Properties of Free-Standing GaN Bulk Crystals Grown by HVPE

1997 ◽  
Vol 482 ◽  
Author(s):  
YU. Melnik ◽  
A. Nikolaev ◽  
I. Nikitina ◽  
K. Vassilevski ◽  
V. Dmitriev
Keyword(s):  
Hydride Vapor Phase Epitaxy ◽  
Bulk Crystals ◽  
Free Standing ◽  
Yellow Band ◽  
Rocking Curve ◽  
X Ray ◽  
Lattice Constants ◽  
Interface Surface ◽  
Peak Intensity ◽  
Residual Strains

AbstractGaN wafers 200 μm thick and 30 mm diameter were fabricated. GaN was grown by hydride vapor phase epitaxy on SiC substrates and removed from the substrate by reactive ion etching. Lateral size of the GaN wafers was equal to the size of the initial SiC substrates. GaN wafers were cleaved in pieces and these pieces were characterised. It was found that after the fabrication, GaN crystals were slightly deformed and strained. An anneal at 830°C in nitrogen ambient eliminated the residual strains. The FWHM of ω-scan (0002) x-ray rocking curve for annealed crystals was less than 140 arcsec for both sides of the best GaN crystals. The lattice constants measured from both sides of the crystals were c =5.1853±0.0003 Å and a = 3.1889±0.0001 Å. The Nd – Na concentration determined by a mercury probe was about 2×1017cm−3 for as-grown GaN surface and about 2×1019cm−3 for former interface surface. Photoluminescence spectrum taken at 17 K revealed an edge peak at 3.472 eV with the FWHM value of 2.3 meV. A ratio of the edge peak intensity to the intensity of yellow band was higher than 1000. Initial TEM experiments were performed.

A high-energy triple-axis X-ray diffractometer for the study of the structure of bulk crystals

2004 ◽  
Vol 37 (6) ◽  
pp. 901-910 ◽  
Author(s):  
C. Seitz ◽  
M. Weisser ◽  
M. Gomm ◽  
R. Hock ◽  
A. Magerl
Keyword(s):  
High Energy ◽  
X Rays ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
High Penetration ◽  
Massive Sample ◽  
Laue Geometry ◽  
The Ideal

A triple-axis diffractometer for high-energy X-ray diffraction is described. A 450 kV/4.5 kW stationary tungsten X-ray tube serves as the X-ray source. Normally, 220 reflections of thermally annealed Czochralski Si are employed for the monochromator and analyser. Their integrated reflectivity is about ten times higher than the ideal crystal value. With the same material as the sample, and working with the WKα line at 60 keV in symmetric Laue geometry for all axes, the full width at half-maximum (FWHM) values for the longitudinal and transversal resolution are 2.5 × 10−3and 1.1 × 10−4for ΔQ/Q, respectively, and the peak intensity for a non-dispersive setting is 3000 counts s−1. In particular, for a double-axis mode, an energy well above 100 keV from theBremsstrahlungspectrum can be used readily. High-energy X-rays are distinguished by a high penetration power and materials of several centimetre thickness can be analysed. The feasibility of performing experiments with massive sample environments is demonstrated.

Photoluminescence Study of Plastically Deformed GaN

2004 ◽  
Vol 831 ◽  
Author(s):  
I. Yonenaga ◽  
H. Makino ◽  
S. Itoh ◽  
T. Goto ◽  
T. Yao
Keyword(s):  
Plastic Deformation ◽  
Near Band Edge ◽  
Threading Dislocations ◽  
Yellow Luminescence ◽  
Bulk Crystals ◽  
Prismatic Plane ◽  
Free Standing ◽  
Yellow Band ◽  
Band Edge Luminescence ◽  
Red Luminescence

ABSTRACTWe report the photoluminescence characteristics of fresh dislocations introduced by the plastic deformation in GaN bulk crystals. GaN crystals prepared from free standing wafers grown by the HVPE technique were compressed plastically at 900 to 1000°C. In the deformed crystals (a/3) (1120) dislocations on the (1110) prismatic plane, corresponding to the so-called threading dislocations, were observed in TEM. In the PL studies at 11K the intensity of the near band-edge luminescence decreased drastically in the deformed GaN by about 1/12 than that of the as-grown GaN, which seems to imply the introduction of a high density of non-radiative reco!m bination centers into GaN! during the plastic deformation. By the plastic deformation the yellow band luminescence decreased remarkably meanwhile the red band and other new luminescence developed relatively. It is found that dislocations do not originate to the yellow luminescence but the red luminescence.

