Holey and Unholey Semiconductors

TLDR

Cooling electronic devices often requires thermodynamic cycles, but thermoelectric materials use the Peltier effect where heat is carried by charge carriers rather than the lattice, offering solid‑state refrigeration yet historically limited by low efficiency. By passing an electrical current through a thermoelectric material, one side is cooled while heat is transported to the opposite side. This solid‑state, vibration‑free, quiet, spot‑cooling capability makes thermoelectrics valuable for many semiconducting and electronic devices.

Abstract

Cooling electronic devices can often be necessary to optimize performance. Traditional approaches to cooling are typically based on thermodynamic cycles involving compression and expansion of refrigerant gases (such as Freon). The heat required for vaporization is drawn from the materials or the volume (for example, a refrigerator) that is to be cooled. Thermoelectric (TE) materials, in contrast, do not rely on chemicals or gases but rather on a special physical phenomena called the Peltier effect, which is explained in detail below (1). In TE materials, heat is not primarily transported by the lattice but by the electrical charge carriers—electrons or holes. Applying an electrical current through a TE material cools one end and transports the heat to the other end of the material or device. This has distinct advantages in that it is solid-state refrigeration, without moving parts and vibrations, and with quiet performance and the ability for localized “spot” cooling. This can be very important for many semiconducting and other electronic devices. But until recently, the efficiency of TE devices has been frustratingly low, and applications remain limited.