Control of thermal boundary resistance by increasing Ge ratio in nanocomposite with MnSi1.7 and SiGe

Thermal boundary resistance (TBR) was controlled by changing the Ge ratio in a MnSi1.7-based nanocomposite with SiGe to investigate the effects of TBR on thermal transport. We demonstrated a continuous reduction of thermal conductivity with the Ge ratio down to 1.2 W/Km, which is less than the minimum thermal conductivity of MnSi1.7, even in granular structures: practical forms of thermoelectric (TE) technologies. The TBR between MnSi1.7 and SiGe was estimated quantitatively in multilayered structures to be as high as 5.6 × 10−9 m2 K/W and a detailed analysis suggests that 20%–30% of the thermal conductivity reduction is attributed to the TBR in granular structures. Our results shed light on the importance of controlling TBR in TE material design towards a widespread use of TE technologies, instead of utilizing rare materials or uneconomical nanostructures.