Scientists are exploring new materials that can efficiently capture and convert waste heat into electricity, even at low temperatures like body heat or chip temperatures. They are focusing on GeSn alloys, a mix of Germanium (Ge) and Tin (Sn), which are grown on Silicon wafers. These materials are promising for "green" computing and low-power Internet of Things devices.

GeSn alloys have a much lower thermal conductivity than pure Germanium, which means they can better convert heat into electricity. The thermal conductivity of these alloys drops dramatically from 55 W/(m·K) for pure Ge to just 4 W/(m·K) for Ge0.88Sn0.12, meaning they retain heat better and are more efficient for thermoelectric applications.

Researchers measured the thermal properties of these alloys using a special method called the "3ω-method." This method involves using metallic stripes on the material to generate heat and measure the resulting temperature changes. They found that the thermal conductivity of GeSn alloys depends on the amount of Tin and the thickness of the layers.

The results showed that GeSn alloys can achieve similar energy harvesting capabilities to SiGe alloys but at much lower temperatures, between 20°C and 100°C, which are typical for many electronic devices. This makes GeSn alloys very promising for integration into existing silicon-based technology (CMOS), potentially reducing energy consumption and cooling needs in electronic devices.

In summary, GeSn alloys are a potential game-changer for thermoelectric materials used in electronics, offering a greener and more efficient way to manage and utilize waste heat, especially at lower temperatures suitable for everyday electronic devices and wearable technology.