optical spectroscopy the electronic properties of GaN/AlN quantum dots (QDs) grown by molecular beam epitaxy along the non-polar direction [11-20] (a axis). In this orientation a strong reduction of the internal electric field effects present in the [0001] axis (c axis) heterostructures is expected. This could be experimentally verified through time resolved and time integrated photoluminescence (PL) experiments performed on ensembles of dots.
By making a UV dedicated microPL setup we could isolate the first a-plane GaN single QDs spectra. Local charge effects responsible for PL line broadening (spectral diffusion) could be displayed and partly controlled by a vertically applied electric field.
The temperature dependence of the single quantum dot lines allowed us to study the coupling between the confined exciton and the acoustic phonons. The modeling of this mechanism so as the decay time values indicate that the lateral localization of the exciton is stronger than that imposed by the dot.

Keywords:
Single quantum dots, a-plane nitride semiconductors, quantum confined Stark effect, microspectroscopy, oscillator strength, exciton-phonons coupling, electric field, localization

On-line thesis.