The effect of YSi₂ nanoinclusion on the thermoelectric properties of p‐type SiGe alloy

Abstract

Corresponding author: email psupree@kk.ac.th, Phone: þ66 87 373 11 22, Fax: þ66 43 203 359 In this research, the p-type Si 80 Ge 20 B 3 alloys composited with YSi 2 nanoinclusions were fabricated by melting spinning and then, spark plasma sintering. The metallic Y was chosen as the source of YSi 2 nanoparticles. It was found that the fully dense nanocomposites were formed with the homogeneous distribution of YSi 2 nanoinclusions in the SiGe matrix. The thermoelectric measurement showed that YSi 2 addition reduces the electrical conductivity but increases the Seebeck coefficient, which was attributed to the decrease in carrier concentration. The thermal conductivity was suppressed for the composite SiGe-1.4%Y, which made this composition to exhibit the largest thermoelectric figure-of-merit (ZT) of 0.52. Figure-of-merit (ZT) and microstructure of the SiGe-x%Y SiGe-1.4%Y.

Methodology of Thermoelectric Power Factor Enhancement by Nanoscale Thermal Management in Bulk SiGe Composites

“…SiGeAu samples exhibited a 1.4 times higher S value and the resultant twice higher S 2 σ at the same σ than SiGe samples without Au. Furthermore, as shown in Figure d where previously reported results of single crystals and polycrystals of SiGe with various Ge fraction (10–80%), RTG SiGe, nanostructured SiGe, modulation-doped SiGe, and SiGe-YSi 2 nanocomposites are plotted, ,− it was found that in our present SiGeAu samples where just a small amount of Au (2 at. %) was introduced into the SiGe material, the highest S 2 σ value of 22 μW cm –1 K –2 at RT was achieved among many other SiGe-related materials that have ever been reported.…”

“…There are many reports of SiGe-based thermoelectric materials. It is known that SiGe exhibits lower κ (∼6 W m –1 K –1 ) due to alloy scattering than bulk Si. ,,− As for the studies about the SiGe-based films containing Au, some reported the anomalous enhancement of S 2 σ, , and others reported no enhancement of S 2 σ . This difference is scientifically and practically interesting, and it comes from the unclearness of S 2 σ enhancement mechanism.…”

High Power Factor vs. High zT—A Review of Thermoelectric Materials for High-Temperature Application

“…In SiGe alloys, the large difference in the mean free path between electron (approximately 5 nm) and phonon (approximately 200–300 nm) contributions leads to a strong influence of nanostructuring in a range of 10–100 nm, which reduces the thermal conductivity without significantly reducing the electrical conductivity [ 182 ]. Therefore, nanostructuring [ 183 , 184 , 185 ] and the use of nanoinclusions [ 184 , 186 , 187 , 188 , 189 ] are common strategies to further improve the thermoelectric properties of SiGe alloys. For preparation of SiGe alloys, solid-state ball milling [ 180 , 183 , 186 , 187 , 190 , 191 , 192 , 193 , 194 ] or melt spinning (MS) [ 182 , 189 ] in combination with subsequent SPS are commonly used.…”

“…Therefore, nanostructuring [ 183 , 184 , 185 ] and the use of nanoinclusions [ 184 , 186 , 187 , 188 , 189 ] are common strategies to further improve the thermoelectric properties of SiGe alloys. For preparation of SiGe alloys, solid-state ball milling [ 180 , 183 , 186 , 187 , 190 , 191 , 192 , 193 , 194 ] or melt spinning (MS) [ 182 , 189 ] in combination with subsequent SPS are commonly used. Bathula et al [ 192 ] reported a peak zT of 1.72 with a power factor of 28.7 W cm −1 K −2 for n -doped Si 80 Ge 20 with SiC nanoinclusions.…”

Temperature dependences of thermoelectric properties of bulk SiGeAu composites

“…Silicon germanium (SiGe) has been attracted attention as one of the promising thermoelectric materials due to its non-toxicity, chemical stability, and high ZT in the high temperature range [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. However, SiGe does not have high ZT near room temperature (RT).…”