VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013

 QNplage

 Nanophysics: from fundamentals to applications

(the return)

 

Thursday 8
Topological Insulators

› 14:00 - 14:20 (20min)
Bulk doping of Bi2Te3 using electron irradiation
Willem Rischau  1, *@  , Kees Van Der Beek  1@  , Brigitte Leridon  2@  
1 : Laboratoire des Solides Irradiés  (LSI)  -  Website
Polytechnique - X
28 route de Saclay 91128 Palaiseau Cedex -  France
2 : Laboratoire de Physique et d'Étude des Matériaux  (LPEM)  -  Website
École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI)
10 Rue Vauquelin, Bat. C 75231 PARIS CEDEX 05 -  France
* : Corresponding author

Topological insulators such as Bi2Te3 are materials which are insulating in the bulk, but display conducting states at their surface. An ongoing challenge regarding electrical transport on these materials is the compensation of the bulk contribution to the conductance. Here we investigate a new possibility to lower the bulk conductivity of Bi2Te3 via doping using irradiation-induced defects. We have irradiated Bi2Te3 bulk single crystals at 300 K with 2.5 MeV electrons and investigated the irradiation-induced changes of the resistivity in-situ. We also measured the high-field magnetoresistance (14 T) ex-situ down to 1.9 K including Shubnikov-de Haas oscillations. It appears that it is possible to convert the conduction of Bi2Te3 from p-type to n-type using irradiation-induced defects, and to partially compensate the bulk carriers initially present in the crystal. Whereas the resistivity at 300 K of an optimally doped sample only increased by a factor two, we observe an increase by two orders of magnitude in the low-temperature resistivity. The low temperature carrier density decreased by an order of magnitude to 2-5E17 cm-3 for optimal compensation. The application of this irradiation-induced doping regarding the fabrication of bulk insulating topological insulators will be discussed.


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