scholarly journals A Comparative Study of Dislocations in HVPE GaN Layers by High-Resolution X-Ray Diffraction and Selective Wet Etching

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Vladimir Ivantsov ◽  
Anna Volkova
Keyword(s):  
Elevated Temperature ◽  
High Resolution ◽  
Dislocation Density ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Wet Etching ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dislocation Etching

It has been shown during the present study that the E-etching at elevated temperatures can be adopted for the dislocation etching in hydride vapor-phase epitaxy (HVPE) GaN layers. It has been found that the X-ray diffraction (XRD) evaluation of the dislocation density in the thicker than 6 μm epilayers using conventional Williamson-Hall plots and Dunn-Koch equation is in an excellent agreement with the results of the elevated-temperature E-etching. The dislocation distribution measured for 2-inch GaN-on-sapphire substrate suggests strongly the influence of the inelastic thermal stresses on the formation of the final dislocation pattern in the epilayer.

Evaluation of threading dislocation density of strained Ge epitaxial layer by high resolution x-ray diffraction

2017 ◽  
Vol 26 (12) ◽  
pp. 127309 ◽  
Author(s):  
Yuan-Hao Miao ◽  
Hui-Yong Hu ◽  
Xin Li ◽  
Jian-Jun Song ◽  
Rong-Xi Xuan ◽  
...  
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Epitaxial Layer ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Threading Dislocation Density

Study of the initial stages of defect generation in ion-irradiated MgO at elevated temperatures using high-resolution X-ray diffraction

2015 ◽  
Vol 51 (3) ◽  
pp. 1456-1462 ◽  
Author(s):  
Diana Bachiller-Perea ◽  
Aurélien Debelle ◽  
Lionel Thomé ◽  
Jean-Paul Crocombette
Keyword(s):  
High Resolution ◽  
Elevated Temperatures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Defect Generation

Transformation of ferrihydrite to hematite: anin situinvestigation on the kinetics and mechanisms

2008 ◽  
Vol 72 (1) ◽  
pp. 217-220 ◽  
Author(s):  
H. P. Vu ◽  
S. Shaw ◽  
L. G. Benning
Keyword(s):  
High Resolution ◽  
Growth Mechanism ◽  
Elevated Temperatures ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Time Resolved ◽  
X Ray ◽  
Resolution Electron ◽  
Stage Process

AbstractThe kinetics and mechanisms of the transformation of 2-line ferrihydrite (FH) to hematite (HM), in the presence of Pb at elevated temperatures and high pH condition, were elucidated using synchrotron-based,in situenergy dispersive X-ray diffraction (EDXRD). The time-resolved diffraction data indicated that HM crystallization occurred via a two-stage process. Based on the EDXRD data, combined with high-resolution electron microscopic images, an aqueous-aided 2D growth mechanism is proposed for both HM crystallization stages.

Study of Dislocation Densities of Thick GaN Films

2014 ◽  
Vol 989-994 ◽  
pp. 387-390
Author(s):  
Yon Gan Li ◽  
Xiang Qian Xiu ◽  
Xue Mei Hua ◽  
Shi Ying Zhang ◽  
Shi Pu Gu ◽  
...  
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Screw Dislocation ◽  
Edge Dislocation ◽  
Thick Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dislocation Densities ◽  
Edge Dislocations

The dislocation density of GaN thick films has been measured by high-resolution X-ray diffraction. The results show that both the edge dislocations and the screw dislocation reduce with increasing the GaN thickness. And the edge dislocations have a larger fraction of the total dislocation densities, and the densities for the edge dislocation with increasing thickness reduce less in contrast with those for the screw dislocation.

Dislocation Arrangement in a Thick LEO GaN Film on Sapphire

1999 ◽  
Vol 595 ◽  
Author(s):  
Kathleen A. Dunn ◽  
Susan E. Babcock ◽  
Donald S. Stone ◽  
Richard J. Matyi ◽  
Ling Zhang ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Dislocation Density ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Burgers Vector ◽  
X Ray ◽  
The Third ◽  
Dislocation Arrangement ◽  
Gan Film

