Influence of Electromechanical Effects and Wetting Layers on Band Structures of AIN/GaN Quantum Dots and Spin Control

In a series of recent papers we demonstrated that coupled electromechanical effects can lead to pronounced contributions in band structure calculations of low dimensional semiconductor nanostructures LDSNs such as quantum dots QDs , wires, and even wells. Some such effects are essentially nonlinear. Both strain and piezoelectric effects have been used as tuning parameters for the optical response of LDSNs in photonics, band gap engineering, and other applications. However, the influence of spin orbit effects in presence of external magnetic field on single and vertically coupled QD has been largely neglected in the literature. The electron spin splitting terms which are coupled to the magnetic field through the Pauli spin matrix in these QDs become important in the design of optoelectronic devices as well as in tailoring properties of QDs in other applications areas. At the same time, single and vertically stacked QDs are coupled with electromagnetic and mechanical fields which become increasingly important in many applications of LDSN-based systems, in particular, where spin splitting energy is important. These externally applied electric and magnetic fields as well as the separation between the vertically coupled QDs can be used as tuning parameters. Indeed, as electromagnetic and elastic effects are often significant in LDSNs, it is reasonable to expect that the externally applied magnetic fields oriented along a direction perpendicular to the plane of two-dimensional electron gas in the QDs may also be used as a tuning parameter in the application of light emitting diodes, logic devices, for example, OR gates, AND gates and others. In this paper, by using the fully coupled model of electroelasticity, we analyze the influence of these effects on optoelectronic properties of QDs. Results are reported for III–V type semiconductors with a major focus given to AlN/GaN based QD systems

Coupled problems in analysis of quantum dots with multiband models

We investigate the influence of piezoelectromechanical effects on the band structures of electron (hole) states in wurtzite quantum dots. We apply the 8-band k · p method and solve the corresponding eigenvalue (partial differential equations) problem for quantum dots with wetting layers based on the Finite Element Method. The coupled multiphysics model includes the piezoelectromechanical part and the band structure calculation part for electrons (holes) in quantum dots. We show that the piezoelectromechanical effects bring the localization of electron states at the top of the dots and hole states at the bottom of the dots

Gate control of a quantum dot single-electron spin in realistic confining potentials: anisotropy effects

Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and its spin can be manipulated through the application of gate potentials. In this paper, we present numerical simulations of such spins in single electron devices for realistic (asymmetric) confining potentials in two-dimensional electrostatically confined quantum dots. Using analytical and numerical techniques we show that breaking the in-plane rotational symmetry of the confining potential leads to a significant effect on the tunability of the g-factor with applied gate potentials. In particular, anisotropy extends the range of tunability to larger quantum dots.Comment: 7 pages, 13 figure