Thin Film Boron Doped Polycrystalline Silicon/sub70%/-germanium/sub30%/ For Thermopiles

Abstract

CMOS-compatible thermopiles can be made by using the available polysilicon layer and aluminium layer as thermocouple. SiGe would however offer a better performance than silicon, mostly due to the much lower thermal conductivity [4], while it maintains CMOS compatibility. The figure of merit of a highly boron doped (about 1020 at/cm3) thin film poly-Si70%Ge30% layer deposited by ULPCVD is reported. The figure of merit is measured with a dedicated structure: the Seebeck coefficient is f 75 pV/K, the thermal conductivity is f 4.8 W/mK and the electrical resistivity is 2 3 p R m . The figure of merit is then calculated to be z = 50.10-6/K.

Fabrication of Poly-Ge-Based Thermopiles on Plastic

“…Germanium, on the other hand, can be processed at temperatures far below that of silicon and the junction sensitivity remains high. Alloys of Si-Ge are suitable candidates for making high-performance thermocouple-based devices [9]. In this paper, we report the successful fabrication of Ge-Al thermocouples at processing temperatures lower than 175 C. The formation of polycrystalline-Ge is achieved using Cu-induced crystallization in the presence of an external compressive stress.…”