Energy levels of InAs/InP QD system with GaAs and InGaAs insertion layers by C-V and DLTS methods

We have studied the electrical properties of InAs/InP self-assembled quantum dots (SAQDs) with GaAs and InGaAs thin layers by capacitance-voltage and deep level transient spectroscopy measurements. The thermal activation energies for electron emission from InAs/InP SAQDs with 5 mono-layers GaAs and 17 mono-layers InGaAs insertion were obtained 0.60 eV and 0.54 eV, respectively, and that in normal QD sample without insertion layer appeared 0.57 eV. On the other hand, the capture barrier heights of QDs with GaAs and InGaAs inserted samples and without insertion were measured 0.24 eV, 0.08 eV and 0.18 eV, respectively, from GaAs conduction band edge. These results show that the strain in the QDs layer effects to the capture barrier height as well as the quantum confined level.