Construction of a thermal conductivity measurement platform for bulk and thin film materials based on the 3-Omega technique

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Description

Nanostructured materials show signicant enhancement in the thermoelectric g-

ure of merit (zT) due to quantum connement eects. Improving the eciency of

thermoelectric devices allows for the development of better, more economical

Nanostructured materials show signicant enhancement in the thermoelectric g-

ure of merit (zT) due to quantum connement eects. Improving the eciency of

thermoelectric devices allows for the development of better, more economical waste

heat recovery systems. Such systems may be used as bottoming or co-generation

cycles in conjunction with conventional power cycles to recover some of the wasted

heat. Thermal conductivity measurement systems are an important part of the char-

acterization processes of thermoelectric materials. These systems must possess the

capability of accurately measuring the thermal conductivity of both bulk and thin-lm

samples at dierent ambient temperatures.

This paper discusses the construction, validation, and improvement of a thermal

conductivity measurement platform based on the 3-Omega technique. Room temperature

measurements of thermal conductivity done on control samples with known properties

such as undoped bulk silicon (Si), bulk gallium arsenide (GaAs), and silicon dioxide

(SiO2) thin lms yielded 150 W=m􀀀K, 50 W=m􀀀K, and 1:46 W=m􀀀K respectively.

These quantities were all within 8% of literature values. In addition, the thermal

conductivity of bulk SiO2 was measured as a function of temperature in a Helium-

4 cryostat from 75K to 250K. The results showed good agreement with literature

values that all fell within the error range of each measurement. The uncertainty in

the measurements ranged from 19% at 75K to 30% at 250K. Finally, the system

was used to measure the room temperature thermal conductivity of a nanocomposite

composed of cadmium selenide, CdSe, nanocrystals in an indium selenide, In2Se3,

matrix as a function of the concentration of In2Se3. The observed trend was in

qualitative agreement with the expected behavior.

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