Enhanced solid-state thermionic emission in nonplanar heterostructures

Conservation of transverse momentum during thermionic emission from planar structures is a key factor limiting the number of hot electrons emitted and the efficiency of solid-state thermionic energy conversion devices. In this letter, electron emission from nonplanar potential barrier structures is analyzed using a Monte Carlo transport model. Compared to the planar structures, nonplanar tall barriers can achieve much larger emission currents. Although the average energy of the transmitted electrons drops a little, the thermoelectric figure of merit can be increased with a nonplanar barrier structure. The improvement of the thermoelectric properties is attributed to the combined effects of increased effective interface area and reduced probability of total internal reflection at heterostructure interfaces.(c) 2006 American Institute of Physics.