Dislocation reduction in GaN crystal by advanced-DEEP

Motoki, Kensaku; Okahisa, Takuji; Hirota, Ryu; Nakahata, Seiji; Uematsu, Koji; Matsumoto, Naoki

doi:10.1016/j.jcrysgro.2007.03.038

Cited by 117 publications

(76 citation statements)

References 18 publications

(23 reference statements)

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“…As suggested by Weyher et al 17 the growth in well-defined crystallographic direction, e.g. in [10][11] direction with the (10-12) interface, is replaced by the growth in variable direction with clear growth striations. Surprisingly, our results have revealed spatial modulation of the electrical conductivity also in the regions 3(3 ), i.e.…”

Section: Ecs Journal Of Solid State Science and Technology 5 (5) P21mentioning

confidence: 98%

Self-Organized Three-Dimensional Nanostructured Architectures in Bulk GaN Generated by Spatial Modulation of Doping

Tiginyanu

Stevens‐Kalceff

Sarua

et al. 2016

ECS J. Solid State Sci. Technol.

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Self-organized 3D nanostructured architectures including quasi-ordered concentric hexagonal structures generated during the growth of single crystalline n-GaN substrates by hydride vapor phase epitaxy (HVPE) are reported. The study of as-grown samples by using Kelvin Probe Force Microscopy shows that the formation of self-organized architectures can be attributed to fine modulation of doping related to the spatial distribution of impurities. The specific features of nanostructured architectures involved have been brought to light by using electrochemical and photoelectrochemical etching techniques which are highly sensitive to local doping. The analysis of the results shows that the formation of self-organized spatial architectures in the process of HVPE is caused by the generation of V-pits and their subsequent overgrowth accompanied by the growth in variable direction. It is demonstrated for the first time that the electrical and luminescence properties of HVPE-grown GaN are spatially modulated throughout, including islands between overgrown V-pit regions. The dependence of doping upon growth direction is confirmed by the micro-cathodoluminescence characterization of HVPE-grown pencil-like microcrystals exposing various crystallographic planes along the tip. These results are indicative of new possibilities for defect engineering in gallium nitride and for three-dimensional spatial nanostructuring of this important electronic material by controlling the growth direction. Gallium Nitride (GaN), a wide-bandgap semiconductor compound (E g = 3.4 eV at 300 K), is considered nowadays the second most important semiconductor material after Si. Over the past decades it has played a major role in the development of modern solid-state lighting industry.1-3 An intensive investigation of this compound started in 1970's, but with minimal success in the development of real applications. In the absence of native bulk material, GaN epilayers were grown on foreign substrates and, as a result of the large lattice mismatch and difference in thermal expansion coefficients, the overgrown films contained a high concentration of threading dislocations. The fascinating point, however, is that even in the presence of very high concentrations of dislocations, sometimes exceeding 10 10 cm −2 , gallium nitride exhibits intense luminescence, a property that makes the compound unique in comparison with other III-V materials, such as GaAs, GaP and InP. This particular feature along with other material characteristics were of paramount importance for the development and subsequent commercialization of GaN-based blue light emitting diodes by the mid-1990s. 4 This significant optoelectronic success resulted in the Nobel Prize for Physics being awarded to Shuji Nakamura, Isamu Akasaki and Hiroshi Amano, in 2014. There is no doubt that lighting technologies based on GaN and related nitrides will continue their impactful evolution, particularly in view of the recent demonstration of electrically pumped inversionless polariton lasing at room temper...

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Section: Ecs Journal Of Solid State Science and Technology 5 (5) P21mentioning

confidence: 98%

Self-Organized Three-Dimensional Nanostructured Architectures in Bulk GaN Generated by Spatial Modulation of Doping

Tiginyanu

Stevens‐Kalceff

Sarua

et al. 2016

ECS J. Solid State Sci. Technol.

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“…24,25 Several groups have artificially fabricated dot-patterns and grown seed layers by the HVPE method to improve crystallinity. [26][27][28] GaN substrates grown by HVPE methods have high crystalline quality; however, freestanding GaN substrates feature lattice curvature owing to internal stresses, such as compressive and tensile stress. The lattice curvature and dislocation degrades the device performance.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of lattice curvature and crystalline homogeneity for 2-inch GaN homo-epitaxial layer

et al. 2018

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We evaluated the lattice curvature, crystallinity, and crystalline homogeneity of a GaN layer on a free standing GaN substrate using lattice orientation measurements, θ rocking curves, and reciprocal space mapping from synchrotron X-ray diffraction topography, and X-ray diffraction. The lattice curvature of the 2-inch GaN homo-epitaxial layer was a concave bend, which had a curvature radius of approximately 20.7 m. The GaN layer was epitaxially grown on the GaN substrate and had good crystallinity with a high homogeneity.

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“…Currently, hydride vapor phase epitaxy (HVPE) provides the most practical solution to free-standing GaN wafers with the so-called "quasi-bulk" approach, i.e., the growth of a very thick film of GaN on a heteroepitaxial substrate by HVPE followed by the removal of the substrate. (1) In addition, people have attempted to grow bulk GaN crystals on quasi-bulk GaN wafers by HVPE. (2,3) Nevertheless, the reduction in dislocation density in GaN crystals grown on quasi-bulk GaN wafers by HVPE seems to have its limitation; current HVPE-grown GaN substrates have a dislocation density on the order of high 10 5 to low 10 6 cm −2 .…”

Section: Introductionmentioning

confidence: 99%

Ammonothermal Bulk GaN Growth and Its Processing

2014

Sensors and Materials

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In this paper, we overview the current progress of ammonothermal GaN growth at SixPoint Materials, Inc. and discuss issues in wafer processing. Bulk GaN crystals grown in small prototype reactors present a high-quality microstructure as well as an improved transparency. The dislocation density of the crystal is on the order of 4.0 × 10 4 cm −2 . The optical absorption coefficient as low as 4 cm −1 at 450 nm is obtained. Wafer processing techniques, such as wire sawing and chemical mechanical polishing, are one of the challenges in realizing GaN wafers. Crystal cracks are the major and fundamental obstacle in achieving a high-quality surface during wire sawing. The surface quality after chemical mechanical polishing (CMP) is successfully evaluated using X-ray diffraction.

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Dislocation reduction in GaN crystal by advanced-DEEP

Cited by 117 publications

References 18 publications

Self-Organized Three-Dimensional Nanostructured Architectures in Bulk GaN Generated by Spatial Modulation of Doping

Self-Organized Three-Dimensional Nanostructured Architectures in Bulk GaN Generated by Spatial Modulation of Doping

Evaluation of lattice curvature and crystalline homogeneity for 2-inch GaN homo-epitaxial layer

Ammonothermal Bulk GaN Growth and Its Processing

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