Low-temperature ultrafast optical probing of topological bismuth selenide

Sharma, Prince; Sharma, Rahul; Awana, V. P. S.; Narayanan, Tharangattu N.; Vashistha, Nikita; Tyagi, Lavi; Kumar, Mahesh

doi:10.1016/j.jallcom.2021.161235

Cited by 15 publications

(37 citation statements)

References 52 publications

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“…The OATs near 1 and 2 eV are well predicted through ellipsometry studies in the literature 32 and supported by the previous studies. 16,28,32 Also, the OAT near 2 eV is predicted in all these films and is in accordance with the previously studied bulk flakes. 16,28,32 On comparing the dielectric constants, the peak value of the dielectric constant was found to be shifted from ∼1.8 to ∼2.8 and finally to ∼3.8 as QLs increased from 4 to 12.…”

Section: Resultssupporting

confidence: 91%

“…16,28,32 Also, the OAT near 2 eV is predicted in all these films and is in accordance with the previously studied bulk flakes. 16,28,32 On comparing the dielectric constants, the peak value of the dielectric constant was found to be shifted from ∼1.8 to ∼2.8 and finally to ∼3.8 as QLs increased from 4 to 12. It signifies the inclusion of bulk band states with increasing QLs.…”

Section: Resultssupporting

confidence: 91%

“…This peak corresponds to the 2 eV prominent optical band transitions that are observed in various other films and crystals of Bi 2 Se 3 in the literature. 28,32 It is important to highlight that the reflectance spectra of bulk single-crystal bismuth selenide are quite different in all these thin films. 28 The reflectance spectra are further used to determine the refractive index variation of these films by fitting the spectra with the Kramers−Kronig relation using RefFIT software.…”

Section: Resultsmentioning

confidence: 99%

“…28,32 It is important to highlight that the reflectance spectra of bulk single-crystal bismuth selenide are quite different in all these thin films. 28 The reflectance spectra are further used to determine the refractive index variation of these films by fitting the spectra with the Kramers−Kronig relation using RefFIT software. 27,38 The software depends on a modified Levenberg−Marquardt algorithm and helps to model the dielectric constants using the reflectance optical spectra.…”

Section: Resultsmentioning

confidence: 99%

“…However, there are OATs at 0.7, 1.0, 1.4, and 2.0 eV, which are also predicted through ellipsometry and TRUS. 28,32…”

Section: Resultsmentioning

confidence: 99%

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Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

et al. 2022

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In a broad probing spectral range covering visible to NIR, the transient reflectance study on bismuth selenide thin films, especially of 5–15 nm thickness, has not been carried out before. The independent carrier lifetimes in these films and the observation of resonant states in 10 nm thin films require an in-depth analysis of charge carriers and phonon modes to investigate the intrinsic states and to understand the probe-, pump-, and temperature-dependent effects. In this perspective, molecular beam epitaxy is used to grow 5-, 10-, and 15 nm-thin films of bismuth selenide, which are capped with a selenium layer of 1 nm on a c-cut sapphire substrate. After the structural and phonon-mode studies, reflectance spectroscopy is utilized to determine the refractive index of different thicknesses of films. Transient reflectance ultrafast spectroscopy is employed to probe the dynamics in the broad visible to NIR range, highlighting that the resonant feature is probe- and pump-dependent. Furthermore, temperature-dependent investigations in 10 nm films are performed to identify the intrinsic origin of the resonance effects down to 5 K. This article provides a comprehensive investigation of thin films of bismuth selenide to model the characteristic difference in the response of surface states with film thickness.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…However, there are OATs at 0.7, 1.0, 1.4, and 2.0 eV, which are also predicted through ellipsometry and TRUS. 28,32…”

Section: Resultsmentioning

confidence: 99%

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Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

et al. 2022

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Revealing Enhanced Optoelectronic Performance of Sb₂Se₃‐Based Self‐Sustaining Heterostructures with Bi₂Se₃ and ZnSe: A Dual Polarity Photo Response

