Interaction of Dislocations in Strained Metal Films

1
Interaction of Dislocations in Strained Metal
Films
Juan de la Figuera, Karsten Pohl, Andreas K.
Schmid, Norm C. Bartelt and Robert Q. Hwang
Sandia National Laboratories
Funding DOE-AC04-94AL85000 Fulbright and
MEC/Spain PB96-0652
2
Misfit dislocations in hexagonal substrates
3
Networks of misfit dislocations template
patterns?
Au(111)
3ML Cu/ Ru(0001)
50nm
4
Misfit Shockley partial dislocations
Also known as domain walls and solitons
2ML Cu/Ru(0001)
-5.5 misfit
1ML Au/Ru(0001)
6.6 misfit
5
1ML Cu on Ru(0001)

• Films annealed to 500C are pseudomorphic with Ru
• Metastable misfit dislocations can be produce at
  RT by supersaturating the 2D adatom gas on top of
  the film

HCP
HCP
FCC
6
Supersaturated 1ML Cu/Ru
1500Å
7
Structure of misfit dislocations in Cu/Ru
8
Glide vs Climb for dislocations
Climb
Glide
Climb
Glide
9
Climb of threading dislocations
10
Glide of dislocations
11
Bending of dislocations
12
Different dislocations bending
13
Theory of a bent dislocation
14
Expected amplitude from thermal fluctuations
15
Relation between amplitude and stifness
Using the observed value of 12 Å for a
dislocation which is 430 Å long, we obtain
? 30 meV/Å
16
Frenkel-Kontorova model

• No other experimental data available
• Comparison with Frenkel-Kontorova model fitted to
  Au(111)

? lt150meV/Å
17
Summary

• Oscillating vibrations observed in Cu/Ru(0001)
• The source of the vibrations is thermal
• The amplitude can be related with the stiffness
  of the dislocations