Driving Perpendicular Heat Flow: Ambipolar Transverse Thermoelectrics for Microscale and Cryogenic Peltier Cooling

Whereas thermoelectric performance is normally limited by the figure of merit ZT, transverse thermoelectrics can achieve arbitrarily large temperature differences in a single leg even with inferior ZT by being geometrically tapered. We introduce a band-engineered transverse thermoelectric with p-type Seebeck in one direction and n-type orthogonal, resulting in off-diagonal terms that drive heat flow transverse to electrical current. Such materials are advantageous for microscale devices and cryogenic temperatures -- exactly the regimes where standard longitudinal thermoelectrics fail. InAs/GaSb type II superlattices are shown to have the appropriate band structure for use as a transverse thermoelectric.