Minority carrier barrier heterojunctions for improved thermoelectric efficiency

0.1016/j.nanoen.2 lsevier Ltd. All rig thor. [email protected] Abstract We propose and demonstrate the beneficial use of minority carrier blocking layers to lessen bipolar conduction at elevated temperatures and increase the Seebeck coefficient in a thermoelectric material. Bipolar conduction, caused by thermally activated intrinsic carriers in semiconductors, causes a detrimental “roll-over” in the Seebeck coefficient and increase in thermal conductivity, measured as a function of temperature. We propose that these negative effects can be lessened or delayed in a small band gap host matrix by incorporating wider band gap semiconductor layers to impede the thermal diffusion of minority carriers over majority carriers. To prove this concept, a composite material grown by molecular beam epitaxy of ptype InAs layers and electron blocking p-type AlSb layers were grown and measured. We show improved thermoelectric properties over just p-type InAs in measurements from 110 K to 600 K. & 2015 Elsevier Ltd. All rights reserved.