Stability of low-carrier-density topological-insulator Bi<sub>2</sub>Se<sub>3</sub> thin films and effect of capping layers

Salehi, M.; Brahlek, Matthew; Koirala, Nikesh; Moon, Jisoo; Wu, Liang; Armitage, N. P.; Oh, Seongshik

doi:10.1063/1.4931767

Cited by 26 publications

(29 citation statements)

References 21 publications

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“…Films grow a quintuple layer (1 unit cell) at a time (1 QL ∼1 nm). 50 nm MoO 3 was deposited in-situ and was followed by 100 nm amorphous Se to reduce aging effects (42). Details on the growth can be found elsewhere (18).…”

Section: Experimental Methodsmentioning

confidence: 99%

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Salehi

Koirala

et al. 2016

Science

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327

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Section: Experimental Methodsmentioning

confidence: 99%

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Salehi

Koirala

et al. 2016

Science

Self Cite

327

252

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“…In order to check the effect of the air exposure, we subsequently grew another set of samples with Se capping layer, which was previously shown to be effective in protecting the surface of Bi2Se3 films from air exposure 28 . As depicted in Figure 1b, the Se capping does make a difference and 50 QL Bi2Se3 film on Al2O3 is now converted to p-type.…”

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confidence: 99%

Solution to the Hole-Doping Problem and Tunable Quantum Hall Effect in Bi₂Se₃ Thin Films

et al. 2018

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ABSTRACT. Bi2Se3, one of the most widely studied topological insulators (TIs), is naturally electron-doped due to n-type native defects. However, many years of efforts to achieve p-type Bi2Se3 thin films have failed so far. Here, we provide a solution to this long-standing problem, showing that the main culprit has been the high density of interfacial defects. By suppressing these defects through an interfacial engineering scheme, we have successfully implemented p-type Bi2Se3 thin films down to the thinnest topological regime. On this platform, we present the first tunable quantum Hall effect (QHE) study in Bi2Se3 thin films, and reveal not only significantly asymmetric QHE signatures across the Dirac point but also the presence of competing anomalous states near the zeroth Landau level. The availability of doping tunable Bi2Se3 thin films will now make it possible to implement various topological quantum devices, previously inaccessible.KEYWORDS. Topological insulator, Bi2Se3, Doping, Interface, Quantum Hall effect 3 Hole (p) doping has been challenging in Bi2Se3 1-3 , one of the most widely studied topological insulators (TIs) [4][5][6][7][8][9][10] . Unlike conventional semiconductor materials, the problem is complicated due to the presence of both surface and bulk states in topological insulators: we have to consider the doping problem of the surface and the bulk states separately. Both the surface and bulk states of Bi2Se3 have a strong tendency toward n-type due to its native n-type defects such as selenium vacancies [1][2][3][11][12][13][14][15][16][17] . In bulk crystals compensation dopants such as Ca and Mn can be used to convert the dominant carrier type from n-to p-type [18][19][20][21][22][23][24][25] . However, such a compensation doping scheme has not been successful in thin films of Bi2Se3. More specifically, we have tried various potential p-type dopants such as Zn, Mg, Ca, Sr, and Ba as compensation dopants, but none of them have so far led to p-type Bi2Se3 thin films; no p-type Bi2Se3 thin films have been demonstrated in the literature either. Only when they were quite thick (~200 nm), we were able to achieve p-type Bi2Se3 films through a complex process 8 . This difficulty in achieving p-type Bi2Se3 thin films has been puzzling, considering the very existence of p-type Bi2Se3 bulk crystals 19,20 . It may be suspected that this discrepancy in doping efficiency between thin films and bulk crystals could be due to the different growth conditions of the two systems, such as growth temperatures, considering that films are, in general, grown at much lower temperatures than bulk crystals. However, it should be noted that even p-type Bi2Se3 bulk crystals tend to become n-type when the crystals are made into thin flakes through, say, the Scotch tape method 26 . Bi2Se3 flakes can remain p-type only if they are relatively thick (> ~150 nm) 24 . All these observations provide evidence that whether they are thin films or bulk crystals, thickness critically affects the doping efficiency of the Bi2Se3 syst...

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“…Such systems include the 2D surface of a general 3D topological insulator. [25][26][27][28][29][30][31][32][33][34] In such cases, the low-energy electronic states possess linear dispersions and behave as massless Dirac fermions. When time reversal symmetry is broken by, e.g., a local magnetisation 28,35 or a magnetic field [35][36][37][38] then gaps open in the surface band structure.…”

Section: Introductionmentioning

confidence: 99%

Edge modes and Fabry-Perot plasmonic resonances in anomalous-Hall thin films

2019

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We study plasmon propagation on a metallic two-dimensional surface partially coated with a thin film of anomalous-Hall material. The resulting three regions, separated by two sharp interfaces, are characterised by different Hall conductivities but identical normal conductivities. A single bound mode is found, which can localise to either interface and has an asymmetric potential profile across the region. For propagating modes, we calculate the reflection and transmission coefficients through the magnetic region. We find Airy transmission patterns with sharp maxima and minima as a function of the plasmon incidence angle. The system therefore behaves as a high-quality filter.

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Stability of low-carrier-density topological-insulator Bi₂Se₃ thin films and effect of capping layers

Cited by 26 publications

References 21 publications

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Solution to the Hole-Doping Problem and Tunable Quantum Hall Effect in Bi₂Se₃ Thin Films

Edge modes and Fabry-Perot plasmonic resonances in anomalous-Hall thin films

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Stability of low-carrier-density topological-insulator Bi2Se3 thin films and effect of capping layers

Cited by 26 publications

References 21 publications

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Solution to the Hole-Doping Problem and Tunable Quantum Hall Effect in Bi2Se3 Thin Films

Edge modes and Fabry-Perot plasmonic resonances in anomalous-Hall thin films

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Stability of low-carrier-density topological-insulator Bi₂Se₃ thin films and effect of capping layers

Solution to the Hole-Doping Problem and Tunable Quantum Hall Effect in Bi₂Se₃ Thin Films