Effects of matrix layer composition on the structural and optical properties of self-organized InGaN quantum dots

Abstract

Articles you may be interested inInGaN/GaN quantum well structures with greatly enhanced performance on a-plane GaN grown using selforganized nano-masks Appl.Effects of stacking on the structural and optical properties of self-organized GaN/AlN quantum dots Appl. Phys. Lett. 84, 4224 (2004); 10.1063/1.1755840Room-temperature lasing oscillation in an InGaN self-assembled quantum dot laser Self-organized InGaN quantum dots (QDs) with emission wavelength from green to red range have been grown on GaN templated c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD). The effects of matrix layer composition on the structural and optical properties of InGaN QDs have been investigated. A continued growth of QDs is observed during the growth of In 0.1 Ga 0.9 N matrix layer, which results in an increase of the QDs' size. By using In 0.1 Ga 0.9 N matrix layer instead of GaN one, the annealing induced blue-shift in emission energy of the InGaN QDs can be suppressed. After the growth of top GaN cap layer, a larger red-shift caused by the quantum confined Stark effect is observed in the sample with In 0.1 Ga 0.9 N matrix layer. Employing this method, InGaN QD sample emitting at 615 nm with an internal quantum efficiency of 24.3% has been grown. The significance of this method is that it allows a higher growth temperature of InGaN QDs with emission wavelength in the green range to improve the crystalline quality, which is beneficial to enhance the efficiency of green InGaN QD light-emittingdiodes and laser diodes. V C 2013 AIP Publishing LLC. [http://dx.

Strong localization effect and carrier relaxation dynamics in self-assembled InGaN quantum dots emitting in the green

“…The InGaN self-assembled QD sample investigated in this work was epitaxially grown on a (0001)-oriented sapphire by MOCVD system [ 22 ]. A schematic diagram of the QD epitaxial structure is shown in Figure 1 .…”

“…Other detailed growth procedures are available in ref. [ 22 ]. Cross-section Z-contrast scanning transmission electron microscopy (STEM) shows that the diameters of the QDs range from 20 to 60 nm, while the average height of QDs is about 2.5 nm.…”

Broadband full-color monolithic InGaN light-emitting diodes by self-assembled InGaN quantum dots

“…However, the luminescence efficiency of InGaN LEDs drops dramatically at this range, which is well known as “green gap” 11 12 13 . To circumvent this problem inherent in InGaN MQWs, an alternative InGaN quantum dots (QDs) structure as light-emitters has been suggested in the green or even longer spectral ranges 14 15 16 17 18 19 20 21 22 23 . The self-assembled QDs have significantly reduced built-in piezoelectric polarization field, leading to an alleviation of quantum confinement stark effect (QCSE) as compared to the planar QWs 14 15 16 17 18 .…”

Modeling of the Interminiband Absorption Coefficient in InGaN Quantum Dot Superlattices

“…In MQDs' structure in which each nanostructure can be assumed as a single QD (the absence of wavefunction overlap among those of different QDs), the main absorption coefficient component is related to QDs' bound excitons [35,43,47,[49][50][51][52]. Instead, in this paper, our investigation is focused on absorption coefficient components derived by thesuperlattice nature of high density QD heterostructures.…”

“…Finally, the absorption coefficient in thermal equilibrium (see Appendix C) has been calculated by considering the non-parabolicity of minibands, the light polarization influence and the strain dependence, as well asintroducing the absorption coefficient component related to free Another approximation used here is on QDs' geometrical structure. Indeed, actual and most investigated self-assembled QDs' shape is sometimes like a hexagonal pyramid [47,48], a truncated hexagonal pyramid [1,49,50] or a lens [51], but since minibands' properties derive from a very large QD number, in the first approximation, it is possible to assume that QDSL miniband formation and properties are less influenced by the exact QDs shape when compared to their mean sizes and inter-distances. Indeed, our numerical investigations performed in isolated In 0.4 Ga 0.6 N/GaN cuboid QD with sizes 6ˆ6ˆ3 nm 3 reveals that the overlap value of the envelope functions is 0.77, while in [47], for the In 0.4 Ga 0.6 N/GaN QD with a truncated hexagonal pyramid shape, a value of about 0.72 has been obtained.…”