V - Positron Annihilation in Halle
V - Positron Annihilation in Halle
V - Positron Annihilation in Halle
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Diffusion of Cu <strong>in</strong> GaAs<br />
280<br />
• <strong>Positron</strong> experiment:<br />
• 30 nm Cu-layer deposited by<br />
•<br />
evaporation evapo at o<br />
Anneal<strong>in</strong>g at 1100°C (under def<strong>in</strong>ed<br />
270<br />
•<br />
•<br />
As-pressure) for Cu <strong>in</strong>-diffusion<br />
Quench<strong>in</strong>g to RT<br />
then anneal<strong>in</strong>g with grow<strong>in</strong>g<br />
260<br />
•<br />
temperature<br />
<strong>Positron</strong> lifetime measurement<br />
250<br />
• Cu is completely solved at 1100°C<br />
• But it is oversaturated at RT<br />
• Precipitation starts very slowly (slow<br />
diffusion)<br />
• However: at elevated temperatures – diffusion<br />
240<br />
bbecomes faster: f out-diffusion diff i process<br />
• Result: formation of vacancy-type defects<br />
when out-diffusion starts<br />
• Not compatible with ith current c rrent diffusion diff sion models<br />
230<br />
Mart<strong>in</strong>-Luther-Universität <strong>Halle</strong><br />
averrage<br />
positrron<br />
lifetimee<br />
(ps)<br />
400 K<br />
500 K<br />
550 K<br />
600 K<br />
650 K<br />
700 K<br />
750 K<br />
800 K<br />
850 K<br />
900 K<br />
0 100 200 300 400 500<br />
measurement temperature (K)
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