Analysis of energy levels of InAs/GaAs self-assembled quantum dots by using C-V and deep level transient spectroscopy

Energy levels of InAs/GaAs self-assembled quantum dot (QD) system were analyzed by capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) methods. The QD signals were partially separated by DLTS measurement with small bias changing. The activation energies of AD signals were varied from 66 meV to 610 meV by changing of 0.6 V applied bias, which energies are related to the confined energy levels of InAs QDs. Then the ground states of InAs QDs were considered to be located 0.61 eV below the conduction band edge of GaAs barrier. In addition, it showed that DLTS signal of QDs are largely affected by their density of energy state. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim