Low Defect Density Bulk AlN Substrates for High Performance Electronics and Optoelectronics

2012 ◽  
Vol 717-720 ◽  
pp. 1287-1290 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Rafael Dalmau ◽  
Baxter Moody ◽  
H. Spalding Craft ◽  
Raoul Schlesser ◽  
...  
Keyword(s):  
Single Crystal ◽  
Basal Plane ◽  
High Performance ◽  
Defect Density ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Threading Dislocations ◽  
Crystalline Perfection ◽  
X Ray

Using the physical vapor transport (PVT) method, single crystal boules of AlN have been grown and wafers sliced from them have been characterized by synchrotron white beam X-ray topography (SWBXT) in conjunction with optical microscopy. X-ray topographs reveal that the wafers contain dislocations that are inhomogeneously distributed with densities varying from as low as 0 cm-2 to as high as 104 cm-2. Two types of dislocations have been identified: basal plane dislocations and threading dislocations, both having Burgers vectors of type 1/3<112-0> indicating that their origin is likely due to post-growth deformation. In some cases, the dislocations are arranged in low angle grain boundaries. However, large areas of the wafers are nearly dislocation-free and section X-ray topographs of these regions reveal the high crystalline perfection.

High Quality AlN Single Crystal Substrates for AlGaN-Based Devices

2018 ◽  
Vol 924 ◽  
pp. 923-926 ◽  
Author(s):  
Rafael Dalmau ◽  
H. Spalding Craft ◽  
Jeffrey Britt ◽  
Elizabeth Paisley ◽  
Baxter Moody ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Single Crystal ◽  
Basal Plane ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
High Magnification ◽  
High Quality ◽  
X Ray ◽  
Surface Finishes ◽  
Edge Dislocations

Aluminum nitride (AlN) single crystal boules were grown by physical vapor transport (PVT). Diameter expansion during boule growth, without the introduction of low angle grain boundaries (LAGB) around the boule periphery, was confirmed by crossed polarizer imaging, synchrotron white beam x-ray topography (SWBXT), and synchrotron monochromatic beam x-ray topography (SMBXT). The densities of basal plane dislocations (BPD) and threading edge dislocations (TED) averaged from high-magnification topographs of five regions of a high-quality substrate were 0 cm-2 and 992 cm-2, respectively. Substrates fabricated from AlN boules possessed excellent surface finishes suitable for epitaxy.

Structural Analysis of Dislocations in Highly Nitrogen-Doped 4H-SiC Substrates

2010 ◽  
Vol 645-648 ◽  
pp. 311-314 ◽  
Author(s):  
Masakazu Katsuno ◽  
Noboru Ohtani ◽  
Masashi Nakabayashi ◽  
Tatsuo Fujimoto ◽  
Hirokatsu Yashiro ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Basal Plane ◽  
Selective Etching ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
High Concentration ◽  
X Ray ◽  
Nitrogen Doped ◽  
Low Resistivity

Dislocations in highly nitrogen-doped (N > 1×1019 cm-3) low-resistivity ( < 10 mcm) 4H-SiC substrates were investigated by photoluminescence imaging, synchrotron X-ray topography, and defect selective etching using molten KOH. The behavior of dislocations is discussed particularly in terms of their glide motion in the presence of a high concentration of nitrogen. The results indicate that nitrogen impurities up to mid 1019 cm-3 concentration do not show any discernible influence on the glide behavior of basal plane dislocations (BPDs) in 4H-SiC crystals grown by physical vapor transport (PVT) method.

Sublimation Growth and Defect Characterization of AlN Single Crystals

2007 ◽  
Vol 1040 ◽  
Author(s):  
Shaoping Wang ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Zaiyuan Ren ◽  
Jung Han ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystal Growth ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Defect Characterization ◽  
Growth Technique ◽  
X Ray ◽  
Sublimation Growth ◽  
Growth Experiments

AbstractIn this paper, we report results from AlN single crystal growth experiments using a sublimation physical vapor transport growth technique. AlN single crystal boules up to 7mm in diameter were demonstrated. Characterization of polished AlN single crystal samples was carried out using various techniques, including synchrotron X-ray topography.