Half‐width and peak‐intensity measurement of a rocking curve obtained from silicon on sapphire using soft x‐ray beams

1977 ◽  
Vol 48 (7) ◽  
pp. 3138-3140 ◽  
Author(s):  
Seigô Kishino ◽  
Shinya Iida ◽  
Shigeru Aoki ◽  
Tatsumi Mizutani ◽  
Tetsuo Watanabe
Keyword(s):  
Half Width ◽  
Intensity Measurement ◽  
Rocking Curve ◽  
X Ray ◽  
Peak Intensity

AlN Wafers Fabricated by Hydride Vapor Phase Epitaxy

1999 ◽  
Vol 595 ◽  
Author(s):  
Andrey Nikolaev ◽  
Irina Nikitina ◽  
Andrey Zubrilov ◽  
Marina Mynbaeva ◽  
Yuriy Melnik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Vapor Phase ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron ◽  
Thick Layers

AbstractWe report on AlN wafers fabricated by hydride vapor phase epitaxy (HVPE). AlN thick layers were grown on Si substrates by HVPE. Growth rate was up to 60 microns per hour. After the growth of AlN layers, initial substrates were removed resulting in free-standing AlN wafers. The maximum thickness of AlN layer was about 1 mm. AlN free-standing single crystal wafers with a thickness ranging from 0.05 to 0.8 mm were studied by x-ray diffraction, transmission electron microscopy, optical absorption, and cathodoluminescence.

Preparation of 30×30 mm2 Free-Standing GaN Wafer by Mechanical Liftoff and Optical Properties in The Backside of The Free GaN by Cathodoluminescence

2000 ◽  
Vol 639 ◽  
Author(s):  
Hwa-Mok Kim ◽  
Jae-Eung Oh ◽  
Tae-Won Kang
Keyword(s):  
Optical Properties ◽  
Beam Energy ◽  
Film Growth ◽  
Hydride Vapor Phase Epitaxy ◽  
Threading Dislocations ◽  
Electron Beam Energy ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Double Crystal ◽  
X Ray

ABSTRACTIn this study, free-standing GaN was produced from 350- to 400-μm-thick GaN films grown on sapphire by using hydride vapor phase epitaxy. The thick films were separated from the substrate by using the mechanical polishing method with a diamond slurry. After liftoff, the bow is slight or absent in the resulting free-standing GaN. Double-crystal X-ray diffraction, hall measurements, and cathodoluminescence were used for characterizing the free-standing GaN wafer. To investigate spatially the backside of the free-standing GaN substrate, we controlled the electron beam energy from 5 keV to 30 keV. As the beam energy increased, dark regions, i.e., nonradiative regions, become smaller than bright regions. We think this means that nonradiative centers, i.e., threading dislocations, merge during film growth.

Growth and Fabrication of 2 inch Free-standing GaN Substrates via the Boule Growth Method

2003 ◽  
Vol 798 ◽  
Author(s):  
Drew Hanser ◽  
Lianghong Liu ◽  
Edward A. Preble ◽  
Darin Thomas ◽  
Mark Williams
Keyword(s):  
Growth Process ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Free Standing ◽  
High Quality ◽  
Rocking Curve ◽  
Atomic Force ◽  
Transmission Electron ◽  
Growth Method ◽  
Quality Material

ABSTRACTHigh quality, single crystal GaN substrates have been demonstrated using a boule growth process. Here we report on the crystalline boules that were formed during the growth process and their material characterization. Using hydride vapor phase epitaxy process, GaN crystals were grown at growth rates greater than 200 μm/hr. Boules greater than 3 mm thick were grown and processed into free-standing substrates. Rocking curve measurements using high-resolution X-ray diffraction were performed on the substrates with FWHM values of 92 and 146 arcsec for the (002) and (102) reflections, respectively. Atomic force microscope images, etch pit studies, and transmission electron micrographs of the GaN material show high quality material quality with a dislocation density in the range of 5×106 to 1×107 cm-2.

