[institut] Podsetnik, Seminar, sutra (cetvrtak) u 12.00, Institut za fiziku - Jacim Jacimovic

[Milos Radonjic]

Поштоване колегинице и колеге,

Позивам вас да у четвртак, 25. јула 2013. године дођете на семинар који
ће са почетком у 12.00 у читаоници Института за физику одржати др Јаћим
Јаћимовић (Laboratory of Physics of Complex Matter, EPFL, Switzerland).
Назив семинара је:

Nature of charge carriers and mechanism of conductivity in anatase
TiO2

Abstract:

Titanium dioxide (TiO2) a wide band gap semiconductor emerged as one of
the most promising functional materials. In nature it occurs in there
different forms: rutile, brookite and anatase. The anatase phase
attracts the largest attention since it is essential for fabrication of
dye sensitized solar cells, memristors and of photocatalitic devices.
Recently, anatase has been discovered to be an ideal host for magnetic
ions, arising as a candidate to marry semiconductor technology and the
advantages of spintronics information development. Oxygen vacancies are
known to be the native defects in the crystal structure giving rise to
the existence of the shallow donor level. We present here results of a
detailed study of oxygen deficient single crystal samples obtained by
means of transport coefficient, THz optical conductivity, ARPES and STM
measurements. Strong evidences for the existence of large polarons with
diameter much smaller than typical size of anatase nanoparticles and
nanowires are found. We show that mass of the polarons and their
mobility depends of the polaron concentration. It was observed that
electron phonon interaction rules the conductivity in anatase phase.
Ultimately, we discovered that polaronic nature of the charge carriers
results in one more distinctive feature of this compound, it is huge
Seebeck coefficient which puts this material as a potential
thermoelectric.

[1] J. Jaćimović, C. Vâju, R. Gaál, A. Magrez, H. Berger, L. Forró , V.
Cerovski and R. Zikić “Pressuredependence of the large polaron transport
in anatase TiO2 singlecrystals” European Physics Letter, 99,
(2012),57005.

[2] J. Jaćimović, R. Gaál, A. Magrez, L. Forró, M. Regmi, G. Eres,
Electrical property measurements ofCr-N codoped TiO2 epitaxial thin
films grown by pulsed laserdeposition, Appl. Phys. Lett. 102, 172108
(2013).

[3] J. Jaćimović, R. Gaál, A. Magrez, J. Piatek, L. Forró, S. Nakao, Y.
Hirose, and T. Hasegawa, Lowtemperature resistivity, thermoelectricity,
and power factor of Nb dopedanatase TiO2, Appl. Phys. Lett. 102, 013901
(2013)

[4] S. Moser*, L. Moreschini*, J. Jaćimović *, O. S. Barısic, H. Berger,
A. Magrez, A. Bostwick, E. Rotenberg, L. Forro and M. Grioni, Tunable
polaronic conduction inanatase TiO2, Phys. Rev. Lett. 110, 196403 (2013)


Срдачан поздрав,
Милош Радоњић

-- 
Milos Radonjic
Research Assistant
E-mail: milos.radonjic at ipb.ac.rs
Web: http://www.scl.rs/

Phone: +381 11 3713152
Fax: +381 11 3162190

Scientific Computing Laboratory,
Institute of Physics Belgrade,
Pregrevica 118, 11080 Belgrade, Serbia