Energy level control for self-assembled InAs quantum dots utilizing a thin AlAs layer

Abstract

Ground-state energy of InAs quantum dots (QDs) in the GaAs matrix can be changed significantly by introducing a thin AlAs layer (1 nm). The photoluminescence (PL) peak position of the QDs grown directly on the thin AlAs layer is blueshifted by 171 meV from that of the QDs grown without the AlAs layer. QDs grown on an additional GaAs thin layer on top of the AlAs layer have PL peaks systematically redshifted to lower energy as the GaAs layer becomes thicker. Time-resolved PL shows that the QDs have similar lifetimes, attesting to the fact that all the QDs grown in this way are of high quality, although the energy level change is large and a thin AlAs layer is introduced.

Formation of self-assembled InAs quantum dots on InAl(Ga)As/InP and effects of a thin GaAs layer

“…With an increase in the GaAs thickness, the emission peak position is blue-shifted and the PL intensity is decreased. The blue-shift and a decrease in PL intensity can be explained by high-potential barrier of a thin GaAs layer and reduction in the QD size [11,12], and a decrease in QD density, respectively, which were confirmed by AFM images as shown in Fig. 5.…”

“…This change in surface reconstruction may result in the modification of the InAs QD nucleation. The change in the interdiffusion behavior of group III elements between the QD layer and the barrier material was partially responsible for the modification in size and shape of a QD [11,12]. Fig.…”

Evolution of bimodal size-distribution on InAs coverage variation in as-grown InAs/GaAs quantum-dot heterostructures

“…Excitation-power-and temperature-dependent PL spectra were taken in the ranges of nominal output power of 1-110 mW and temperature of 15-250 K, respectively, and the luminescence signal was detected and recovered by a liquid-nitrogen-cooled Ge detector and a lock-in amplifier. The details of the epitaxial growth and the basic properties have been reported elsewhere [3][4][5].…”

“…By virtue of unique zerodimensional features and strong confinement of the carrier wave functions in QDs, the structures have emerged as scientifically important systems not only in device applications but also in fundamental studies. Although a number of efforts have been made on (InGa)As-based QDs in order to clarify the formation mechanism and the related characteristics by using a variety of theoretical and experimental approaches so far [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], unusual behaviors associated with the QD size-distribution are still rather ambiguous and unsettled. Previously, a number of research groups have presented some discussions on distinctive behaviors that appeared in photoluminescence (PL) spectra of QD ensembles with bimodal or multimodal size-distribution.…”

Structural and optical properties of GaAs/AlGaAs superlattice layer on InAs quantum dots

“…However, precise modulation is required when long wavelengths are used, and few studies have considered short-wavelength modulation [10][11][12][13][14][15]. Short wavelengths have been investigated using InAs QDs embedded in an Al(Ga)As high potential barrier [16,17], but despite effective wavelength modulation, structural defects associated with the aluminum still restricted possible applications. Hence, there is an urgent need for a study of the optical characteristics of the wetting layer and of the AlGaAs layer that is inserted to reduce the influence of defects and of the correlation between them.…”