Multilayer thermionic transport in semiconductor superlattices

Using the kinetic equation including multilayer hopping processes, we have investigated theoretically the thermoelectric transport in a semiconductor superlattice, taking into account the effect of charge buildup. Our unified approach, which treats multilayer systems and homogeneous bulk systems on equal footing, demonstrates the important role of carrier mean free path, which in most existing works on thermionic emission based on the Richardson current is assumed to be equal to the barrier width. Our numerical results indicate a substantial increase in the figure of merit due to the multilayer hopping, which does not affect the thermopower significantly as expected.