APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session E2: Computational Methods for Improved Transparent Conducting Oxides
8:00 AM–11:00 AM,
Tuesday, March 15, 2016
Room: Ballroom II
Sponsoring
Units:
DCOMP DCMP
Chair: Giulia Galli, Univ of Chicago
Abstract ID: BAPS.2016.MAR.E2.5
Abstract: E2.00005 : Hybrid functional studies of defects and hole polarons in oxides.
10:24 AM–11:00 AM
Preview Abstract
Abstract
Author:
Joel Varley
(Lawrence Livermore Natl Lab)
Transparent conducting oxides (TCOs) are ubiquitous, appearing in windows,
flat-panel displays, solar cells, solid-state lighting, and transistors that
all exploit TCOs' combination of high electrical conductivity and optical
transparency. Thanks to this large and growing list of applications, there
has been a surge of interest in the science of these materials, focusing on
the fundamental properties and doping opportunities in traditional TCOs as
well as the exploration of promising new candidate materials. Hybrid density
functional theory has proven instrumental in elucidating the physics of
TCOs. One example is the study of dopants and defects that determine the
conductivity. Accurate formation energies and charge-state transition levels
can now be obtained thanks to the accurate electronic structure provided by
a hybrid functional. This allows us to address the origins of unintentional
conductivity: for SnO$_{\mathrm{2}}$, In$_{\mathrm{2}}$O$_{\mathrm{3}}$, and
Ga$_{\mathrm{2}}$O$_{\mathrm{3}}$, we demonstrate that this is \textit{not} due to
native defects such as oxygen vacancies, but must be attributed to
unintentional incorporation of impurities. We can also provide guidelines
for achieving higher doping levels, suggesting several impurities as
candidate donors with high solubility. Limitations on doping due to the
formation or incorporation of compensating centers are addressed as well.
Hybrid functional calculations also overcome the shortcomings associated
with traditional local or semi-local functionals, which do not properly
describe charge localization. Hybrid functionals accurately describe polaron
formation, i.e., the self-trapping of holes when $p-$type doping of the oxide
materials is attempted. Consequences of polaron formation for optical
characterization of the material will be discussed.
This work was performed in collaboration with Anderson Janotti and Chris G.
Van de Walle, and was in part under the auspices of the U.S. Department of
Energy by Lawrence Livermore National Laboratory under Contract
DE-AC52-07NA27344.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.E2.5