Optoelectronic properties of Ta$_3$N$_5$: A joint theoretical and experimental study

ORAL

Abstract

A joint theoretical and experimental study of the optoelectronic properties of Ta$_3$N$_5$ was conducted by means of ab initio calculations and ellipsometry measurements [1]. Previous experimental work on Ta$_3$N$_5$ has not been conclusive regarding the direct or indirect nature of light absorption. Our work found excellent agreement between the optical spectrum computed using the Bethe-Salpeter equation and the measured one, with two prominent features occurring at 2.1 and 2.5 eV assigned to direct transitions between N and Ta states. The computed optical gap, obtained from the $G_0W_0$ direct photoemission gap, including spin-orbit coupling, electron-phonon interaction, and exciton binding energy, was found to be in excellent agreement with measurements. Our results also showed that Ta$_3$N$_5$ is a highly anisotropic material with heavy holes in several directions, suggesting low hole mobilities, consistent with low measured photocurrents in the Ta$_3$N$_5$ literature. Work is in progress to compute polaronic contributions to the hole and electron mobilities and to investigate the effect of substitutional doping on the electronic structure of Ta$_3$N$_5$.\\[4pt] [1] Juliana M. Morbec, Ieva Narkeviciute, Thomas F. Jaramillo, and Giulia Galli, Phys. Rev. B 90, 155204 (2014).

–

Authors

  • Juliana Morbec

    Institute for Molecular Engineering, University of Chicago, USA

  • Ieva Narkeviciute

    Department of Chemical Engineering, Stanford University, USA

  • Thomas Jaramillo

    Department of Chemical Engineering, Stanford University, USA

  • Giulia Galli

    The University of Chicago, Institute for Molecular Engineering, the University of Chicago, University of Chicago, Institute for Molecular Engineering, Institute for Molecular Engineering, University of Chicago, Univ of Chicago, Institute for Molecular Engineering, The University of Chicago; Materials Science Division, Argonne National Laboratory, University of Chicago, Institute for Molecular Engineering, University of Chicago, USA, The Institute for Molecular Engineering, The University of Chicago