Enhanced figure of merit in thermal to electrical energy conversion using diode structures

A characterization of the electrical and thermal properties of thermoelectric diode structures indicates that the figure of merit for thermal to electrical energy conversion is significantly enhanced in our devices over thermoelectric values. Enhancements are due to current injection and blockage of the ohmic return current within the devices. The resulting device takes advantage of both thermoelectric and thermionic effects, and can be considered to be a hybrid. Experiments indicate an enhancement as high as a factor of 8 in the effective figure of merit. The best results are consistent with a conversion efficiency on the order of 35% of the Carnot limit. Enhancements have been observed in InSb and in HgCdTe, and we believe that the approach applies generally to all thermoelectric semiconductors. (C) 2002 American Institute of Physics.