Dependence of quantum dot Auger carrier relaxation on barrier dimensionality: an experimental study
We present picosecond time resolved photoluminescence measurements of GaAs/AlGaAs quantum dot structures—grown by modified droplet epitaxy—where the dimensionality of the barrier states has been varied from 2D to 3D. This is realized by the insertion of a variable thickness quantum well at the quantum dot base. We find a fast carrier relaxation, which is made faster by the increase of the photogenerated carrier injection in all the samples due to Auger-like mechanisms. Hence the dimensionality of the electronic states in the barrier is not relevant in determining the quantum dot capture, in contrast with the conclusions of several models so far presented in the literature. Our findings suggest that the Auger-like processes only involve the zero-dimensional levels of the quantum dots.