Determination of edge-component Burgers vector of threading dislocations in GaN crystal by using Raman mapping

2018 ◽  
Vol 11 (11) ◽  
pp. 111001 ◽  
Author(s):  
Nobuhiko Kokubo ◽  
Yosuke Tsunooka ◽  
Fumihiro Fujie ◽  
Junji Ohara ◽  
Shoichi Onda ◽  
...  
Keyword(s):  
Threading Dislocations ◽  
Raman Mapping ◽  
Burgers Vector ◽  
Edge Component ◽  
Gan Crystal

Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

Simulation of Forescattered Electron Channeling Contrast Imaging of Threading Dislocations Penetrating SiC Surfaces

2008 ◽  
Vol 1068 ◽  
Author(s):  
Mark E. Twigg ◽  
Yoosuf N. Picard ◽  
Joshua D. Caldwell ◽  
Charles R. Eddy ◽  
Philip G. Neudeck ◽  
...  
Keyword(s):  
Primary Source ◽  
Threading Dislocations ◽  
Contrast Imaging ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
Image Intensity ◽  
Electron Channeling ◽  
Kikuchi Line ◽  
Simulated Images

ABSTRACTThe interpretation of ECCI images in the forescattered geometry presents a more complex diffraction configuration than that encountered in the backscattered geometry. Determining the Kikuchi line that is the primary source of image intensity often requires more than simple inspection of the electron-channeling pattern. This problem can be addressed, however, by comparing recorded ECCI images of threading screw dislocations in 4H-SiC with simulated images. An ECCI image of this dislocation is found to give the orientation of the dominant Kikuchi line, greatly simplifying the determination of the diffraction simulation. In addition, computed images of threading screw dislocations in 4H-SiC were found to exhibit channeling contrast essentially identical to that obtained experimentally by ECCI and allowing determination of the dislocation Burgers vector.

scholarly journals Dislocation Arrangement in a Thick LEO GaN Film on Sapphire

2000 ◽  
Vol 5 (S1) ◽  
pp. 97-103
Author(s):  
Kathleen A. Dunn ◽  
Susan E. Babcock ◽  
Donald S. Stone ◽  
Richard J. Matyi ◽  
Ling Zhang ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Burgers Vector ◽  
X Ray ◽  
The Third ◽  
Dislocation Arrangement ◽  
Image Position ◽  
Gan Film

Diffraction-contrast TEM, focused probe electron diffraction, and high-resolution X-ray diffraction were used to characterize the dislocation arrangements in a 16µm 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 [110] (perpendicular to the coalescence boundary) which originate in the coalescence boundary and extend laterally into the film on the (100). The third set of dislocations threads laterally through the film along the [100] bar axis with 1/3<110>-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 ∼0.5º.

Growth defects in GaN films on sapphire: The probable origin of threading dislocations

1996 ◽  
Vol 11 (3) ◽  
pp. 580-592 ◽  
Author(s):  
X. J. Ning ◽  
F. R. Chien ◽  
P. Pirouz ◽  
J. W. Yang ◽  
M. Asif Khan
Keyword(s):  
Substrate Surface ◽  
Film Surface ◽  
Biaxial Compression ◽  
Threading Dislocations ◽  
Burgers Vector ◽  
Growth Defects ◽  
Surface Steps ◽  
Probable Origin ◽  
Film Substrate ◽  
Gan Buffer Layer

Single crystal GaN films with a wurtzite structure were grown on the basal plane of sapphire. A high density of threading dislocations parallel to the c-axis crossed the film from the interface to the film surface. They were found to have a predominantly edge character with a Burgers vector. In addition, dislocation hal-loops, elongated along the c-axis of GaN, were also found on the prism planes. These dislocations had a mostly screw character with a [0001] Burgers vector. Substrate surface steps with a height of were found to be accommodated by localized elastic bending of GaN (0001)GaN planes in the vicinity of the film/substrate interface. Observations show that the region of the film, with a thickness of ∼100 nm, adjacent to the interface is highly defective. This region is thought to correspond to the low-temperature GaN “buffer” layer which is initially grown on the sapphire substrate. Based on the experimental observations, a model for the formation of the majority threading dislocations in the film is proposed. The analysis of the results leads us to conclude that the film is under residual biaxial compression.

Determination of the Sense of Burgers Vector by Plane-Wave X-ray Topography

1983 ◽  
Vol 22 (Part 2, No. 3) ◽  
pp. L151-L153
Author(s):  
Kohtaro Ishida ◽  
Yoshinori Kobayashi ◽  
Hiroyuki Katoh ◽  
Satio Takagi
Keyword(s):  
Plane Wave ◽  
Burgers Vector ◽  
X Ray

Weak-Beam Thickness-Fringe Contrast Analysis of Defects in GaN Pyramids

1999 ◽  
Vol 5 (S2) ◽  
pp. 736-737
Author(s):  
Zhigang Mao ◽  
Stuart McKeraan ◽  
C. Barry Carter ◽  
Wei Yang ◽  
Scott A. McPherson
Keyword(s):  
Basal Plane ◽  
Threading Dislocations ◽  
Prism Plane ◽  
Fringe Contrast ◽  
Burgers Vector ◽  
Weak Beam ◽  
Contrast Analysis ◽  
Half Loop ◽  
Beam Thickness ◽  
Hcp Structure

The possible dislocations and slip systems in the wurtzite structure are the same as in hcp structure [1]. The Burgers vectors of these dislocations are . The dislocations can lie on either the (0001) basal plane or prism planes. The dislocations lie on pyramidal planes. TEM studies have revealed that there are predominately three types of dislocations in a wurtzite GaN epilayer which has not been grown by selective overgrowth (e. g. [2, 3]). The majority of the dislocations are threading dislocations with Burgers vector which appear randomly in the epilayer, they result from the growth errors during the growth process. The other two types of dislocation are halflpops with a [0001] or Burgers vector. The [0001] dislocation half-loop lies on the prism plane and the dislocation half-loop lies on the (0001) basal plane which usually appears near the epilayer/substrate interface.

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