AbstractDiffraction-contrast TEM, focused probe electron diffraction, and high-resolution X-ray diffraction were used to characterize the dislocation arrangements in a 16[.proportional]m thick coalesced GaN film grown by MOVPE LEO. As is commonly observed, the threading dislocations that are duplicated from the template above the window bend toward (0001). At the coalescence plane they bend back to lie along [0001] and thread to the surface. In addition, three other sets of dislocations were observed. The first set consists of a wall of parallel dislocations lying in the coalescence plane and nearly parallel to the substrate, with Burgers vector (b) in the (0001) plane. The second set is comprised of rectangular loops with b = 1/3 [11 20] (perpendicular to the coalescence boundary) which originate in the coalescence boundary and extend laterally into the film on the (1 100). The third set of dislocations threads laterally through the film along the [1 100] bar axis with 1/3<11 20>-type Burgers vectors These sets result in a dislocation density of ∼109 cm−2. High resolution X-ray reciprocal space maps indicate wing tilt of ∼0.5°.

High Resolution X-ray Diffraction Analysis of GaN-Based Heterostructures Grown by OMVPE

1996 ◽  
Vol 449 ◽  
Author(s):  
M.S. Goorsky ◽  
A.Y. Polyakov ◽  
M. Skowronski ◽  
M. Shin ◽  
D.W. Greve
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Layer Thickness ◽  
Vapor Phase ◽  
Edge Dislocation ◽  
Initial Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Perfection ◽  
Misorientation Angles

ABSTRACTWe demonstrate the use of triple axis diffraction measurements, including Φ scans (in which the sample is rotated about an axis perpendicular to its surface) to assess the crystal perfection of wurtzite GaN layers on sapphire grown using different pre-nitridation growth treatments by or-ganometallic vapor phase epitaxy. The Φ scans determine the in-plane misorientation angles between the crystallites and hence provide information on the edge dislocation density. Using glancing incidence (1014) and (1015) reflections, we determined that the misorientation among the GaN crystallites decreases with increasing layer thickness and that the pre-nitridation conditions control the initial level of misorientation. Triple axis ω and ω-2θ scans around the (0002) reflection did not show a systematic trend with increasing layer thickness. However, layers grown without a pre-nitridation step tended to exhibit higher values of both mosaic spread and strain. The appropriate asymmetric reflections for GaN-based Φ scan measurements are determined using structure factor calculations, which are presented here.

Compositional and Structural Characterization of Heterostructure InGaN-Based Light-Emitting Diode by High Resolution X-Ray Diffraction

2012 ◽  
Vol 620 ◽  
pp. 22-27 ◽  
Author(s):  
Ahmad Hadi Ali ◽  
Ahmad Shuhaimi ◽  
Hassan Zainuriah ◽  
Yushamdan Yusof
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Structural Characterization ◽  
Light Emitting Diode ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
Light Emitting ◽  
X Ray ◽  
Multi Quantum Well

This paper focuses on the compositional and structural characterization of InGaN-based light-emitting diode (LED) using high resolution x-ray diffraction (HRXRD) system. The LED was epitaxially grown on Si (111) substrate that comprises of In0.11Ga0.89N multi-quantum-well (MQW) active layer. Phase analysis 2θ-scan proved the composition of GaN (0002) and (0004) at 34.63oand 72.98o, respectively. Rocking curveφ-scan showed six significant peaks of the hexagonal GaN structures with consistent angular gaps of ~60o. From x-ray rocking curve (XRC)ω-scan, screw and mix dislocation density is found as 2.85 × 109cm-2, while pure edge dislocation density is found as 2.23 × 1011cm-2.

High Resolution X-ray Diffraction and X-ray Topography Study of Gan on A12O3

1998 ◽  
Vol 512 ◽  
Author(s):  
J. Chaudhuri ◽  
M. Hooe Ng ◽  
D. D. Koleske ◽  
A. E. Wickenden ◽  
R. L. Henry
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Dislocation Density ◽  
Carrier Concentration ◽  
Vapor Phase ◽  
Metalorganic Vapor Phase Epitaxy ◽  
Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Reduced Pressure ◽  
X Ray

ABSTRACTHigh resolution x-ray diffraction and x-ray topography study of GaN thin films, grown on sapphire (00.1) substrate by reduced pressure metalorganic vapor phase epitaxy under various conditions, were performed. An attempt was made to correlate the mobility in films with similar carrier concentration with the strain and dislocation density. X-ray topography revealed the defects present in the film.

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