Authors: H. Choi, Y. Jeong, Y. Park, J. Lee, J-Y Leem and M. Jeon
Affilation: Inje University, Korea
Pages: 44 - 47
Keywords: quantum dot, GaAs, superlattice, MBE
We investigated the effect of AlGaAs/GaAs superlattice barriers on the optical properties of InAs quantum dots (QDs) by using photoluminescence (PL) spectroscopy. The samples used in the present work were grown by molecular beam epitaxy (MBE) on the (100) semi-insulated GaAs substrates. Five different types of sample structures were designed and grown to investigate the effects of AlGaAs/GaAs superlattice barriers. In order to identify the effect superlattice barrier, simple GaAs/InAs QD/GaAs structure was also grown as a reference. The structures are GaAs/InAs/GaAs (S1) ,GaAs/Al0.112Ga0.888As/InAs/Al0.111Ga0.888As/GaAs(S2), GaAs/Al0.285Ga0.715As/InAs/Al0.285Ga0.715As/GaAs (S3), GaAs/Al0.112Ga0.888As/GaAs´10/InAs/GaAs/Al0.112Ga0.888As´10/GaAs (S4) and GaAs/ Al0.285Ga0.715As/GaAs´10/InAs/GaAs/Al0.285Ga0.715As´10/GaAs (S5). The schematic diagram for sample structures is shown in Figure 1 in terms of band gap. The photoluminescence spectra were recorded and analyzed. In case of the sample S2 and S3, the emission peak positions from InAs QDs embedded in thick AlGaAs barrier were blue-shifted from that of reference sample(S1) by the amount of 55 meV and 102 meV, respectively. However, the PL intensity was drastically decreased with large broadening in PL linewidth from 44 meV to 75 and 80 meV for the ground state. On the other hand, in case of InAs QDs inserted in between AlGaAs/GaAs superlattice barriers, the emission peak position was blue-shifted just like the InAs QDs with thick AlGaAs barrier. However, the linewidths and PL intensity were greatly improved. Figure 2 show the PL spectra for samples of five different structures. From these results, the AlGaAs/GaAs superlattice barriers can effectively change the emission peak position of InAs QDs without much sacrifying the optical characteristics of QD structures.