Eur. Phys. J. B (2014) 87: 64
https://doi.org/10.1140/epjb/e2014-50074-8

Regular Article

Thermoelectric energy conversion in layered structures with strained Ge quantum dots grown on Si surfaces

¹ Materials Science Institute, University of Valencia, P.O. Box 22085, 46071 Valencia, Spain
² Department of Physics, Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
³ Department of Electrical Engineering and the Center for Nano Science and Technology, National Central University, ChungLi 320, Taiwan

^a e-mail: olegk@univ.kiev.ua

Received: 31 January 2014
Published online: 12 March 2014

Abstract

The efficiency of the energy conversion devices depends in many ways on the materials used and various emerging cost-effective nanomaterials have promised huge potentials in highly efficient energy conversion. Here we show that thermoelectric voltage can be enhanced by a factor of 3 using layer-cake growth of Ge quantum dots through thermal oxidation of SiGe layers stacked in SiO₂/Si₃N₄ multilayer structure. The key to achieving this behavior has been to strain the Ge/Si interface by Ge dots migrating to Si substrate. Calculations taking into account the carrier trapping in the dot with a quantum transmission into the neighboring dot show satisfactory agreement with experiments above ≈200 K. The results may be of interest for improving the functionality of thermoelectric devices based on Ge/Si.