Discretization of Electronic States in Large InAsP / InP Multilevel Quantum Dots Probed by Scanning Tunneling Spectroscopy

The topography and the electronic structure of $\mathrm{InAsP}/\mathrm{InP}$ quantum dots are probed by cross-sectional scanning tunneling microscopy and spectroscopy. The study of the local density of states in such large quantum dots confirms the discrete nature of the electronic levels whose wave functions are measured by differential conductivity mapping. Because of their large dimensions, the energy separation between the discrete electronic levels is low, allowing for quantization in both the lateral and growth directions as well as the observation of the harmonicity of the dot lateral potential.