Growth, crystalline quality and transition variation of ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ferroelectric crystals

2013 ◽  
Vol 03 (01) ◽  
pp. 1350003
Author(s):  
Linghang Wang ◽  
Zhuo Xu ◽  
Zhenrong Li ◽  
Yuhui Wan ◽  
Junjie Gao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Defect Density ◽  
Growth Direction ◽  
Middle Part ◽  
Rhombohedral Structure ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray

Bulk crystals of high Curie temperature (TC)24 Pb ( In 1/2 Nb 1/2) O 3–43 Pb ( Mg 1/3 Nb 2/3) O 3–33 PbTiO 3 (24PIN–43PMN–33PT) with 55 mm in diameter and 130 mm in length were reproducibly grown by the bottom-seeded Bridgman method. The X-ray diffraction (XRD) spectrum indicated that the as-grown crystal was a single phase with rhombohedral structure at room temperature, the domain morphology and the phase transition sequence of R → T →C were observed, the full width at half maximum (FWHM) of X-ray rocking curve of (002) face was about 0.77°, and the defect density was inferred to 2.56 × 1010cm-2. The measured density of the as-grown crystals was very close to the theoretical one. Variation of the transition temperature of the as-grown crystals along the growth direction revealed that T C increased linearly along the growth direction and rhombohedral to tetrahedral phase transition temperature (T RT ) gradually decreased in the middle part of the ingot.

scholarly journals Хлорид-гидридная газофазная эпитаксия полуполярного слоя AlN(1012) на наноструктурированной подложке Si(100)

2020 ◽  
Vol 46 (2) ◽  
pp. 12
Author(s):  
В.Н. Бессолов ◽  
М.Е. Компан ◽  
Е.В. Коненкова ◽  
В.Н. Пантелеев
Keyword(s):  
Hydride Vapor Phase Epitaxy ◽  
Full Width ◽  
Half Maximum ◽  
X Ray Diffraction ◽  
Inclined Plane ◽  
New Approach ◽  
Rocking Curve ◽  
X Ray ◽  
Patterned Substrate ◽  
Maximum Value

A new approach is proposed to the synthesis of a semipolar AlN on a Si(100) substrate at the surface for which the angle between the inclined plane of the nanogrooves and Si(100) is 47°. It is shown that the hydride vapor-phase epitaxy on a such nano-patterned substrate enables formation of a semipolar layer AlN (1012) characterized by the full width at half maximum value as low as ωθ ~60 arcmin for the x-ray diffraction rocking curve. It is found that the Raman spectra of the semipolar AlN(10-12) layer contain additional peaks on the Raman curves associated with phonons A1(TO) and E1(TO), in contrast to the polar AlN(0001) layer, where the peak A1(LO) is additionally manifested.

A 4 Crystal Monochromator for High Resolution Rocking Curves

1987 ◽  
Vol 31 ◽  
pp. 403-408
Author(s):  
Robert W. Green
Keyword(s):  
Bragg Reflection ◽  
Thin Layers ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Lattice Constants ◽  
Monochromator Crystal ◽  
Parallel Configuration ◽  
Double Crystal Diffractometer

X-ray characterization of single crystal materials in the form of thin layers can be accomplished with the use of a double crystal diffractometer. The resultant rocking curve is a convolution of the Bragg reflection from both the first and second crystals. The width of the rocking curve at half-height is a measure of the crystal perfection of a materiel. Since the FWHM for the material being analyzed cannot be less than that of the first crystal (Monochromator), the first crystal should be of very good crystal quality. The problem that arises with the two crystal parallel configuration (Fig. 1) is that the monochromator crystal must be changed each time a material of different orientation or stoichiometry with different resultant lattice constants is analyzed. This requires changing the monochromator and re-aligning the double crystal diffractometer.

scholarly journals AlN Wafers Fabricated by Hydride Vapor Phase Epitaxy

2000 ◽  
Vol 5 (S1) ◽  
pp. 432-437 ◽  
Author(s):  
Andrey Nikolaev ◽  
Irina Nikitina ◽  
Andrey Zubrilov ◽  
Marina Mynbaeva ◽  
Yuriy Melnik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Vapor Phase ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron ◽  
Thick Layers

We report on AlN wafers fabricated by hydride vapor phase epitaxy (HVPE). AlN thick layers were grown on Si substrates by HVPE. Growth rate was up to 60 microns per hour. After the growth of AlN layers, initial substrates were removed resulting in free-standing AlN wafers. The maximum thickness of AlN layer was about 1 mm. AlN free-standing single crystal wafers with a thickness ranging from 0.05 to 0.8 mm were studied by x-ray diffraction, transmission electron microscopy, optical absorption, and cathodoluminescence.

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