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.

Bandgap engineering of graphene: A density functional theory study

Abstract: Three ways of engineering the bandgap of graphene, i.e., surface bonding, isoelectronic codoping, and alternating electrical/chemical environment, are analyzed with the effective mass approximation and density-functional theory calculations. Surface bonding on graphene would lift its top σ valence bands above π valence states, open a sp3 gap, but also bury the linearly dispersive bands into the valence σ bands. Isoelectronic codoping and asymmetric electrical or chemical environment may open the π−π∗ gap of graphene by breaking its sublattice equivalence. The calculated effective mass versus bandgap may provide useful guidance for the future experimental efforts to fabricate graphene-based semiconductors.

Electronic Structure and Electrical Conductivity of Undoped LiFePO4

Abstract: The electronic structure of LiFePO 4 underpins transport properties important to its use as a lithium storage electrode. Here we have calculated the electronic structure of LiFePO 4 in the ordered olivine structure by a first-principles method to determine (i) the effective mass of carriers and (ii) the nature of the band structure. The electrical conductivity in high purity undoped LiFePO 4 has also been measured experimentally. Spin-polarized calculations show a large electron effective mass and a much smaller but highly anisotropic hole effective mass, suggesting that hole-doped compositions should have the greater electronic conductivity. More surprisingly, the calculations show that this polyanion compound is a half-metal with spin-sensitive band structure, like some other oxides being studied for spintronics applications. This previously unappreciated aspect of the LiFePO 4 electronic structure may play a role in determining transport properties including those relevant to electrochemical applications.

The electron effective mass in heavily doped GaAs

Abstract: A resolution to the order k6 of the three-level equation of Kane allows the authors to obtain a new expression for the conduction band energy and so new analytical expressions for the electron effective masses in the range of carrier concentration 1016-1019 cm-3. The calculated values of the conduction effective mass as a function of carrier density agree well, for the first time, with experimental values, which were obtained from Shubnikov-de Haas experiments by using a new expression for the oscillation amplitude. In this expression the authors take into account the effect of medium-range potential fluctuations induced by crystal inhomogeneities.

Structural, electronic, and effective-mass properties of silicon and zinc-blende group-III nitride semiconductor compounds

Abstract: The electronic band structures of silicon and the zinc-blende-type III-N semiconductor compounds BN, AlN, GaN, and InN are calculated by using the self-consistent full potential linear augmented plane wave method within the local-density functional approximation. Lattice constant, bulk modulus, and cohesive energy are obtained from full relativistic total-energy calculations for Si and for the nitrides. Band structures and total density of states (DOS) are presented. The role played by relativistic effects on the bulk band structures and DOS is discussed. In order to provide important band structure-derived properties, such as effective masses and Luttinger parameters, the ab initio band structure results are linked with effective-mass theory. Electron, heavy-, light-, and split-off-hole effective masses, as well as spin-orbit splitting energies are extracted from the band-structure calculations. By using the Luttinger-Kohn $6\ifmmode\times\else\texttimes\fi{}6$ effective-mass Hamiltonian we derive the corresponding Luttinger parameters for the materials. A comparison with other available theoretical results and experimental data is made.