We investigate energy level quantization in self-assembled InGaAs quantum dots that are embedded In a GaAs matrix. We use capacitance and photoluminescence spectroscopy to analyze the evolution of the energy levels with varying amounts of deposited InGaAs. These techniques suggest that the size distribution of the quantum dots contains two well-separated peaks. Transmission electron microscopy confirms a bimodal size distribution and further shows that the big and the small quantum dots have different shapes. In addition, we use an effective-mass based method to calculate the lower energy states of quantum dots with the physical dimensions obtained by transmission electron and atomic force microscopies. our results allow us to construct the energy level diagrams of the two kinds of quantum dots.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Pub Type: Journals
atomic force microscopy, capacitance spectroscopy, energy levels, photoluminescence, quantum dots, transmission electron microscopy