Thermal conductivity, dislocation density and GaN device design

2006 ◽  
Vol 40 (4-6) ◽  
pp. 338-342 ◽  
Author(s):  
C. Mion ◽  
J.F. Muth ◽  
Edward A. Preble ◽  
Drew Hanser
Keyword(s):  
Thermal Conductivity ◽  
Dislocation Density ◽  
Device Design

Single-Crystal Aluminum Nitride Substrate Preparation from Bulk Crystals

2001 ◽  
Vol 680 ◽  
Author(s):  
J. Carlos Rojo ◽  
Leo J. Schowalter ◽  
Kenneth Morgan ◽  
Doru I. Florescu ◽  
Fred H. Pollak ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Dislocation Density ◽  
Single Crystal ◽  
High Strain ◽  
Bulk Crystals ◽  
Scanning Thermal Microscopy ◽  
Substrate Preparation ◽  
X Ray ◽  
Differential Expansion

ABSTRACTLarge (15mm diameter) single-crystal AlN boules have been prepared using sublimationrecondensation growth. X-ray topography shows that the dislocation density averages less than 103 cm2 in some of the substrates but also that the dislocations are not uniformly distributed. Also, strain due to the differential expansion with the crucible walls seems to cause severe cracking in the periphery of the crystal and high-strain regions. Thermal analysis using the Scanning Thermal Microscopy (SThM) reveals a thermal conductivity of 3.4 ± 0.2 W/K-cm, which is the largest value ever reported for AlN.

Accurate dependence of gallium nitride thermal conductivity on dislocation density

2006 ◽  
Vol 89 (9) ◽  
pp. 092123 ◽  
Author(s):  
C. Mion ◽  
J. F. Muth ◽  
E. A. Preble ◽  
D. Hanser
Keyword(s):  
Thermal Conductivity ◽  
Gallium Nitride ◽  
Dislocation Density

Increased thermal conductivity of free-standing low-dislocation-density GaN films

2005 ◽  
Vol 202 (12) ◽  
pp. R135-R137 ◽  
Author(s):  
Weili Liu ◽  
Alexander A. Balandin ◽  
Changho Lee ◽  
Hae-Yong Lee
Keyword(s):  
Thermal Conductivity ◽  
Dislocation Density ◽  
Free Standing ◽  
Low Dislocation Density

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

HARDNESS AND THERMAL CONDUCTIVITY OF As-Se-Te CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-931-C4-934 ◽  
Author(s):  
M. F. Kotkata ◽  
M.B. El-den
Keyword(s):  
Thermal Conductivity ◽  
Chalcogenide Glasses
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