Study on the Energy level Properties of InGaAs/InGaAsP Self-Assembled Quantum Dots with Two Different Sizes

Abstract

We studied and characterized the energy levels of the InGaAs/InGaAsP quantum dot (QD) system with two differently sized layers by performing capacitance-voltage and deep-level transient spectroscopy (DLTS) measurement. The sample has two QD layers stacked with different sizes and a spacer layer of 100-nm in thickness. In the DLTS measurement for the QD sample with a 100 nm spacer, several signals were observed. The origins of two signals among them were estimated to be a ground state and a high order confined energy level in this QD system with two kinds of QDs. The highest activation energy from small QDs was about 0.29 eV and this value represented the location of the ground state energy level. A band diagram of the double quantum dot system was suggested based on the DLTS measurements for various filling pulses and bias voltages.