Tunneling emission from self-assembled InAs quantum dots probed with capacitance transients

The electron escape from self-assembled InAs quantum dots embedded in GaAs-Schottky diodes is probed with time-resolved capacitance measurements. We present the tunneling-transient spectroscopy technique to derive information on the barrier potential and the quantum dot level structure from the electric-field dependence of the capacitance transients. The data reveal that emission from s- and p-like quantum dot states can clearly be resolved. The barrier potential derived with this method in a simple triangular well model is in good agreement with values derived from measurements of the thermionic emission, if the emission from the s-type dot level is analyzed. The emission from dots occupied with more than one electron is discussed within a simple one-dimensional tunneling model. It reveals that the triangular well model underestimates the well potential by a value close to the Coulomb charging energy.