Effects of In, Sb and N Alloyed Capping on the Electronic Band Structures of Vertically Coupled InAs SK-SML Quantum Dot System

The effects of strain, quantum confinement, and composition on the optical and electronic properties of vertically-coupled InAs/GaAs quantum dots (QDs) capped with a thin layer composing In, Sb, and N ternary/quaternary alloys are investigated theoretically. In this paper, we have used five different cappings such as GaAs
$_{1-x}$
Sb
$_{x}$
, Ga
$_{1-z}$
In
$_{z}$
As
$_{1-x}$
Sb
$_{x}$
, GaAs
$_{1-y}$
N
$_{y}$
, and GaAs
$_{1-x-y}$
Sb
$_{x}$
N
$_{y}$
along with conventional GaAs capping to analyze its effects on the emission wavelength, strain build-up, band alignment, electron and hole probability density function, and the eigen energy states in a ten-layer vertically-ordered InAs Stranksi-Krastanov (SK) QDs coupled electronically to six-stacks of Submonolayer (SML) QDs. Strain, being a vital component in a coupled self-assembled QD system, governs the presence of eigen states in the QDs, thus, altering their optical properties.Influenced by strain in coupled QDs, interestingly, it has been observed that quantum confinement in a coupled structure governed the presence of eigen energies, especially in dilute-N based capping materials. The emission wavelength extended from 1.16 (1.22)
$\mu$
m in conventional GaAs capping to 1.21 (1.28)
$\mu$
m in GaAsSb capping structure at a temperature of 15 (300) K. By inclusion of just 2.5
$\%$
of N in the GaAsSb layer induced a redshift of
$\sim$
200 (230) nm compared to conventional GaAs capping extending the emission wavelength to 1.36 (1.45)
$\mu$
m at a temperature of 15 (300) K falling in the telecommunication wavelength window. Independent tailoring of electronic energy levels in both the conduction and valence bands is made possible with the simultaneous presence of Sb and N in the capping material.