Revealing Low Thermal Conductivity of Germanium Tin Semiconductor at Room Temperature

The low thermal conductivity of a material is a key essential parameter for its potential application in high-performance thermoelectric devices. Unprecedently low thermal conductivity of germanium tin (Ge1-xSnx) semiconductor thin film is experimentally obtained at room temperature. The thermal conductivity decreases with increasing Sn concentration in the relaxed Ge1-xSnx binary alloy, which is explained mainly by increasing the interatomic distance between atoms via alloying. A pronounced decrease of thermal conductivity, by over 20 times, from 58 W m-1K-1 in Ge to approximate to 2.5 W m-1K-1 in relaxed Ge1-xSnx, with Sn content up to 9% is observed. This thermal conductivity is just approximate to 2 times higher than that of the state-of-the-art thermoelectric material, Bismuth Selenium Telluride. Ge1-xSnx, in contrast, is a non-toxic Group-IV semiconductor material, that is epitaxially grown on a standard silicon wafer up to 300 mm diameter using the semiconductor industry standard epitaxial growth technique. As a result, it can lead to the creation of a long-awaited high-performance low-cost thermoelectric energy generator for room-temperature applications in human's daily life and would make a substantial contribution toward global efforts in CO2 emission-free and green electricity generation. Unprecedently low thermal conductivity of germanium tin (Ge1-xSnx) semiconductor thin film is experimentally obtained at room temperature via microfabrication. The thermal conductivity decreases with increasing Sn concentration in the relaxed Ge1-xSnx binary alloy, which is explained mainly by increasing the interatomic distance between atoms via alloying. A pronounced decrease of thermal conductivity, by over 20 times, from 58 W m-1K-1 in Ge to approximate to 2.5 W m-1K-1 in relaxed Ge1-xSnx, with Sn content up to 9% is observed.image