Characterization of self-assembled InAs quantum dots with InAlAs∕InGaAs strain-reduced layers by photoluminescence spectroscopy

Abstract

The optoelectronic characteristics of self-assembled InAs quantum dots ͑QDs͒ with strain-reduced layers ͑SRLs͒ were investigated using photoluminescence ͑PL͒ spectroscopy. Various SRLs that combine In 0.14 Al 0.86 As and In 0.14 Ga 0.86 As with the same total thickness were examined to ascertain their confining effect on carriers in InAs QDs. The emission wavelength is blueshifted as the thickness of InAlAs is increased. The energy separation between the ground state and the first excited state of QDs with InAlAs SRLs greatly exceeds that of QDs with InGaAs SRLs. Atomic force microscopic images and PL spectra of the QD samples demonstrated that high-quality InAs QDs with long emission wavelengths and a large energy separation can be generated by growing a low-temperature, thin InAlAs SRL onto self-assembled QDs.

Altering the Optical Properties of GaAsSb-Capped InAs Quantum Dots by Means of InAlAs Interlayers

“…Inserting 20 Å of In 0.15 Al 0.85 As (sample B) induces a blueshift of the ground state transition by 52 meV. The blueshift is consistent with what have been observed when a composite InAlAs/InGaAs was used for QDs grown at nearly the same growth temperature [27]. The ground state transition energy blueshift of the InAs QDs in sample B results from the increased confinement potential [15].…”

The role of wetting layer states on the emission efficiency of InAs/InGaAs metamorphic quantum dot nanostructures

“…However, when QDs are embedded in nm-thick InAlAs layers with an energy gap larger than that of InGaAs CLs, such additional barriers are effective in enhancing carrier confinement and, then, η [4,13]. Also in simpler structures InAlAs barriers have been shown to increase the emission efficiency [14][15][16]. The emission blueshift related to the enhancement of barriers can be compensated for by a larger strain relaxation of QDs that can be obtained by slightly larger LCL thicknesses [4,13].…”

Self-assembled InAs quantum dot formation on GaAs ring-like nanostructure templates

“…For example, in one method of self-assembly based on the Stranski-Krastanov (SK) growth mode [14,15], lattice strain drives deposited films into three-dimensional structures. That is, in this SK-based growth mode, one material is deposited on a different material surface so that a lattice-mismatch between the two materials creates strain and drives the growth of a nanostructure.…”

“…Because of the need to control the size, shape, and distribution of these zero-dimensional structures, much effort has been put forth to fabricate QDs with uniformity and precision. Different methods have attempted to fulfill this task, including chemical synthesis [8], lithography [9][10][11], STM and AFM tip-assisted deposition [12,13], and self-assembly [14][15][16][17][18]. The growth of unique complex structures such as rings, ensembles of dots, and molecules have been successfully demonstrated [16,19,20].…”