Thermoelectric figure of merit of metal-semiconductor barrier structure based on energy relaxation length

The thermoelectric figure of merit is calculated for a compound material comprising thin semiconductor and wider metallic layers. The layers are perpendicular to the direction of current. The semiconductor barriers exclude electrons with energies epsilon < mu from the current. This exclusion increases thermopower. One may obtain a material with a very high ZT if the distance between the barriers is on the order of the energy relaxation length. This material should have the resistivity characteristic of a metal and the thermopower characteristic of a semiconductor. An additional significant rise in ZT can be achieved by increasing the contact area at the metal-semiconductor interface. (C) 1998 American Institute of Physics. [S0003-6951(98)04339-3].