Self-assembled quantum dots: A study of strain energy and intersubband transitions

Abstract

Articles you may be interested inEffects of internal strain and external pressure on electronic structures and optical transitions of self-assembled InxGa1−xAs/GaAs quantum dots: An experimental and theoretical study Combined optical and electrical studies of the effects of annealing on the intrinsic states and deep levels in a self-assembled InAs quantum-dot structure Suppression of temperature sensitivity of interband emission energy in 1.3-μm-region by an InGaAs overgrowth on self-assembled InGaAs/GaAs quantum dots In this article we examine the strain energy and intersubband optical transitions in self-assembled dots on GaAs and InP substrates. On the GaAs substrate, in addition to the InAs/GaAs dots we examine strain compensated InAs/GaAsP dots on GaAs substrates. We find that the strain energy configuration profile shows that there is preference for certain dot sizes and shapes. Our calculated dot sizes agree well with experimental observations. We find that the addition of phosphorus in the covering matrix reduces the total strain energy of the system with little effects on the intersubband transition strength for the vertical incident light. The reduced strain energy should allow one to incorporate a large number of dot array stacks for devices such as lasers and detectors and thus increases the optical responses. Our studies for the InAs/InP system show that due to the lower strain mismatch there is no particular preference for dot sizes. The optical response for intersubband transitions is weaker and occurs at longer wavelengths in comparison to the InAs/GaAs dots.

OMVPE Grown InAs Quantum Dots for Application in Nanostructured Photovoltaics

“…For InAs QDs in the size range previously measured by AFM, we expect luminescence from the QDs between 0.9-1.1 eV (~1200-1300 nm) [6]. For the two samples grown with a thin 1 nm GaAs cap, very weak 1 eV QD luminescence was observed, although strong peaks were observed in the 1.2-1.35 eV range.…”

Structural properties of self-organized semiconductor nanostructures

“…The impact of quantum dots on detectors and lasers has been reviewed by Bimberg et al ͑1999͒ and more recently by Grundmann ͑2002͒, Ledentsov et al ͑2002͒, Ustinov and Zhukov ͑2002͒, Shchukin et al ͑2003͒, and Ustinov et al ͑2003͒. Quantum dot detectors with genuine zerodimensional properties have been fabricated mainly from buried InAs dot layers in GaAs. In comparison to InAs-based quantum well infrared detectors ͑QWIP's͒ the quantum dot infrared detectors ͑QDIP's͒ in principle should not suffer from restrictions of the intersubband transition selection rules ͑E z 0͒, i.e., they are sensitive to light with any incidence angle, because of carrier confinement in all three dimensions ͑Chen et al., 2001;Liu, Gao, et al, 2001;Lin and Singh, 2002;Ye et al, 2002;Aslan et al, 2003͒. However, the quantum dot shape has a significant influence on the polarization selection rules due to the low aspect ratio.…”

The electronic properties of a core/shell/well/shell spherical quantum dot with and without a hydrogenic impurity

“…1 Because of these properties, the nanostructures have a wide area of the research and interest for the scientists. 2 The electron motion can be confined in all three dimensions with advanced manufacturing technology and so, these improvements have made possible the production of quantum dots (QDs). These confinements have led to sharp energy levels and density of states as which were found in atoms.…”