Thermoelectric properties of thin-film germanium-based layers

Abstract

Purpose – The purpose of this paper is to determine the thermoelectric properties of the germanium-based thin films and selecting the most suitable ones for fabrication of micrognerators. Design/methodology/approach – The germanium layers were deposited by low pressure magnetron sputtering method, in the pressure of 10−3/104 mbar range. The amount of dopants (germanium or vanadium) was changed in a limited extent. The influence of such changes on the layers output properties was studied. Post-processing heat treatment at temperature below 823 K was applied to activate the layers. It leads to improve the electrical and thermoelectrical performance. Findings – The special attention was paid to the power factor (PF = S2/ρ) of the layers. To estimate power factor (PF) electrical resistivity (ρ) and Seebeck coefficient (S) were determined. The achieved Seebeck coefficient value was 185 Volt/Kelvin (μV/K) for germanium doped with vanadium (Ge:V1.15) and 225 μV/K for germanium doped with gold(Ge:Au3.13) layers at room temperature. After activation process, the PF reached a value of 2.5 × 10−4 W/m · K2 for the Ge:Au3.13 and 1.1 × 10−4 W/m · K2 for the Ge:V1.15 layers. Originality/value – The fabricated thermoelectric layers can be thermally annealed in temperature up to 823 K in the air and in 1,023 K under a nitrogen atmosphere. This enables integration of thin layers with thick-film technology. Corning glass or low temperature cofired ceramic was used as a substrate.