Квантовый размерный эффект и осцилляции Шубникова–де Гааза в поперечном магнитном поле в полупроводниковых нитях Bi0,92Sb0,08

The transport properties, magnetoresistance, and Shubnikov–de Haas (SdH) oscillations of glass-coated Bi0.92Sb0.08 single-crystal wires with diameters of 180 nm to 2.2 mm and the (1011) orientation along the wire axis, which are prepared by liquid phase casting, have been studied. For the first time, it has been found that the energy gap DE increases by a factor of 4 with a decrease in the wire diameter d owing to the manifestation of the quantum size effect. This significant increase in the energy gap can occur under conditions of an energy–momentum linear dispersion relation, which is characteristic of both the gapless state and the surface states of a topological insulator. It has been shown that, in a strong magnetic field at low temperatures, a semiconductor–semimetal transition occurs; it is evident in the temperature dependences of resistance in a magnetic field. An analysis of the SdH oscillations, namely, the phase shift of the Landau levels and the features of the angular dependences of the oscillation periods, suggests that the combination of the manifestation of the topological insulator properties and the quantum size effect leads to the occurrence of new effects in low-dimensional structures, which requires new scientific approaches and applications in microelectronics

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Transport Properties of Topological Insulator Bi0.83Sb0.17 Nanowires

MRS Proceedings ◽

10.1557/opl.2015.375 ◽

2015 ◽

Vol 1785 ◽

pp. 1-6

Author(s):

L.A. Konopko ◽

A.A. Nikolaeva ◽

T.E. Huber ◽

J.P. Ansermet

Keyword(s):

Magnetic Field ◽

Single Crystal ◽

Transport Properties ◽

Topological Insulator ◽

Energy Gap ◽

Oscillation Amplitude ◽

Glass Capillary ◽

Wire Axis ◽

Temperature Dependences ◽

The Wire

ABSTRACTWe have investigated the transport properties of topological insulator based on single-crystal Bi0.83Sb0.17 nanowires. The single-crystal nanowire samples in the diameter range 200 nm – 1.1 μm were prepared by the high frequency liquid phase casting in a glass capillary using an improved Ulitovsky technique; they were cylindrical single-crystals with (1011) orientation along the wire axis. In this orientation, the wire axis makes an angle of 19.5o with the bisector axis C1 in the bisector-trigonal plane. Bi0.83Sb0.17 is a narrow gap semiconductor with energy gap at L point of Brillouin zone ΔE= 21 meV. In accordance with the measurements of the temperature dependence of the resistivity of the samples resistance increases with decreasing temperature, but at low temperatures decrease in the resistance is observed. This effect, decrease in the resistance, is a clear manifestation of the interesting properties of topological insulators - the presence on its surface of a highly conducting zone. The Arrhenius plot of resistance R in samples with diameter d=1.1 µm and d=200 nm indicates a thermal activation behavior with an activation gap ΔE= 21 and 35 meV, respectively, which proves the presence of the quantum size effect in these samples. We found that in the range of diameter 1100 nm - 200 nm when the diameter decreases the energy gap is growing as 1/d. We have investigated magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. From the temperature dependences of Shubnikov de Haas oscillation amplitude for different orientation of magnetic field we have calculated the cyclotron mass mc and Dingle temperature TD for longitudinal and transverse (B||C3 and B||C2) directions of magnetic fields, which equal 1.96*10-2m0, 9.8 K, 8.5*10-3m0 , 9.4 K and 1.5*10-1m0 , 2.8 K respectively. The observed effects are discussed.

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