Hole-Pinned Defect Clusters for a Large Dielectric Constant up to GHz in Zinc and Niobium Codoped Rutile SnO.

High permittivity materials for a gigahertz (GHz) communication technology have been actively sought for some time. Unfortunately, in most materials, the dielectric constant starts to drop as frequencies increase through the megahertz (MHz) range. In this work, we report a large dielectric constant of ∼800 observed in defect-mediated rutile SnO ceramics, which is nearly frequency and temperature independent over the frequency range of 1 mHz to 35 GHz and temperature range of 50-450 K.

Comparative Chemico-Physical Analyses of Strain-Free GaAs/AlGaAs Quantum Dots Grown by Droplet Epitaxy.

We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0 . 3 Ga 0 . 7 As droplet epitaxy (DE) quantum dots (QDs).

Strain-induced control of a pillar cavity-GaAs single quantum dot photon source.

Herein, we present the calculated strain-induced control of single GaAs/AlGaAs quantum dots (QDs) integrated into semiconductor micropillar cavities. We show precise energy control of individual single GaAs QD excitons under multi-modal stress fields of tailored micropillar optomechanical resonators. Further, using a three-dimensional envelope-function model, we evaluated the quantum mechanical correction in the QD band structures depending on their geometrical shape asymmetries and, more interestingly, on the practical degree of Al interdiffusion.

Formation of ferromagnetic Co-H-Co complex and spin-polarized conduction band in Co-doped ZnO.

Magnetic oxide semiconductors with wide band gaps have promising spintronic applications, especially in the case of magneto-optic devices. Co-doped ZnO (ZnCoO) has been considered for these applications, but the origin of its ferromagnetism has been controversial for several decades and no substantial progress for a practical application has been made to date. In this paper, we present direct evidence of hydrogen-mediated ferromagnetism and spin polarization in the conduction band of ZnCoO.