Influence of electromechanical effects and wetting layers on band structures of AlN/GaN quantum dots and spin control

Prabhakar, S. and Melnik, R.

Journal of Applied Physics, 108, 064330, 2010


In a series of recent papers we demonstrated that coupled electro-mechanical effects can lead to pronounced contributions in band structure calculations of low dimensional semiconductor nanostructures (LDSNs) such as quantum dots, 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 Quantum Dots (QDs) 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 tayloring 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 quantum dots 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 $2$ Dimensional Electron Gas ($2$DEG) 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.