TEM analyses of wurtzite InGaN islands grown by MOVPE and MBE

Pretorius, A.; Yamaguchi, Tomohiro; Kübel, Christian; Kröger, Roland; Hommel, D.; Rosenauer, A.

doi:10.1002/pssc.200565333

Cited by 16 publications

(21 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The aspect ratio of ~2.1 (diameter/height) is the lowest in the InGaN/GaN material system, to the best of our knowledge. The InGaN dots themselves were found to be without misfit dislocations and with pronounced facets from the results of TEM observations [8]. From these results, it was confirmed that dots could be formed in the S-K growth mode, where the formation of a strained 2D wetting layer is followed by relaxation through the formation of 3D islands, during MOVPE growth as well as MBE growth.…”

Section: Uncapped Layersupporting

confidence: 69%

See 1 more Smart Citation

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

Yamaguchi

Einfeldt

Gangopadhyay

et al. 2006

Phys. Status Solidi (c)

Self Cite

View full text Add to dashboard Cite

The heteroepitaxial growth of InGaN on GaN was studied by in-situ reflection high-energy electron diffraction, atomic force microscopy, scanning tunneling microscopy and transmission electron microscopy. The misfit strain between InGaN and GaN was relaxed by the deposition of a few-nm-thick wetting layer and the subsequent formation of nano-islands without misfit dislocations, which is the so-called StranskiKrastanov growth mode. Thus, InGaN nano-islands with a very high density of around 10 12 cm -2 and a very small aspect ratio of ~2.1 (diameter/height) were achieved. In this paper, we also discuss the problems regarding GaN overgrowth of an InGaN nano-island layer.

show abstract

Section: Uncapped Layersupporting

confidence: 69%

“…2a. The layer thickness of 1.9-2.7 nm and the In concentration of 0.22±0.03 were derived from the results of TEM observations [8]. When the layer was grown for 35 s, the nano-islands were observed, as shown in Fig.…”

Section: Uncapped Layermentioning

confidence: 99%

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

Yamaguchi

Einfeldt

Gangopadhyay

et al. 2006

Phys. Status Solidi (c)

Self Cite

View full text Add to dashboard Cite

show abstract

“…To achieve the intended indium concentration x of 0.2, the growth temperature of the InGaN was 600 8C and the In/group III flux ratio was 0.58. By variation of the duration of InGaN deposition from T g ¼ 17 to 35 and 52 s, three samples were obtained, which differ only in the nominal thickness of the InGaN layer [25]. Representative HRTEM images of the samples are displayed in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Analyses of HRTEM images exhibited that all islands are pure wurtzite. Again, the islands are relaxed by equidistant misfit dislocations [25]. We did not find misfit dislocations or stacking faults in the wetting layer in between the islands.…”

Section: à2mentioning

confidence: 92%

Microstructural and compositional analyses of GaN‐based nanostructures

Pretorius

Schmidt

Aschenbrenner

et al. 2011

Physica Status Solidi (b)

View full text Add to dashboard Cite

Composition and microstructure of GaN-based island structures and distributed Bragg reflectors (DBRs) were investigated with transmission electron microscopy (TEM). We analysed free-standing InGaN islands and islands capped with GaN. Growth of the islands performed by molecular beam epitaxy (MBE) and metal organic vapour phase epitaxy (MOVPE) resulted in different microstructures. The islands grown by MBE were plastically relaxed. Cap layer deposition resulted in a rapid dissolution of the islands already at early stages of cap layer growth. These findings are confirmed by grazingincidence X-ray diffraction (GIXRD). In contrast, the islands grown by MOVPE relax only elastically.Strain state analysis (SSA) revealed that the indium concentration increases towards the tips of the islands. For an application as quantum dots, the islands must be embedded into DBRs. Structure and composition of Al y Ga 1-y N/GaN Bragg reflectors on top of an AlGaN buffer layer and In x Al 1-x N/ GaN Bragg reflectors on top of a GaN buffer layer were investigated. Specifically, structural defects such as threading dislocations (TDs) and inversion domains (IDs) were studied, and we investigated thicknesses, interfaces and interface roughnesses of the layers. As the peak reflectivities of the investigated DBRs do not reach the theoretical predictions, possible reasons are discussed.

show abstract

“…The challenge is the capping process with (Al)GaN. Transmission electron microscopy analysis shows already a dissolution of the QDs when covered by a 10 nm thick GaN capping layer [3].…”

mentioning

confidence: 99%

Improved capping layer growth towards increased stability of InGaN quantum dots

Tessarek

Yamaguchi

Figge

et al. 2009

Phys. Status Solidi (c)

View full text Add to dashboard Cite

Improvements in GaN capping layer growth towards increased stability of InGaN quantum dots (QDs) will be presented. Surface quality is enhanced with changing the carrier gas during GaN capping layer growth from nitrogen to hydrogen. Without a dissolution of QDs it is possible to increase the temperature to 1050 °C applying a temperature ramp during growth of GaN. Dot stacks with an uniform and up to room temperature bright photoluminescence emission spectra is reported qualifying the structure to be incorporated into LED and laser structures. Finally, the evolution of the nucleation layer into flat and broad island‐like structures will be explained by the spinodal decomposition model (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

TEM analyses of wurtzite InGaN islands grown by MOVPE and MBE

Cited by 16 publications

References 13 publications

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

Microstructural and compositional analyses of GaN‐based nanostructures

Improved capping layer growth towards increased stability of InGaN quantum dots

Contact Info

Product

Resources

About