Observation of dislocations and their arrays in physical vapor transport-grown AlN single-crystal substrate by synchrotron X-ray topography

2019 ◽  
Vol 58 (SC) ◽  
pp. SCCB29 ◽  
Author(s):  
Yongzhao Yao ◽  
Yoshihiro Sugawara ◽  
Yukari Ishikawa ◽  
Narihito Okada ◽  
Kazuyuki Tadatomo ◽  
...  
Keyword(s):  
Single Crystal ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Single Crystal Substrate ◽  
X Ray ◽  
Crystal Substrate

X-Ray Topographic Studies of Defects in PVT 6H-SiC Substrates and Epitaxial 6H-SiC Thin Films

1994 ◽  
Vol 339 ◽  
Author(s):  
S. Wang ◽  
M. Dudley ◽  
C. H. Carter ◽  
H. S. Kong
Keyword(s):  
Thin Films ◽  
Basal Plane ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Epitaxial Thin Films ◽  
Defect Structures ◽  
Screw Dislocations ◽  
X Ray ◽  
Back Reflection ◽  
White Beam

ABSTRACTSynchrotron white beam X-ray topography has been used to characterize defect structures in (0001) 6H-SiC substrates grown by the sublimation physical vapor transport (PVT) technique as well as in 6H-SiC epitaxial thin films grown on these substrates. Defects revealed in 6H-SiC substrates include super screw dislocations and basal plane dislocations. It has been found that back-reflection topographs are particularly suitable for imaging such super screw dislocations as well as basal plane dislocations whenever transmission topography is not applicable. Epitaxial 6H-SiC thin films grown on such (0001) substrates (tilted a few degrees towards the a-axis) were also examined by using surface sensitive grazing Bragg-Laue topography. It has been shown that super screw dislocations were replicated in the epitaxial thin films but no basal plane dislocations were revealed in the thin films. Results from various topographic techniques are discussed.

150 mm 4H-SiC Substrate with Low Defect Density

2016 ◽  
Vol 858 ◽  
pp. 41-44
Author(s):  
Yu Qiang Gao ◽  
Hong Yan Zhang ◽  
Yan Min Zong ◽  
Huan Huan Wang ◽  
Jian Qiu Guo ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Dislocation Density ◽  
Late Stage ◽  
Defect Density ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Base Plane ◽  
High Quality ◽  
X Ray ◽  
Screw Dislocation Density

150 mm diameter 4H-SiC boules were grown by the physical vapor transport (PVT) method. Synchrotron white beam X-ray topography (SWBXT) was carried out to investigate the distribution of defects in axial slices cut from the boule. It was found that an increase of dislocations and micropipes was mainly induced by inclusions. After eliminating these inclusions, which were formed in the mid to late stage of the crystal growth, both the screw dislocation density and base plane dislocation density could be decreased down to a magnitude of 102 cm-2, which is comparable to that of high quality 100 mm diameter SiC substrates.

Investigation of Low Angle Grain Boundaries in Hexagonal Silicon Carbide

2006 ◽  
Vol 955 ◽  
Author(s):  
Yi Chen ◽  
Hui Chen ◽  
Ning Zhang ◽  
Michael Dudley ◽  
Ronghui Ma
Keyword(s):  
Silicon Carbide ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Vapor Transport ◽  
Threading Dislocations ◽  
Prismatic Plane ◽  
Screw Dislocations ◽  
X Ray ◽  
Edge Dislocations ◽  
Dislocation Walls

ABSTRACTInteraction between basal plane dislocations and single or well-spaced threading dislocations is discussed based on synchrotron white beam X-ray topographic studies carried out on physical vapor transport grown hexagonal silicon carbide single crystals. The basal plane dislocations are able to cut through single or well-spaced threading edge dislocations even if the formation of kinks/jogs is energetically unfavorable while threading screw dislocations were mostly observed to act as effective pinning points. However, basal plane dislocations can sometimes cut through a threading screw dislocation, forming a superjog and which subsequently migrates on the prismatic plane via a cross-slip process. Threading edge dislocation walls act as obstacles for the glide of basal plane dislocations and the mechanism by which this occurs is discussed. The character of low angle grain boundaries and their dislocation content are discussed.

Formation Mechanism of Stacking Faults in PVT 4H-SiC Created by Deflection of Threading Dislocations with Burgers Vector c+a

2011 ◽  
Vol 679-680 ◽  
pp. 269-272 ◽  
Author(s):  
Michael Dudley ◽  
Huan Huan Wang ◽  
Fang Zhen Wu ◽  
Sha Yan Byrapa ◽  
Balaji Raghothamachar ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Growth Conditions ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Threading Dislocations ◽  
Stress Growth ◽  
Burgers Vector ◽  
X Ray ◽  
Dislocation Behavior ◽  
New Generation

Synchrotron White Beam X-ray Topography studies are presented of dislocation behavior and interactions in a new generation of seventy-six millimeter diameter, 4H-SiC wafers grown using Physical Vapor Transport under specially designed low stress conditions. Such low stress growth conditions have enabled reductions of dislocation density by two or three orders of magnitude compared to the lowest previously reported levels [1]. In this paper, detailed topography analysis will be presented of the deflection of threading dislocations with Burgers vectors of c and c+a onto the basal plane leading to reductions of the density of such dislocations down to levels of ~187 cm-2. The deflection of the latter type of dislocations produces complex faulted defect configurations and models for their creation are presented and discussed.

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