Investigation of strain in self-assembled multilayer InAs/GaAs quantum dot heterostructures

A detailed study of defect formation, as a result of large dots synthesis, in stacked InAs/GaAs quantum dots (QDs) was performed using double crystal x-ray diffraction, transmission electron microscopy, atomic force microscopy and photoluminescence. Three stacked samples with varying InAs nominal thicknesses but fixed GaAs 'spacer' of 25 nm were grown by molecular beam epitaxy (MBE). For these large dots emitting near 1.3 ?m, the formation of coherent QDs was accompanied by 'volcano-like' defects and extended defects such as threading dislocations. Power dependence photoluminescence revealed a bimodal distribution of small dots coexisting with the large dots. Surface depressions due to lattice bending within the sample were also observed. The 'volcano-like' defects which extended all the way to the surface had a surface density of the order of 109 cm?2. Remarkably, significant improvements in photoluminescence intensity were observed when the material was etched to selectively remove the topmost stacks thus demonstrating that the 'volcano-like' defects were responsible for the severely suppressed photoluminescence efficiencies. For nominal InAs thickness of 2.73 monolayers, an optimal stack of three periods yielded the highest photoluminescence intensity before the onset of defects.

https://iopscience.iop.org/article/10.1088/0268-1242/22/2/014/pdf

Formation and role of defects in stacked large binary InAs/GaAs quantum dot structures

Improvements of stacked self-assembled InAs/GaAs quantum dot structures for 1.3µm applications

AlGaInAs capping layer impact on emission and structure of AlGaAs/GaAs quantum wells with InAs quantum dots

Molecular Beam Epitaxy growth and characterization of silicon – Doped InAs dot in a well quantum dot infrared photo detector (DWELL-QDIP)

Structural and photoluminescence characteristics of molecular beam epitaxy-grown vertically aligned In0.33Ga0.67As/GaAs quantum dots

Horizontal casting for the growth of Hg1-xCdxTe by solid state recrystallization

The lattice deformation caused by 100 MeV Ti7+ ion irradiation in Si (100) has been studied using X-ray topographic techniques. An important finding is the appearance of a strain field perpendicular to the ion beam direction in the irradiated region well separated from the projected range of implanted ions. This in-plane strain extends in the bulk of the sample and is not merely confined to the surface. The implanted region has been found to experience an out of plane strain which is expected to be tensile in nature.

R.K. Sharma

Papers

Structural and photoluminescence characteristics of molecular beam epitaxy-grown vertically aligned In0.33Ga0.67As/GaAs quantum dots

Horizontal casting for the growth of Hg1-xCdxTe by solid state recrystallization

X-ray Topography of Strain Fields Induced by 100 MeV Ti7+ Ion Irradiated Si(100)