Anisotropic to Isotropic Transition in Monolayer Group-IV Tellurides

Monolayer group-IV tellurides with phosphorene-derived structures are attracting increasing research interest because of their unique properties. Here, we systematically studied the quasiparticle electronic and optical properties of two-dimensional group-IV tellurides (SiTe, GeTe, SnTe, PbTe) using the GW and Bethe–Salpeter equation method. The calculations revealed that all group-IV tellurides are indirect bandgap semiconductors except for monolayer PbTe with a direct gap of 1.742 eV, while all of them are predicted to have prominent carrier transport ability. We further found that the excitonic effect has a significant impact on the optical properties for monolayer group-IV tellurides, and the predicted exciton binding energy is up to 0.598 eV for SiTe. Interestingly, the physical properties of monolayer group-IV tellurides were subject to an increasingly isotropic trend: from SiTe to PbTe, the differences of the calculated quasiparticle band gap, optical gap, and further exciton binding energy along different directions tended to decrease. We demonstrated that these anisotropic electronic and optical properties originate from the structural anisotropy, which in turn is the result of Coulomb repulsion between non-bonding electron pairs. Our theoretical results provide a deeper understanding of the anisotropic properties of group-IV telluride monolayers.

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Electronic and optical properties of low-dimensional group-IV monochalcogenides

Journal of Applied Physics ◽

10.1063/5.0016003 ◽

2020 ◽

Vol 128 (12) ◽

pp. 121101

Author(s):

Lídia C. Gomes ◽

A. Carvalho

Keyword(s):

Optical Properties ◽

Group Iv ◽

Electronic And Optical Properties ◽

Dimensional Group ◽

Low Dimensional

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Electronic and optical properties of the group IV doped copper gallium chalcopyrites

Thin Solid Films ◽

10.1016/j.tsf.2010.09.039 ◽

2010 ◽

Vol 519 (4) ◽

pp. 1435-1440 ◽

Cited By ~ 16

Author(s):

C. Tablero

Keyword(s):

Optical Properties ◽

Group Iv ◽

Electronic And Optical Properties

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Capturing excitonic and polaronic effects in lead iodide perovskites from many-body perturbation theory

Journal of Materials Chemistry C ◽

10.1039/d1tc03843e ◽

2021 ◽

Author(s):

Pooja Basera ◽

Arunima Singh ◽

Deepika Gill ◽

Saswata Bhattacharya

Keyword(s):

Optical Properties ◽

Perturbation Theory ◽

Binding Energy ◽

Electronic Properties ◽

Effective Mass ◽

Exciton Binding Energy ◽

Many Body ◽

Energy Materials ◽

Lead Iodide ◽

Many Body Perturbation Theory

Lead iodide perovskites have attracted considerable interest as promising energy-materials. However, till date, several key electronic properties such as optical properties, effective mass, exciton binding energy and the radiative exciton...

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The effect of substitutional doping of Yb2+ on structural, electronic, and optical properties of CsCaX3 (X: Cl, Br, I) phosphors: A first-principles study

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/ac3583 ◽

2021 ◽

Author(s):

Rashid Khan ◽

Kaleem Ur Rahman ◽

Qingmin Zhang ◽

Altaf Ur Rahman ◽

Sikander Azam ◽

...

Keyword(s):

Optical Properties ◽

First Principles ◽

Dielectric Susceptibility ◽

Hybrid Functional ◽

Generalized Gradient ◽

Electronic Band ◽

Electronic And Optical Properties ◽

Substitutional Doping ◽

Bandgap Semiconductors ◽

Magnetic Insulator

Abstract Using first-principles calculations, the effects of Yb$^{2+}$ substitutional doping on structural, electronic, and optical properties of a series of perovskite compounds CsCaX$_3$ (X: Cl, Br, I), have been investigated. We employed generalized gradient approximation (GGA) and HSE hybrid functional to study the electronic and optical properties. A series of pristine CsCaX$_3$(X: Cl, Br, I) is characterized as a non-magnetic insulator with indirect bandgap perovskite materials. These phosphor materials are suitable candidates for doping with lanthanide series elements to tune their electronic bandgaps according to our requirements because of their wide bandgaps. The calculated electronic bandgaps of CsCaX$_3$ (X: Cl, Br, I) are 3.7 eV(GGA) and 4.5 eV (HSE) for CsCaI$_3$, 4.5 eV (GGA) and 5.3 eV (HSE) for CsCaBr$_3$, and 5.4 eV (GGA) and 6.4 eV (HSE) for CsCaCl$_3$. According to formation energies, the Yb$^{2+}$ doped at the Ca-site is thermodynamically more stable as compared to all possible atomic sites. The electronic band structures show that the Yb$^{2+}$ doping induces defective states within the bandgaps of pristine CsCaX$_3$. As a result, the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) become the direct bandgap semiconductors. The defective states above the VBM are produced due to the $f$-orbital of the Yb atom. The impurity states near the CBM are induced due to the major contribution of $d$-orbital of the Yb atom and the minor contribution of $s$-orbital of the Cs atom. The real and imaginary parts of the dielectric function, optical reflectivity, electron energy loss spectrum, extinction coefficient, and refractive index of pristine and Yb$^{2+}$ doped CsCaX$_3$ were studied. The optical dispersion results of dielectric susceptibility closely match their relevant electronic structure and align with previously reported theoretical and experimental data. We conclude that the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) are appealing candidates for optoelectronic devices.

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The Structural, Electronic, and Optical Properties of Ge/Si Quantum Wells: Lasing at a Wavelength of 1550 nm

Nanomaterials ◽

10.3390/nano10051006 ◽

2020 ◽

Vol 10 (5) ◽

pp. 1006

Author(s):

Hongqiang Li ◽

Jianing Wang ◽

Jinjun Bai ◽

Shanshan Zhang ◽

Sai Zhang ◽

...

Keyword(s):

Optical Properties ◽

Quantum Wells ◽

Room Temperature ◽

Light Emission ◽

Single Mode ◽

Group Iv ◽

Light Power ◽

Fully Integrated ◽

Electronic And Optical Properties ◽

Novel Approach

The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.

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