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Keywords:

thermoelectric, polycrystalline silicon-germanium, figure of merit, Thermal conductance, micromachining, thermopiles, Science & Technology, Technology, Engineering, Electrical & Electronic, Instruments & Instrumentation, Engineering, 0906 Electrical and Electronic Engineering, 0912 Materials Engineering, 0913 Mechanical Engineering, Nanoscience & Nanotechnology, 4008 Electrical engineering, 4009 Electronics, sensors and digital hardware, 4017 Mechanical engineering

Abstract:

CMOS-compatible thermopiles can be made by using the available polysilicon layer and aluminium layer as a thermocouple. SiGe would, however, offer a better performance than silicon, mostly due to its much lower thermal conductivity, while it maintains CMOS compatibility. The figure of merit of a highly boron doped (about 1020 atoms cm-3) thin-film poly-Si70%Ge30% layer deposited by ultra-low-pressure chemical vapour deposition (ULPCVD) is reported. The figure of merit is measured with a dedicated structure: the Seebeck coefficient is ± 75 μV K-1, the thermal conductivity is ±4.8 W mK-1 and the electrical resistivity is 23 μΩ m. The figure of merit is then calculated to be z≈50×10-6 K-1.