TEM investigations on growth interrupted samples for the correlation of the dislocation propagation and growth mode variations in AlGaN deposited on SiN  interlayers

Klein, Oliver; Biskupek, Johannes; Forghani, Kamran; Scholz, F.; Kaiser, Ute

doi:10.1016/j.jcrysgro.2011.03.050

Cited by 30 publications

(27 citation statements)

References 34 publications

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“…The inclination angle was difficult to estimate precisely because of electron penetration and carrier diffusion inside the sample; however, the appearance was similar to the bundled dislocations in AlGaN epitaxial layers grown with lateral coalescence through SiN x nanomasks. 5 Our surface SEM images taken in panchromatic mode also showed dark hillock edges (such as in Fig. 3(b)), indicating the presence of defects at hillock edges.…”

Section: Resultsmentioning

confidence: 51%

“…These results indicate that the mechanism of hillock evolution has at least two origins, namely relaxation of compressive strain in AlGaN epitaxial layers and structural changes induced by Si incorporation (such as an anti-surfactant effect or a nano-mask effect). 4,5 Figures 1(b) and 3(b) show panchromatic CL images of AlGaN epitaxial layers with different relative Al content and with different Si concentration taken at 80 K, respectively. The observation positions were identical to those in the corresponding SEM images.…”

Section: Resultsmentioning

confidence: 99%

“…19 Also, the island boundary regions contained a large number of dislocations. 5,20 In addition, the facet edges in our AlGaN epitaxial layers tend to be Ga-rich regions, and thus a local strain field is introduced at the coalescence boundary. Therefore, it is likely that impurities and/or point defects are concentrated locally and exhibit peculiar properties.…”

Section: Resultsmentioning

confidence: 99%

“…2) at room temperature. It is well known that Si doping into an Al x Ga 1-x N epitaxial layer drastically changes its structural, electrical, and optical properties through phenomena, such as dislocation inclination, 3 nano-mask effect, 4,5 changes in electric conductivity, 6,7 cathodoluminescence (CL) intensity enhancement, 8 introduction of point defects, 9 and changes in optical polarization along with variation in strain state. 10,11 For the fabrication of high-efficiency devices, it is important to investigate in detail the effects of Si doping on AlGaN ternary alloys.…”

Section: Introductionmentioning

confidence: 99%

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Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Kurai¹,

Ushijima²,

Miyake³

et al. 2014

Journal of Applied Physics

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The spatial distribution of luminescence in Si-doped AlGaN epitaxial layers that differ in Al content and Si concentration has been studied by cathodoluminescence (CL) mapping in combination with scanning electron microscopy. The density of surface hillocks increased with decreasing Al content and with increasing Si concentration. The mechanisms giving rise to those hillocks are likely different. The hillocks induced surface roughening, and the compositional fluctuation and local donor-acceptor-pair (DAP) emission at hillock edges in AlGaN epitaxial layers were enhanced irrespective of the origin of the hillocks. The intensity of local DAP emission was related to Si concentration, as well as to hillock density. CL observation revealed that DAP emission areas were present inside the samples and were likely related to dislocations concentrated at hillock edges. Possible candidates for acceptors in the observed DAP emission that are closely related in terms of both Si concentration and hillock edges with large deformations are a V III -Si III complex and Si N , which are unfavorable in ordinary III-nitrides. V C 2014 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 51%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Kurai¹,

Ushijima²,

Miyake³

et al. 2014

Journal of Applied Physics

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“…[14][15][16][17][18][19] As mentioned in Ref. 18, Burgers vector analysis is required to prove this.…”

Section: Introductionmentioning

confidence: 97%

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

et al. 2016

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The behavior of dislocations in a GaN layer grown on a 4-inch Si(111) substrate with an AlGaN/AlN strained layer superlattice using horizontal metal-organic chemical vapor deposition was observed by transmission electron microscopy. Cross-sectional observation indicated that a drastic decrease in the dislocation density occurred in the GaN layer. The reaction of a dislocation (b=1/3[-211-3]) and anothor dislocation (b =1/3[-2113]) to form one dislocation (b =2/3[-2110]) in the GaN layer was clarified by plan-view observation using weak-beam dark-field and large-angle convergent-beam diffraction methods.

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In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN

Forghani

Gharavipour

Klein

et al. 2011

Phys. Status Solidi C

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We report the growth of high crystal quality Al0.3Ga0.7N directly on sapphire substrates with metalorganic vapour phase epitaxy. We studied the improvements in crystal quality by introducing an in‐situ deposited SiNx interlayer. It acts as a nanomask which results in termination of the dislocations near the interface between the nanomask and epilayer. The epilayers with no SiNx interlayer have very low density of screw type dislocations evident from transmission electron microscopy (TEM) investigations confirmed by a very narrow X‐ray diffraction symmetric reflection (60”). This is a result of our oxygen doped AlN nucleation layer used to grow such epilayers. On the other hand, such epilayers have very broad XRD asymmetric reflections (typically a few thousand arcsec) indicating a high density of edge type dislocations. We could decrease the latter which are the main existing dislocations in our AlGaN epilayers. In TEM micrographs, we observed the formation of dislocation “bundles” when introducing SiNx interlayers. This phenomenon promotes the dislocation free areas on the surface of the wafer. We carried out accurate optimizations of the SiNx deposition. Consequently, we could grow high quality Al0.3Ga0.7N epilayers with much narrower XRD asymmetric peaks–782” with total sample thickness of 1.4 µm (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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TEM investigations on growth interrupted samples for the correlation of the dislocation propagation and growth mode variations in AlGaN deposited on SiN interlayers

Cited by 30 publications

References 34 publications

Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN

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TEM investigations on growth interrupted samples for the correlation of the dislocation propagation and growth mode variations in AlGaN deposited on SiN interlayers

Cited by 30 publications

References 34 publications

Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Inhomogeneous distribution of defect-related emission in Si-doped AlGaN epitaxial layers with different Al content and Si concentration

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

In‐situ deposited SiNx nanomask for crystal quality improvement in AlGaN

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In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN