# Regensburg 2004 – wissenschaftliches Programm

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# HL: Halbleiterphysik

## HL 51: Si/Ge

### HL 51.3: Vortrag

### Freitag, 12. März 2004, 12:00–12:15, H17

**Thermal Conductivity of Isotopically Enriched **^{28}**Si: Revisited** — •R. K. Kremer^{1}, M. Cardona^{1}, H.-J. Pohl^{2}, G. G. Devyatych^{3}, and P. G. Sennikov^{3} — ^{1}MPI für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — ^{2}VITCON Projectconsult GmbH, Otto-Schott-Str. 13, D-07745 Jena, — ^{3}Institute of Chemistry of Highly-Pure Substances, Russian Academy

The thermal conductivity of isotopically enriched ^{28}Si recently
has attracted particular
attention because of a claim of a 60% higher room-temperature
thermal conductivity of ^{28}Si
as compared to that of Si with a natural isotope mixture ^{nat}Si
[1].
It was argued, however,
that this result cannot be reconciled with theoretical estimates which
give,
at most, a 20%
increase. Because of the potential technological importance of a
significantly
larger thermal conductivity of isotopically pure samples of Si we have,
with
a steady-state heat-flow technique, redetermined the thermal conductivity
of the
previously measured samples and new single crystal samples of ^{28}Si
and ^{nat}Si
between 10K and 320K. To estimate and reduce the disturbing influence of
thermal
radiation losses at elevated temperature we have particularly taken care
to
utilize samples with identical geometrical dimensions.
Close to room-temperature we consistently find an increase in the thermal
conductivity of ^{28}Si with respect of that of ^{nat}Si of about
10 ± 2 %,
whereas the values of this enhancement below 100K are close to
that reported in ref. [1].

[1] T. Ruf *et al.*, Solid State Commun., **115**, 243 (2000).