Thermoelectric figure of merit as a function of carrier propagation angle in semiconducting superlattices

Superlattices have been a fruitful approach for enhancing the figure of merit, ZT, of thermoelectric materials. Generally, superlattice transport is measured either parallel or perpendicular to the superlattice planes. We show here that the figure of merit is a function of carrier propagation angle in the superlattice and that ZT generically exhibits a maximum at an oblique angle, near θ ≈ π/6.