First-principles study of native point defects in Bi2Se3

Xue, Lin; Zhou, Pan; Zhang, C. X.; Hé, Changyong; Hao, Guolin; Sun, L. Z.; Zhong, Jianxin

doi:10.1063/1.4804439

Cited by 80 publications

(58 citation statements)

References 47 publications

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“…41 Vacancies, on the other hand, were found to play no role. In Bi 2 Se 3 , on the other hand, Se vacancies are dominant and lead to n-type doping, 42 which is a great disadvantage for thermoelectric applications for which both types of conduction are required. 23 Mn doping has been reported to allow for controlled charge doping with a crossover from n-to p-type above 5% Mn.…”

Section: Discussionmentioning

confidence: 99%

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

et al. 2014

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We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE), investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), SQUID magnetometry and x-ray magnetic circular dichroism (XMCD). Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS), and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.

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Section: Discussionmentioning

confidence: 99%

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

et al. 2014

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“…[9][10][11][12] Recent reports show that mechanical exfoliation of a single QL and of slabs of a few QLs of Bi 2 Se 3 is possible and that excellent TE properties can be expected in such thin films. [13][14][15][16][17] Sun and coworkers 14 have shown that the TE behavior of a single QL of Bi 2 Se 3 is enhanced because of a reduced j, as compared to the bulk value.…”

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confidence: 99%

Thickness and strain effects on the thermoelectric transport in nanostructured Bi₂Se₃

2014

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“…The remainder of the film is grown in a second step at a temperature of 275 o C to produce a smoother film. Figure 1 It is suspected that selenium vacancies 17,18 quickly alter the surface potential and subsequently lead to oxidation when exposed to air. Consequently, a 10-nm thick MgF 2 capping layer is sputtered onto the samples without removing them from the growth chamber.…”

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Coherent control of injection currents in high-quality films of Bi2Se3

Bas

Vargas-Velez

Babakiray

et al. 2015

Applied Physics Letters

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Films of the topological insulator Bi 2 Se 3 are grown by molecular beam epitaxy with in-situ reflection high-energy electron diffraction. The films are shown to be high-quality by X-ray reflectivity and diffraction and atomic-force microscopy. Quantum interference control of photocurrents is observed by excitation with harmonically related pulses and detected by terahertz radiation. The injection current obeys the expected excitation irradiance dependence, showing linear dependence on the fundamental pulse irradiance and square-root irradiance dependence of the frequency-doubled optical pulses. The injection current also follows a sinusoidal relative-phase dependence between the two excitation pulses.These results confirm the third-order nonlinear optical origins of the coherently controlled injection current. Experiments are compared to a tight-binding band structure to illustrate the possible optical transitions that occur in creating the injection current.2 Bi 2 Se 3 is a well-known thermoelectric material 1 and currently of great interest in condensed matter physics because the surface states exhibit massless Dirac dispersions in the gaps between the bulk valence and conduction bands. 2 The surface states have an electron spin structure defined by strong spin-orbit coupling which locks the spin vector perpendicular to the momentum vector. 3,4 Fundamental properties of Bi 2 Se 3 have been widely investigated because of the potential opportunities for developing spintronic and optically controlled devices.A great deal of attention has been paid to the light-matter interactions because the surface states of Bi 2 Se 3 are obscured in electrical measurements, due to inherent n-doping in the as-grown material. This means that the Fermi level is in the bulk conduction band above the 0.3-eV band gap. Despite this fact, optical measurements have been widely explored in the near infrared, revealing anomalous absorption coefficients with film thickness, 5 strong coupling between electrons and phonons 6,7 and a second set of massless surface states at about 1.7 eV above the commonly studied Dirac point below the Fermi level. 8 These developments, among others, 9 indicate that near-infrared optical interactions provide mechanisms that can be exploited for photonic devices and also access surface-surface state excitations. In which case, coupling of optical radiation to inject and control photocurrents is then relevant for the performance of this material system and coupling to the all-important surface states.Photocurrents in Bi 2 Se 3 have been predicted 10 and measured 11 using circular polarization, through the circular photogalvanic effect. Experimental studies have been performed in exfoliated Bi 2 Se 3 patterned with contacts that are sensitive to both photocurrents and photo-thermal currents. Nonetheless, this study has demonstrated that photocurrents can indeed be controlled. A more discrete scheme has been proposed for coherent control of the surface states using two-color quantum interference. 12 Quant...

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First-principles study of native point defects in Bi2Se3

Abstract: The quantum spin Hall effect and topological insulators Physics Today 63, 33 (2010); https://doi

Cited by 80 publications

References 47 publications

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

Thickness and strain effects on the thermoelectric transport in nanostructured Bi₂Se₃

Coherent control of injection currents in high-quality films of Bi2Se3

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First-principles study of native point defects in Bi2Se3

Abstract: The quantum spin Hall effect and topological insulators Physics Today 63, 33 (2010); https://doi

Cited by 80 publications

References 47 publications

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

Thickness and strain effects on the thermoelectric transport in nanostructured Bi2Se3

Coherent control of injection currents in high-quality films of Bi2Se3

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Thickness and strain effects on the thermoelectric transport in nanostructured Bi₂Se₃