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.

Suppression of auger processes in confined structures.

Abstract: We explore how the size and shape of the microscopic confinement potential affects the nonradiative Auger decay rate of confined carriers. Calculations conducted in the two-band, effective mass Kane model unambiguously show that smoothing out the confinement potential could reduce the rate by more than 3 orders of magnitude relative to the rate in structures with abruptly terminating boundaries. As the confinement potential width is increased, the calculated rate decreases overall, exhibiting very deep minima at regular widths. Such minima suggest that nanocrystals of “magic sizes” can exist for which nonradiative Auger processes are strongly suppressed.

Valence band effective-mass expressions in the sp 3 d 5 s * empirical tight-binding model applied to a Si and Ge parametrization

Abstract: Exact, analytic expressions for the valence band effective masses in the spin-orbit, ${\mathrm{sp}}^{3}{d}^{5}{s}^{*}$ empirical tight-binding model are derived. These expressions together with an automated fitting algorithm are used to produce improved parameter sets for Si and Ge at room temperature. Detailed examinations of the analytic effective-mass expressions reveal critical capabilities and limitations of this model in reproducing simultaneously certain gaps and effective masses. The [110] masses are shown to be completely determined by the [100] and [111] masses despite the introduction of $d$ orbitals into the basis.

Heterojunction band offsets and effective masses in III-V quaternary alloys

Abstract: Estimates of valence-band and conduction-band offsets for lattice-matched and pseudomorphic strained heterostructures of six technologically important III-V quaternary alloys are presented. Valence-band offsets are obtained via interpolation of the theory-based results of Van de Walle's 'model-solid' approach for the binary constituents. Estimates for band gap differences are obtained via interpolation of the experimental band gap energies of the ternary constituents. Adding the valence-band offset and band gap difference gives an estimate of the conduction-band offset. Band-edge effective masses at Gamma are determined from a linear interpolation of the effective masses of the binary constituents, obtained from self-consistent ab initio band structure calculations. Results are shown to agree well with the outcome of experiments.

Spectroscopy of the solid-state analogues of the hydrogen atom: donors and acceptors in semiconductors

Abstract: Under suitable circumstances imperfections in semiconductors can bind electrons (holes) with a binding energy small compared to the intrinsic energy gap of the host; the wavefunctions characterising the energy levels of the imperfection are extended over many lattice spacings. This review discusses the electronic energy levels of chemical impurities in the classic group IV elemental and the III-V and II-VI compound semiconductors. The large dielectric constant of the host, the anisotropic effective mass tensor and/or the small effective mass of the charge carrier are the factors which play a significant role in the description of the electronic energy levels; they can be viewed as scaled-down versions of the hydrogen atom with bound states having binding energies orders of magnitude smaller than those of the hydrogen atom. The authors present the experimental results on the spectroscopy of donors and acceptors in semiconductors together with the theory necessary for their interpretation. They discuss the experimental results and the theory of the bound states of impurities in the context of the symmetry and the effective-mass parameters of the band extrema with which they are associated. Effects of external perturbation-piezo- and magneto-spectroscopy-are presented both from experimental and theoretical points of view. The review concludes with the experimental observations on the linewidths of the excitation spectra of donors and acceptors in semiconductors and an analysis of the causes underlying them.