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.

Defect Modes and Homogenization of Periodic Schrödinger Operators

Abstract: We consider the discrete eigenvalues of the operator He = − Δ+ V (x )+ e2Q(ex), where V (x) is periodic and Q(y) is localized on R d , d ≥ 1. For e> 0 and sufficiently small, discrete eigenvalues may bifurcate (emerge) from spectral band edges of the periodic Schrodinger operator, H0 = −Δx + V (x), into spectral gaps. The nature of the bifurcation depends on the homogenized Schrodinger operator LA,Q = −∇y · A∇y + Q(y). Here, A denotes the inverse effective mass matrix, associated with the spectral band edge, which is the site of the bifurcation.

First-principles study on the effective masses of zinc-blend-derived Cu2Zn−IV−VI4 (IV = Sn, Ge, Si and VI = S, Se)

Abstract: The electron and hole effective masses of kesterite (KS) and stannite (ST) structured Cu2Zn−IV−VI4 (IV = Sn, Ge, Si and VI = S, Se) semiconductors are systematically studied using first-principles calculations. We find that the electron effective masses are almost isotropic, while strong anisotropies are observed for the hole effective masses. The electron effective masses are typically much smaller than the hole effective masses for all studied compounds. The ordering of the topmost three valence bands and the corresponding hole effective masses of the KS and ST structures are different due to the different sign of the crystal-field splitting. The electron and hole effective masses of Se-based compounds are significantly smaller compared to the corresponding S-based compounds. They also decrease as the atomic number of the group IV elements (Si, Ge, Sn) increases, but the decrease is less notable than that caused by the substitution of S by Se.

Effect of effective mass and spontaneous polarization on photocatalytic activity of wurtzite and zinc-blende ZnS

Abstract: Semiconductor zinc sulphide (ZnS) has two common phases: hexagonal wurtzite and cubic zinc-blende structures. The crystal structures, energy band structures, density of states (DOS), bond populations, and optical properties of wurtzite and zinc-blende ZnS were investigated by the density functional theory of first-principles. The similar band gaps and DOS of wurtzite and zinc-blende ZnS were found and implied the similarities in crystal structures. However, the distortion of ZnS4 tetrahedron in wurtzite ZnS resulted in the production of spontaneous polarization and internal electric field, which was beneficial for the transfer and separation of photogenerated electrons and holes.

Shallow Acceptor States in ZnTe and CdTe

Abstract: The group $\mathrm{V}A$ element P and the group $\mathrm{I}A$ elements Li and Na give rise to shallow acceptor centers in ZnTe and in CdTe. An analysis of the carrier concentration data for Li-doped ZnTe and P-doped ZnTe on the basis of a single-level acceptor and nondegenerate statistics indicates that P and Li produce shallow, hydrogenic-type acceptor levels in ZnTe. Annealing studies demonstrate that the shallow levels in Li-doped ZnTe and CdTe may be removed by heat treatment at 250\ifmmode^\circ\else\textdegree\fi{}C for tens of hours. The concentrations of shallow acceptors in P-doped ZnTe and Na-doped ZnTe are relatively unchanged by the annealing procedure. The effective mass for holes in ZnTe as deduced from the Hall analysis is $0.36m$, where $m$ is the free-electron mass.

Kinematics and dynamics of atomic-beam scattering on liquid and self-assembled monolayer surfaces.

Abstract: We have conducted investigations of the energy transfer dynamics of atomic oxygen and argon scattering from hydrocarbon and fluorocarbon surfaces. In light of these results, we appraise the applicability and value of a kinematic scattering model, which views a gas-surface interaction as a gas-phase-like collision between an incident atom or molecule and a localized region of the surface with an effective mass. We have applied this model to interpret the effective surface mass and energy transfer when atoms strike two different surfaces under identical bombardment conditions. To this end, we have collected new data, and we have re-examined existing data sets from both molecular-beam experiments and molecular dynamics simulations. We seek to identify trends that could lead to a robust general understanding of energy transfer processes induced by collisions of gas-phase species with liquid and semi-solid surfaces.