@InProceedings{PirralhoPPSOFRA:2017:AnPhBi,
author = "Pirralho, Marilia Jesus P{\'a}scao and Peres, Marcelos Lima and
Pena, Fernando Silva and Soares, Demetrio A. W. and Okazaki,
Anderson K. and Fornari, Celso Israel and Rappl, Paulo Henrique de
Oliveira and Abramof, Eduardo",
affiliation = "{} and {} and {} and {} and {} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)}",
title = "Anomalous photoconductivity in Bi2Te3 topological insulator
films",
booktitle = "Resumos...",
year = "2017",
organization = "Brazilian Workshop on Semiconductor Physics, 18. (BWSP)",
abstract = "Topological insulators represent a new state of quantum matter
that have an insulating bulk band gap but present metallic surface
states. The surface states are topologically protected against
non-magnetic impurities and it is possible the existence of a pure
spin polarized current [1]. Three dimensional topological
insulator as Bi2Te3 has attracted attention due to its topological
properties and its potential application for development of
spintronic devices [2]. In literature there is little or no
information about photoconductivity in topological insulators, in
particular in Bi2Te3. Photoconductivity measurements represent a
powerful tool to probe the presence of defect states within be
band structure and transport via more than one conduction channel.
In this work we investigated the photoconductive properties of
Bi2Te3 epitaxial layers in the temperature range of 77 to 300K.
Unexpectedly, our measurements indicated that samples present
negative photoconductivity, where the conductivity reduces under
illumination, in the whole range of temperatures. In addition,
these measurements revealed the presence of persistent
photoconductivity effect for low temperatures, 77K-170K, which may
be associated to the existence of a defect level within the band
gap. From the photoconductivity decay curves, when light is
removed, we could extract recombination times as a function of
temperature and hence extract the energy associated to the traps
located in band gap[3]. This study will reveal the effect of
disorder in the photoconductivity properties in Bi2Te3 films and
the role of surface states in the negative photoconductivity
effect. Acknowledgments: The authors would like to acknowledge
CAPES and FAPEMIG for support. References: [1] P. Dziawa, et al,
Nature Materials 11, 1023 (2012); [2] Y. L. Chen, et al. Science
325, 178 (2009); [3] J.A.Hagmann, X.Liu, M.Dobrowolska and
J.K.Furdyna. Journal of Applied Physics, 113: 17C724., 2013.",
conference-location = "Maresias, SP",
conference-year = "14-18 ago.",
language = "en",
targetfile = "abramof_anomalous.pdf",
urlaccessdate = "27 abr. 2024"
}