Origin of ring defects in high In content green InGaN/GaN MQW: An Ultrasonic Force Microscopy Study

2005 ◽  
Vol 10 ◽  
Author(s):  
F. Shahedipour-Sandvik ◽  
M. Jamil ◽  
K. Topol ◽  
J. R. Grandusky ◽  
Kathleen A Dunn ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Barrier Layer ◽  
Chemical Etching ◽  
Microscopy Study ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Green Led ◽  
Appreciable Variation

Observation of GaN-based islands surrounded by V-defects in the barrier layer of green LED is reported for InGaN MQWs deposited under no hydrogen or at growth temperatures of less than 800°C. Nanoscale mechanical properties of the areas enclosed and outside of the ring defects does not show any appreciable variation as measured by UFM. Chemical etching of the MQW structure in addition to cross-sectional TEM analysis ruled out the possibility of growth of inversion domains of N-polar GaN in a Ga-polar GaN matrix.

INVESTIGATION OF Ta/Ni–Al INTEGRATED FILM USED AS A DIFFUSION BARRIER LAYER BETWEEN Cu AND Si

2014 ◽  
Vol 21 (06) ◽  
pp. 1450079 ◽  
Author(s):  
LIM YANG ◽  
SHI JIE WANG ◽  
JI CHUAN HUO ◽  
XIAO HONG LI ◽  
JIAN XIN GUO ◽  
...  
Keyword(s):  
Barrier Layer ◽  
Diffusion Barrier ◽  
High Vacuum ◽  
Annealed Sample ◽  
Ultra High Vacuum ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Si Substrates ◽  
Transmission Electron ◽  
Xrd Patterns

Ta (3.3 nm)/ Ni – Al (3.3 nm) integrated films deposited on Si substrates by magnetron sputtering, annealed at various temperatures in a ultra-high vacuum, have been studied as diffusion barrier layers between Cu and Si for application in Cu interconnection. The images of transmission electron microscopy (TEM) prove that the cross-sectional interfaces of Cu / Ta / Ni – Al / Si sample annealed at 600°C are clear and sharp. No Cu –silicide peaks can be found from the X-ray diffraction (XRD) patterns of the 850°C annealed sample, but the sheet resistance of the sample increases abruptly. Moreover, large grooves are found from the image of atomic force microscopy (AFM) for the 850°C annealed sample, implying the failure of the diffusion barrier. The integrated Ta / Ni – Al barrier layer retains thermally stable nature up to at least 800°C, indicating that the Ta / Ni – Al integrated film is an excellent diffusion barrier between Cu and Si .

Effect of thermo-mechanical refining pressure on the properties of wood fibers as measured by nanoindentation and atomic force microscopy

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 230-236 ◽  
Author(s):  
Cheng Xing ◽  
Siqun Wang ◽  
George M. Pharr ◽  
Leslie H. Groom
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Loblolly Pine ◽  
Cell Walls ◽  
Physical And Mechanical Properties ◽  
Wood Fibers ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Mechanical Refining ◽  
Atomic Force

Abstract Refined wood fibers of a 54-year-old loblolly pine (Pinus taeda L.) mature wood were investigated by nanoindentation and atomic force microscopy (AFM). The effect of steam pressure, in the range of 2–18 bar, during thermo-mechanical refining was investigated and the nano-mechanical properties and nano- or micro-level damages of the cell wall were evaluated. The results indicate that refining pressure has important effects on the physical and mechanical properties of refined fibers. No obvious damage was observed in the cell walls at pressures between 2 and 4 bar. Nano-cracks (most less than 500 nm in width) were found in fibers at pressures in the range of 6–12 bar, and micro-cracks (more than 5 μm in width) were found in fibers subjected to pressures of 14 and 18 bar. The damages caused at higher pressures were more severe in layers close to the lumen than on the fiber surfaces. Under special circumstances, the S3 layer was heavily damaged. The natural shape of the cross sectional dimensions of the cell walls was not changed at lower pressures (2 and 4 bar), but, as pressure was increased, the fibers tended to collapse. At pressures around 18 bar, the lumina were augmented again. The nano-mechanical properties in terms of elastic modulus and hardness were obviously decreased, while nanoindentation creep increased with refining pressure.

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