ICT2014 Abstracts

Due to new research efforts in the field of thermo electrics with a focus on size effects, there is a growing need for measurement setups dedicated to samples with small geometrical dimensions like thin films and nanowires with considerably different physical properties than bulk material. The characterization of these samples is important to learn more about their structure and conduction mechanism but also important for technical applications e.g. in the semiconductor industry.

We report on new developments in the field of characterization systems. The first one is a chip based system to simultaneous measure the electrical and thermal conductivity[1], the Seebeck Coefficient and the Hall Constant of a thin film sample in the temperature range from liquid nitrogen up to 350°C. Due to the nearly simultaneous measurement at only one sample, errors caused by different sample compositions, different sample geometries (thickness) and different heat profiles can be avoided. The system consists of two main parts, a structured Si-wafer and a suitable measurement setup. The sample depostition and handling is kept easy and optimized to meet a very borad range of users.

The second system is a modified laser Flash setup that uses the Transient Thermoreflectance Method which enables the measurement of the thermal conductivity on nanometer scaled thin films with high accuracy. On various application examples it can be proved that the thermal conductivity is strongly dependent on the thickness of the material. The thermal conductivity decreases with decreasing sample thickness. The thermal conductivity of the bulk material is much higher by one or two orders of magnitude.

References:  [1] F. Voelklein et. al., Phys. Status Solidi A 210, No. 1, 106–118 (2013)