| dc.description.abstract | Silicon and germanium are the best semiconductor material choices for the integrated circuit for their material robustness and the fabrication process compatibility. Therefore, placement of SiGe thermoelectric microcoolers into integrated circuits to cool local hot spots is one of the promising, optimal solution to solve the heat problem in the future. Our research group has fabricated and explored the characteristics of thermal conductivity and electrical conductivity for 100 nm-wide poly-SiGe-pillars-array. Extensive experimental results show that 100 nm-wide, poly-SiGe nanopillars array with the Ge mole concentration of 24% possess, the estimated thermoelectric figure of merit (ZT) to up to 0.5 at 300 K.
In this thesis, we have fabricated poly-Si and poly-Si0.76Ge0.24 P-N pillars (diameter of 250 nm/ height of 1 μm) arrays with various of area size in 17 × 12 μm2, 37 × 32 μm2 and 56 × 52 μm2. P-N pillars were produced by ion implantation of Boron/1 × 1020 cm-3 as P-dopants and Phosphorus/1 × 1020 cm-3 for N-type donors, respectively. Following nickel evaporation and silicidation and rapid-thermal annealing, NiSi/NiSiGe nanocontacts were produced to connect the bottom of N- and P-pillars. Also aluminum top electrodes form by thermal evaporation of aluminum in conjunction with lift-off process were formed to bridge the top of pillars, the P-/N- pair SiGe nanopillar thermoelectric microcooler.
We systematically investigated effects of the array size and Ge concentration of poly-SiGe nanopillars on cooling capability at test conditions of the environmental temperature at 30, 60 and 90 oC as well as the driving current of 1, 3, 5, 7, 9 and 11 μA, respectively. Experimental results suggest that the poly-Si0.76Ge0.24 thermoelectric cooler with areas size of 37 × 32 µm2 possesses the best of the cooling capability with cooling temperature up to 15 oC for the condition of environmental temperature at 90 oC, and driving current at 11 μA.
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