Dynamics of exciton recombination in strong magnetic fields in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment

First-principle calculations based on the density functional theory (DFT) are implemented to study the structural and electronic properties of the SiS2/WSe2 hetero-bilayers. It is found that the AB-2 stacking model is most stable among all the six SiS2/WSe2 heterostructures considered in this work. The AB-2 stacking SiS2/WSe2 hetero-bilayer possesses a type-II band alignment with a narrow indirect band gap (0.154 eV and 0.738 eV obtained by GGA-PBE and HSE06, respectively), which can effectively separate the photogenerated electron–hole pairs and prevent the recombination of the electron–hole pairs. Our results revealed that the band gap can be tuned effectively within the range of elastic deformation (biaxial strain range from −7% to 7%) while maintaining the type-II band alignment. Furthermore, due to the effective regulation of interlayer charge transfer, the band gap along with the band offset of the SiS2/WSe2 heterostructure can also be modulated effectively by applying a vertical external electric field. Our results offer interesting alternatives for the engineering of two-dimensional material-based optoelectronic nanodevices.

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Recombination and spin dynamics of excitons in thin (Ga,Al)(Sb,As)/AlAs quantum wells with an indirect band gap and type-I band alignment

Physical Review B ◽

10.1103/physrevb.102.165423 ◽

2020 ◽

Vol 102 (16) ◽

Author(s):

T. S. Shamirzaev ◽

D. R. Yakovlev ◽

A. K. Bakarov ◽

N. E. Kopteva ◽

D. Kudlacik ◽

...

Keyword(s):

Quantum Wells ◽

Band Gap ◽

Spin Dynamics ◽

Band Alignment ◽

Type I ◽

Indirect Band Gap

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Exciton recombination dynamics in an ensemble of (In,Al)As/AlAs quantum dots with indirect band-gap and type-I band alignment

Physical Review B ◽

10.1103/physrevb.84.155318 ◽

2011 ◽

Vol 84 (15) ◽

Cited By ~ 33

Author(s):

T. S. Shamirzaev ◽

J. Debus ◽

D. S. Abramkin ◽

D. Dunker ◽

D. R. Yakovlev ◽

...

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Band Alignment ◽

Type I ◽

Exciton Recombination ◽

Indirect Band Gap ◽

Recombination Dynamics

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Ultrafast Charge Separation in Bilayer WS2/Graphene Heterostructure Revealed by Time- and Angle-Resolved Photoemission Spectroscopy

Frontiers in Physics ◽

10.3389/fphy.2021.668149 ◽

2021 ◽

Vol 9 ◽

Author(s):

Razvan Krause ◽

Mariana Chávez-Cervantes ◽

Sven Aeschlimann ◽

Stiven Forti ◽

Filippo Fabbri ◽

...

Keyword(s):

Charge Separation ◽

Graphene Layer ◽

Optoelectronic Devices ◽

Visible Spectral Range ◽

Band Alignment ◽

Photoemission Spectroscopy ◽

Type I ◽

Type Ii ◽

Angle Resolved Photoemission Spectroscopy ◽

Indirect Band Gap

Efficient light harvesting devices need to combine strong absorption in the visible spectral range with efficient ultrafast charge separation. These features commonly occur in novel ultimately thin van der Waals heterostructures with type II band alignment. Recently, ultrafast charge separation was also observed in monolayer WS2/graphene heterostructures with type I band alignment. Here we use time- and angle-resolved photoemission spectroscopy to show that ultrafast charge separation also occurs at the interface between bilayer WS2 and graphene indicating that the indirect band gap of bilayer WS2 does not affect the charge transfer to the graphene layer. The microscopic insights gained in the present study will turn out to be useful for the design of novel optoelectronic devices.

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Type II Band Alignment inSi1−xGex/Si(001)Quantum Wells: The Ubiquitous Type I Luminescence Results from Band Bending

Physical Review Letters ◽

10.1103/physrevlett.79.269 ◽

1997 ◽

Vol 79 (2) ◽

pp. 269-272 ◽

Cited By ~ 107

Author(s):

M. L. W. Thewalt ◽

D. A. Harrison ◽

C. F. Reinhart ◽

J. A. Wolk ◽

H. Lafontaine

Keyword(s):

Quantum Wells ◽

Band Alignment ◽

Type I ◽

Type Ii ◽

Band Bending

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Anisotropic exciton and charged exciton dichroic photoluminescence in undoped ZnSe/BeTe type-II quantum wells in magnetic fields

Physica E Low-dimensional Systems and Nanostructures ◽

10.1016/j.physe.2009.12.004 ◽

2010 ◽

Vol 42 (4) ◽

pp. 1172-1175

Author(s):

R. Shen ◽

E. Kojima ◽

R. Akimoto ◽

S. Takeyama

Keyword(s):

Magnetic Fields ◽

Quantum Wells ◽

Type Ii ◽

Charged Exciton ◽

Type Ii Quantum Wells

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TEMPERATURE DEPENDENCE OF PHOTOLUMINESCENCE OF FLAT AND UNDULATED SiGe/Si MULTIPLE QUANTUM WELLS

International Journal of Modern Physics B ◽

10.1142/s0217979202015108 ◽

2002 ◽

Vol 16 (28n29) ◽

pp. 4211-4214 ◽

Cited By ~ 3

Author(s):

B. W. CHENG ◽

J. G. ZHANG ◽

Y. H. ZUO ◽

R. W. MAO ◽

C. J. HUANG ◽

...

Keyword(s):

Elevated Temperature ◽

Quantum Wells ◽

Blue Shift ◽

Band Alignment ◽

Multiple Quantum Wells ◽

Luminescence Spectra ◽

Multiple Quantum ◽

Type Ii ◽

Thermally Activated ◽

Strained Sige

Photoluminescence (PL) of strained SiGe/Si multiple quantum wells (MQW) with flat and undulated SiGe well layers was studied at different temperature. With elevated temperature from 10K, the no-phonon (NP) peak of the SiGe layers in the flat samples has firstly a blue shift due to the dominant transition converting from bound excitons (BE) to free excitons (FE), and then has a red shift when the temperature is higher than 30K because of the narrowing of the band gap. In the undulated sample, however, monotonous blue shift was observed as the temperature was elevated from 10 K to 287 K. The thermally activated electrons, confined in Si due to type-II band alignment, leak into the SiGe crest regions, and the leakage is enhanced with the elevated temperature. It results in a blue shift of the SiGe luminescence spectra.

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