Ballistic electron emission spectroscopy/microscopy of self-assembled InAs quantum dots of different sizes embedded in GaAs∕AlGaAs heterostructure

Self-assembled InAs quantum dots embedded in GaAs∕GaAlAs heterostructure were visualized by ballistic electron emission microscopy. The spectroscopic characteristics on individual quantum dots were examined. Quantum dots had images of elliptical shapes. Their length was from about 10to20nm. Below one-electron p1-like state, one-electron and two-electron ground states and excited two-electron states were observed. The Coulomb interaction and exchange energies between two electrons in quantum dots were determined and compared with the previously published theoretical results.