Cross-plane Seebeck coefficient in superlattice structures in the miniband conduction regime

We have studied experimentally and theoretically the cross-plane Seebeck coefficient of short period InGaAs/InAlAs superlattices with doping concentrations ranging from 2x10(18) up to 3x10(19) cm(-3). Measurements are performed with integrated thin film heaters in a wide temperature range of 10-300 K. It was interesting to find out that contrary to the behavior in bulk material the Seebeck coefficient did not decrease monotonically with the doping concentration. We did not observe a sign change in the Seebeck coefficient at dopings where the Fermi energy is just above a miniband. This is a sign that electrons’ lateral momentum is conserved in the transport perpendicular to superlattice layers. A preliminary theory of thermoelectric transport in superlattices in the regime of miniband formation has been developed to fit the experimental results. Cross-plane Seebeck coefficient in superlattice structures in the miniband conduction regime Daryoosh Vashaee,1,* Yan Zhang,1 Ali Shakouri,1 Gehong Zeng,2 and Yi-Jen Chiu2 1Jack Baskin School of Engineering, University of California, Santa Cruz, California 95064, USA 2Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106, USA Received 11 July 2006; revised manuscript received 18 September 2006; published 9 November 2006 We have studied experimentally and theoretically the cross-plane Seebeck coefficient of short period InGaAs/ InAlAs superlattices with doping concentrations ranging from 2 1018 up to 3 1019 cm−3. Measurements are performed with integrated thin film heaters in a wide temperature range of 10–300 K. It was interesting to find out that contrary to the behavior in bulk material the Seebeck coefficient did not decrease monotonically with the doping concentration. We did not observe a sign change in the Seebeck coefficient at dopings where the Fermi energy is just above a miniband. This is a sign that electrons’ lateral momentum is conserved in the transport perpendicular to superlattice layers. A preliminary theory of thermoelectric transport in superlattices in the regime of miniband formation has been developed to fit the experimental results. DOI: 10.1103/PhysRevB.74.195315 PACS number s : 73.50.Lw, 73.63. b