Study on defects and confined energy level of InAs/GaAs quantum dot system

The energy levels of InAs/GaAs quantum dot (QD) system have been studied by performing the electrical measurements such as capacitance-voltage and deep-level transient spectroscopy methods. The InAs QDs were grown at 490-bar C under various InAs thicknesses with self-assembled growth method by molecular beam epitaxy. While any defects did not appear in as-grown GaAs epi-layers, InAs/GaAs QD system grown at low-temperature showed several levels including interface states. After hydrogen plasma treatment to QD system, the activation energy from QD energy states were estimated as 0.41eV in the sample with InAs of 2.5mono-layers (MLs) and 0.38eV in 2.0 MLs InAs sample