Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 107: Poster: Emerging oxide semiconductors / Oxides other than ZnO and its relatives
HL 107.16: Poster
Donnerstag, 3. April 2014, 17:00–20:00, P1
3ω thermal conductivity measurements of β−Ga2O3 bulk crystal — •Martin Handwerg, Christine Bülow, Rüdiger Mitdank, and Saskia F. Fischer — Neue Materialien, Institut f. Physik, Humboldt-Universität zu Berlin, D-10099 Berlin
Ga2O3 belongs to the group of transparent conducting oxides with scarce information about thermal and electric properties. Here, the thermal conductivity λ of a β−Ga2O3 bulk-crystal is determined by using the 3ω-method. Therefore, a lineheater in 4 point geometry is placed above the crystal. An AC-heating current causes an increase of the temperature followed by an increasing heater resistance. The rising temperature generates an AC-signal with three times the frequency of the input current. This 3ω-voltage depends on the input frequency, which is related to the thermal penetration depth. In a common measurement setup a thermal penetration depth up to 1 mm below the heater can be reached. The thermal conductivity is calcuated by the slope of U3ω(ln f) and the heater parameters [1].
As a result of the U3ω measurements of an 1 mm thick Ga2O3 [100] crystal the thermal conductivity was determined for a temperature interval between 4.2 K and 300 K. The temperature-dependent behaviour of the thermal conductivity fits with the theoretic explanations for insulators. Comparing the U3ω-method for thermal conductivity measurments at room temperature with optical methods there are consistent results with λ=13.6 Wm−1K−1 .
[1] D. Cahill et al, Physical Review B 35 (1987)