Eric Toberer

Colorado School of Mines, USA

Controlling Thermal Conductivity through Native Defects, Extrinsic Dopants, and Alloying in Thermoelectric Materials

Abstract:  Our ability to predict and experimentally control defect populations in complex semiconductors has dramatically improved over the last decade. In particular, phase boundary mapping of ternary and quaternary semiconductors allows for a diverse array of defect physics to be explored.  In this talk, we will explore how the control of defect populations can be experimentally realized and investigate the impact of such defect populations on elastic and thermal properties.  Through phonon calculations, we rationalize the impact of such defects and move towards generalized defect design rules for thermal conductivity. Beyond simple mass scattering, we focus on the nanoscale strain fields surrounding point defects. These efforts are then extended to isoelectronic alloys, where the disorder is at significantly higher concentrations. Throughout these efforts, synchrotron-based techniques (e.g., resonant X-ray diffraction) are used to connect the experimental properties with the predicted local structure.  Such efforts build the foundational knowledge required to identify defects and alloys that strongly scatter phonons while remaining comparatively benign to electron transport

Bio

Eric Toberer is an Associate Professor of Physics at the Colorado School of Mines and a Staff Scientist at the National Renewable Energy Laboratory.  His research is focused on the design of novel semiconductors, with a particular focus on thermoelectrics, photovoltaics, and light emitting diodes.  These efforts occur at the nexus of experimental solid state chemistry, first principles calculations, and advanced beamline characterization techniques.  Prior to moving to Colorado, he was a postdoc at Caltech and a graduate student in Materials Science at the University of California, Santa Barbara.