Restoring pristine Bi2Se3 surfaces with an effective Se decapping process

Dai, Jixia; Wang, Wenbo; Brahlek, Matthew; Koirala, Nikesh; Salehi, M.; Oh, Seongshik; Wu, Weida

doi:10.1007/s12274-014-0607-8

Cited by 37 publications

(34 citation statements)

References 33 publications

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“…[9]) we believe that other molecules from atmosphere, most likely water vapor, are the origin of the observed contamination. This conclusion emphasizes that for further ex situ electronic transport investigations and quantum device fabrication, films should first be capped in situ to avoid any possible contamination as has already been indicated for Bi 2 Se 3 thin films [54]. For Bi 2 Te 3 films, though, a systematic study is needed in order to determine a suitable capping layer that can preserve the surface states and avoid unintentional doping induced by ambient conditions.…”

Section: Extrinsic Defectsmentioning

confidence: 90%

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

et al. 2015

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In situ spectroscopy of intrinsic Bi2Te3 topological insulator thin films and impact of extrinsic defects Ngabonziza, P.; Heimbuch, R.; de Jong, N.; Klaassen, R.A.; Stehno, M.P.; Snelder, M.; Solmaz, A.; Ramankutty, S.V.; Frantzeskakis, E.; van Heumen, E.; Koster, G.; Golden, M.S.; Zandvliet, H.J.W.; Brinkman, A. Published in:Physical Review B DOI:10.1103/PhysRevB.92.035405 Link to publicationCitation for published version (APA): Ngabonziza, P., Heimbuch, R., de Jong, N., Klaassen, R. A., Stehno, M. P., Snelder, M., ... Brinkman, A. (2015). In situ spectroscopy of intrinsic Bi2Te3 topological insulator thin films and impact of extrinsic defects. Physical Review B, 92(3), [035405]. https://doi.org/10.1103/PhysRevB.92.035405 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Combined in situ x-ray photoemission spectroscopy, scanning tunneling spectroscopy, and angle resolved photoemission spectroscopy of molecular beam epitaxy grown Bi 2 Te 3 on lattice mismatched substrates reveal high quality stoichiometric thin films with topological surface states without a contribution from the bulk bands at the Fermi energy. The absence of bulk states at the Fermi energy is achieved without counterdoping. We observe that the surface morphology and electronic band structure of Bi 2 Te 3 are not affected by in vacuo storage and exposure to oxygen, whereas major changes are observed when exposed to ambient conditions. These films help define a pathway towards intrinsic topological devices.

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Section: Extrinsic Defectsmentioning

confidence: 90%

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

et al. 2015

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“…The samples were first sputtered with 500 eV argon ions for 15 minutes. Subsequently, they were annealed up to ~200 °C to desorb the amorphous Se, after which they were immediately transferred into the STM head for measurements 40 . …”

Section: Stm Measurementsmentioning

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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“…Se capping is preferably used due to its low desorption temperature, but it normally changes the surface stoichiometry of Te-based TI compounds during thermal decapping. 18,19 Refinements of this technique have shown that it is possible to restore pristine surfaces after thermal removal of sputtered Se capping on Bi 2 Se 3 , which was exposed to air for a few hours 20 or thermal desorption of ultra-thin Te capping on Bi 2 Te 3 films after exposition to air for 5 min. 21 A third technique applied to layered van der Waals materials consists of cleaving thin films (thicker than 50 nm) inside the UHV chamber to remove the oxidized surface, exposing a new fresh surface to perform the aimed analysis.…”

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confidence: 99%

Preservation of pristine Bi₂Te₃ thin film topological insulator surface after ex situ mechanical removal of Te capping layer

et al. 2016

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Restoring pristine Bi2Se3 surfaces with an effective Se decapping process

Cited by 37 publications

References 33 publications

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

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

Preservation of pristine Bi₂Te₃ thin film topological insulator surface after ex situ mechanical removal of Te capping layer

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Restoring pristine Bi2Se3 surfaces with an effective Se decapping process

Cited by 37 publications

References 33 publications

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

In situspectroscopy of intrinsicBi2Te3topological insulator thin films and impact of extrinsic defects

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

Preservation of pristine Bi2Te3 thin film topological insulator surface after ex situ mechanical removal of Te capping layer

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

Preservation of pristine Bi₂Te₃ thin film topological insulator surface after ex situ mechanical removal of Te capping layer