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.

Confinement effects in quasi-stoichiometric CeO2 nanoparticles

Abstract: This paper deals with the analysis of structural and electronic effects of size in quasi-stoichiometric CeO2 nanoparticles prepared by a microemulsion method. The preparation method yields highly controlled materials in terms of particle size distribution and chemical oxidation state, with the presence of Ce(III) species only below an average particle size of ca. 8 nm. The rather low quantity of Ce reduced ions produces marked differences with confinement effects previously reported in the literature. A steady behavior of the fluorite lattice parameter is observed as a function of size in the 5–10 nm range. In this range, the bandgap displays a small decrease of ca. 0.1 eV, with significant differences from the behavior expected on the basis of the effective mass approximation. These structural and electronic properties are rationalized on the basis of the characterization of the materials.

Introduction to Modeling Thermoelectric Transport at High Temperatures

Abstract: This chapter provides experimentalists a basic outline for analyzing/modeling thermoelectric transport at high temperatures. The single parabolic band (SPB) model is a powerful analytical tool when investigating thermoelectric transport. The SPB model is something of a diagnostic tool for both overall thermoelectric efficiency and the existence of more complex transport behavior. Most high-performance thermoelectric materials are heavily doped semiconductors with transport properties that appear more similar to metals than semiconductors. For instance, Density functional theory (DFT) calculations predicted n-type LiZnSb to have large thermoelectric efficiency. With the DFT results for band offsets and degeneracy as a starting point, a multiparabolic band model can be pursued. The SPB model discussed hides the influence of band degeneracy within the effective mass. The effective onset temperature depends on the carrier density, where a low carrier density promotes the influence of the bipolar conduction at lower temperatures.

Optical gain in InGaN∕GaN quantum well structures with embedded AlGaN δ layer

Abstract: Optical gain characteristics of InGaN∕GaN double quantum well (QW) structures with embedded AlGaN δ layer are investigated using the multiband effective mass theory. These results are compared with those of single QW structure without a δ layer. The theoretical energies show very good agreement with the experimental results for both single and double QW structures. The inclusion effect of a δ layer is found to be dominant at a relatively low carrier density. A double QW structure has larger optical gain than the single QW structure, in particular, at higher carrier density.

Metal–insulator transitions and the effects of electron–electron interactions in two-dimensional electron systems

Abstract: Experimental results on metal–insulator transitions and the anomalous properties of strongly interacting two-dimensional electron systems are reviewed and critically analyzed. Special attention is given to recent results on strongly enhanced spin susceptibility and effective mass in low-disordered silicon MOSFETs.