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Effective mass (solid-state physics)

About: Effective mass (solid-state physics) is a research topic. Over the lifetime, 12539 publications have been published within this topic receiving 295485 citations.


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Journal ArticleDOI
R. Khordad1
TL;DR: In this article, the position-dependent effective mass in a GaAs/AlxGa1−xAs cubic quantum dot is studied and an analytic relation for studying the position dependent effective mass is obtained for the intersubband optical absorption coefficient and refractive index change in the quantum dot.
Abstract: In this paper, we first obtain an analytic relation for studying the position-dependent effective mass in a GaAs/AlxGa1−xAs cubic quantum dot. Then, the effect of position-dependent effective mass on the intersubband optical absorption coefficient and the refractive index change in the quantum dot are studied. Our numerical calculations are performed using both a constant effective mass and the position-dependent effective mass. We calculate the linear, nonlinear and total intersubband absorption coefficient and refractive index change as a function of the incident optical intensity and structural parameters such as dot length. The results obtained from the present work show that spatially varying electron effective mass plays an important role in the intersubband optical absorption coefficient and refractive index change in a cubic quantum dot.

67 citations

Journal ArticleDOI
Zhujie Li1, Ying Dai1, Xiangchao Ma1, Yingtao Zhu1, Baibiao Huang1 
TL;DR: Electronic structures, and effective masses of electron and hole at energy band edges are theoretically investigated by employing spin-polarized density functional theory calculations and demonstrate that the separation and transfer of photogenerated carriers along the [011] direction may be more effective than other possible directions.
Abstract: Recently, Cu2(OH)PO4 was found as the first photocatalyst active in the near-infrared(NIR) region of the solar spectrum (Angew. Chem., Int. Ed., 2013, 52, 4810; Chem. Eng. News, 2013, 91, 36), motivating us to explore systemically its photocatalytic mechanism under near-infrared light and how to improve and tune its photocatalytic performance. Herein, electronic structures, and effective masses of electron and hole at energy band edges are theoretically investigated by employing spin-polarized density functional theory calculations. The calculated energy band structure supports the absorption spectra of Cu2(OH)PO4 in the NIR region corresponding to the electron excitation from the valence band to the unoccupied bands in the gap. Our charge density analysis indicates that the O atoms in the hydroxyl serves as the effective bridge for the favoring separation of the photogenerated electron–hole pairs. Furthermore, the effective masses of electron and hole analysis demonstrate that the separation and transfer of photogenerated carriers along the [011] direction may be more effective than other possible directions. A qualitative comparison of carrier transfer ability along all the directions in the specific planes is displayed by the three-dimensional band structure. Interestingly, the calculated net dipole moment for the two basic units of Cu2(OH)PO4, octahedron and trigonal bipyramid, indicate that the macroscopic dipole moment for Cu2(OH)PO4 is zero, however, the distorted octahedron unit has a net dipole moment, which enables us to tune the macroscopic dipole moment by doping. The present work provides theoretical insight leading to a better understanding of the photocatalytic performance of Cu2(OH)PO4 and it may be beneficial to prepare more efficient Cu2(OH)PO4 for NIR light photocatalysis, which will also be helpful to design and prepare novel photocatalysts.

67 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the band structure and transport properties of GeSe and its heterostructures, and found that GeSe exhibits a markedly anisotropic electronic transport, with maximum conductance along the armchair direction.
Abstract: Group-IV monochalcogenides are emerging as a new class of layered materials beyond graphene, transition metal dichalcogenides (TMDCs), and black phosphorus (BP). In this paper, we report experimental and theoretical investigations of the band structure and transport properties of GeSe and its heterostructures. We find that GeSe exhibits a markedly anisotropic electronic transport, with maximum conductance along the armchair direction. Density functional theory calculations reveal that the effective mass is 2.7 times larger along the zigzag direction than the armchair direction; this mass anisotropy explains the observed anisotropic conductance. The crystallographic orientation of GeSe is confirmed by angleresolved polarized Raman measurements, which are further supported by calculated Raman tensors for the orthorhombic structure. Novel GeSe/MoS2 p-n heterojunctions are fabricated, combining the natural p-type doping in GeSe and n-type doping in MoS2. The temperature dependence of the measured junction current reveals that GeSe and MoS2 have a type-II band alignment with a conduction band offset of ∼0.234 eV. The anisotropic conductance of GeSe may enable the development of new electronic and optoelectronic devices, such as high-efficiency thermoelectric devices and plasmonic devices with resonance frequency continuously tunable through light polarization direction. The unique GeSe/MoS2 p-n junctions with type-II alignment may become essential building blocks of vertical tunneling field-effect transistors for low-power applications. The novel p-type layered material GeSe can also be combined with n-type TMDCs to form heterogeneous complementary metal oxide semiconductor (CMOS) circuits.

67 citations

Journal ArticleDOI
TL;DR: In this article, the design and the characterization of artificial structures made of periodical distributions of structured cylindrical scatterers embedded in a 2D waveguide is described. But the analysis is focused on the frequencies where they behave like materials with negative density or density near zero (DNZ).
Abstract: We report the design and the characterization of artificial structures made of periodical distributions of structured cylindrical scatterers embedded in a two-dimensional (2D) waveguide. For certain values of their geometrical parameters they show simultaneously negative effective bulk modulus and negative effective mass density. Here our analysis is focused on the frequencies where they behave like materials with negative density or density near zero (DNZ). The scattering units consist of a rigid cylindrical core surrounded by an anisotropic shell divided in angular sectors. The units are embedded in a 2D waveguide whose height is smaller than the length of the cylinders, which makes the structure quasi-2D. We have obtained the dispersion relation of the surface acoustic waves excited at frequencies with negative effective density. Also, we report phenomena associated with their DNZ behavior, such as tunneling through narrow channels, control of the radiation field, perfect transmission through sharp corners, and power splitting. Preliminary experiments performed on samples with millimeter-scale dimensions demonstrated their single-negative behavior, with the main drawback being the strong losses measured at the frequencies where the negative behavior is observed.

67 citations

Journal ArticleDOI
TL;DR: In this paper, high quality In2O3 single crystals of bcc structure were grown by chemical vapour transport and the transport properties showed characteristics best describable by the degenerate semiconductor model.
Abstract: High quality In2O3 single crystals of bcc structure were grown by chemical vapour transport. The temperature dependence of resistivity, Hall constant, and mobility yielded an electron density of n = 1.3 × 1019 cm−3. The transport properties showed characteristics best describable by the degenerate semiconductor model. The crystals were additionally investigated by high resolution angular resolved photoelectron spectroscopy (ARPES). Emission from the valence band and the partially filled conduction band at the Γ point yielded a direct bandgap of (2.7 ± 0.1)eV. The partially filled conduction band furthermore enabled the determination of its three dimensional Fermi surface and the effective masses m* by ARPES.

67 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202215
2021410
2020421
2019395
2018362
2017412