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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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TL;DR: In this article, the authors have grown pseudomorphic InxGa1−xAs/In0.52Al0.48As modulation-doped heterostructures by molecular beam epitaxy under carefully controlled growth conditions.
Abstract: We have grown pseudomorphic InxGa1−xAs/In0.52Al0.48As modulation‐doped heterostructures by molecular‐beam epitaxy under carefully controlled growth conditions. Mobilities as high as 13 900, 74 000, and 134 000 cm2/V s are measured at 300, 77, and 4.2 K in a heterostructure with x=0.65. Shubnikov–de Haas measurements indicate that the change in the effective mass with increasing In is not significant and is not responsible for the enhancement in mobilities. We believe that the improvement results from reduced alloy scattering, reduced intersubband scattering, and reduced impurity scattering, all of which result from a higher conduction‐band offset and increased carrier confinement in the two‐dimensional electron gas. The high‐field electron velocities have been measured in these samples using pulsed current‐voltage and pulsed Hall measurements. A monotonic increase in velocities is observed both at 300 and 77 K with an increase of In content in the channel. Velocities of 1.55×107 and 1.87×107 cm/s are meas...

64 citations

Journal ArticleDOI
TL;DR: This work derive and numerically demonstrate that perfect absorption of elastic waves can be achieved in two types of ultra-thin elastic meta-films: one requires a large value of almost pure imaginary effective mass density and a free space boundary, while the other requires a small value ofalmost pure imaginaryeffective modulus and a hard wall boundary.
Abstract: We derive and numerically demonstrate that perfect absorption of elastic waves can be achieved in two types of ultra-thin elastic meta-films: one requires a large value of almost pure imaginary effective mass density and a free space boundary, while the other requires a small value of almost pure imaginary effective modulus and a hard wall boundary. When the pure imaginary density or modulus exhibits certain frequency dispersions, the perfect absorption effect becomes broadband, even in the low frequency regime. Through a model analysis, we find that such almost pure imaginary effective mass density with required dispersion for perfect absorption can be achieved by elastic metamaterials with large damping. Our work provides a feasible approach to realize broadband perfect absorption of elastic waves in ultra-thin films.

64 citations

Journal ArticleDOI
TL;DR: In this paper, a stochastic range of p-Mg2Si1−xSnx was synthesized to optimize the thermoelectric properties of n-type Mg2(Si,Sn) with respect to composition, and the experimental data were analyzed in the framework of a single parabolic band model.
Abstract: We have synthesized the complete stoichiometric range of p-Mg2Si1−xSnx, striving to optimize the thermoelectric properties of p-type Mg2(Si,Sn) with respect to composition. The experimental data are analyzed in the framework of a single parabolic band (SPB) model and we can show that the thermoelectric properties can be well presented if acoustic phonon scattering and alloy scattering are taken into account. We find that the maximum achievable carrier concentration and power factor increase with higher Sn content. Also, the carrier mobility increases strongly from Mg2Si to Mg2Sn due to the changing density of states effective mass for the valence band which decreases from to . Retrieval of the acoustic phonon scattering potential (EDef = 9 eV) and the alloy scattering parameter (EAS = 0.5 eV) allows for modelling the thermoelectric properties for any arbitrary composition. Hence, we can predict the optimum zT for x ≈ 0.65–0.7 and the maximum power factor for Sn-rich compositions. Furthermore, we reveal that a significant improvement of the thermoelectric properties of Si-rich compositions can be achieved by increasing the carrier concentration experimentally and that the disparity between n- and p-type Mg2(Si,Sn) is due to the differences between the valence and the conduction bands and not the interaction potentials.

64 citations

Journal ArticleDOI
TL;DR: It is found that the generation of amphoteric native defects strongly limits maximum achievable carrier concentrations for nanowires with small widths where quantum confinement is appreciable.
Abstract: We have calculated the effects of quantum confinement on maximum achievable free carrier concentrations in semiconductor nanowires. Our calculations are based on the amphoteric defect model, which describes the thermodynamic doping limit in semiconductors in terms of the compensation of external dopants by native defects. We find that the generation of amphoteric native defects strongly limits maximum achievable carrier concentrations for nanowires with small widths where quantum confinement is appreciable. The magnitude of this effect in a given material is found to be determined by two material properties: the effective mass of the free carriers, and the position of the conduction (n-type) or valence band (p-type) edge on the absolute energy scale. These results offer a simple, predictive guideline for designing nanostructure devices and contacts where high doping levels are needed.

64 citations

Journal ArticleDOI
TL;DR: In this article, two very accurate methods are developed, one based on the shooting method and the other on the relaxation method, for calculating the eigenenergies and eigenfunctions of states in a quantum well with an applied electric field.
Abstract: Two very accurate methods are developed, one based on the shooting method and the other on the relaxation method, for calculating the eigenenergies and eigenfunctions of states in a quantum well with an applied electric field. These methods, which give accuracies greater than 0.001 meV, are well controlled, give the quantum‐well eigenfunctions, and are easily applied to situations of varying potential and effective mass. Comparisons with the variational approach of Bastard and others are made. These techniques allow one to follow the development of the quantum‐well eigenstate outside the well and to determine the validity of the quasi‐bound state approximation. Recent results in the literature showing that the ground‐state hole eigenfunction becomes unbound at moderate electric fields are shown to be erroneous. Detailed calculations are presented for the electron (ground and first excited) and hole (ground) eigenstates of a quantum well with width 85 A, and barrier heights of 240 (conduction band) and 160...

64 citations


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