Kumar,

Sharma,

Verma

et al. 2024

Adv Funct Materials

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Through precise band engineering, Van der Waals heterostructures integration holds great promise for advancing high‐performance optoelectronic devices, especially photodetectors. This study presents self‐sustaining, dual‐polarity, high photo‐responsive heterostrutures (HS) photodetectors based on Sb2Se3, specifically Bi2Se3/Sb2Se3 and ZnSe/Sb2Se3. The Bi2Se3 (ZnSe) layer functions as a channel in a reconfigurable HS phototransistor configuration. These HS devices demonstrate a negative photoconductive response with bias‐modulated polarity switching of the photocurrent. The Bi2Se3/Sb2Se3 device exhibits a responsivity switch from −4 mA W−1 to 0.14 A W−1, while the ZnSe/Sb2Se3 device shows a substantially enhanced responsivity switch from ‐400 mA W−1 to 12 A W−1. This negative photo response results from a photoinduced carrier trapping mechanism at the interface of the channel layer and photosensitizer material. The bias modulation enables the switching from negative to positive responsivity. A comprehensive investigation of photoconductivity modulation provides a deeper understanding of the impact of the photogating effect and trap states under applied bias conditions. Ultrafast transient spectroscopy supports these findings, offering insights into the dynamics of charge carrier relaxation mechanisms and the trapping of photoexcited carriers in defect states, crucial for explaining the dual polarity photo response. These devices present significant advantages for switchable light imaging, optical communication, memory devices, convolution processing, and logic circuits.

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Revealing the Substrate Dependent Ultrafast Phonon Dynamics in Bi₂Se₃ Thin Films

Saini

Tailor

Sharma

et al. 2022

Adv Materials Inter

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The bulk carrier excitation influences the phonon dynamics, which can alter and modulate the surface charge density of topological insulators such as bismuth selenide (Bi2Se3). This work investigates the charge carrier and phonon dynamics in Bi2Se3 grown on various substrates. The orientation of the substrate, the size of the crystallites, and the misfit of the lattice affect the carrier and phonon dynamics. Bi2Se3 thin films are grown under the same growth conditions on SiO2, Si(111), and SiN. Bi2Se3 overlayers exhibit substrate‐dependent charge carrier relaxation channels and phonon dynamics. It is evident from Raman spectroscopy and ultrafast transient absorption spectroscopy that the heterointerface interactions of all three samples affect the vibration modes of Bi2Se3 and coherent acoustic phonon oscillations in the NIR range. At 13.6, 41.2, and 34.4 GHz, the vibration modes of SiO2, Si(111), and SiN are equivalent. The propagation depth of phonon waves is shown by measuring the speed of sound in Bi2Se3 overlayers on SiO2, Si(111), and SiN. This study demonstrates that the surface and bulk‐bound charge carriers of a topological insulator determine the frequency and velocity of the generated sound.

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Low-temperature ultrafast optical probing of topological bismuth selenide

Cited by 15 publications

References 52 publications

Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

Revealing Enhanced Optoelectronic Performance of Sb₂Se₃‐Based Self‐Sustaining Heterostructures with Bi₂Se₃ and ZnSe: A Dual Polarity Photo Response

Revealing the Substrate Dependent Ultrafast Phonon Dynamics in Bi₂Se₃ Thin Films

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Low-temperature ultrafast optical probing of topological bismuth selenide

Cited by 15 publications

References 52 publications

Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

Comprehensive Study of the Topological Surface States through Ultrafast Pump–Probe Spectroscopy

Revealing Enhanced Optoelectronic Performance of Sb2Se3‐Based Self‐Sustaining Heterostructures with Bi2Se3 and ZnSe: A Dual Polarity Photo Response

Revealing the Substrate Dependent Ultrafast Phonon Dynamics in Bi2Se3 Thin Films

Contact Info

Product

Resources

About

Revealing Enhanced Optoelectronic Performance of Sb₂Se₃‐Based Self‐Sustaining Heterostructures with Bi₂Se₃ and ZnSe: A Dual Polarity Photo Response

Revealing the Substrate Dependent Ultrafast Phonon Dynamics in Bi₂Se₃ Thin Films