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The smaller lattice constant and high band gap quaternary – capped AlxInyGa1−x−yAs material acts as a confinement – enhancing (CE) barrier layer in type – I InAs/InxGa1−xAs sub-monolayer (SML) quantum dot (QD) optoelectronic devices. The QDs grown inside In0.15Ga0.85As matrix surrounded by AlxGayIn1−x−yAs/GaAs barriers, resembles of dot –in – a – well (DWELL) heterostructure to achieve higher device performance. A larger in – plane compressive strain gets induced due to smaller lattice constant of CE barrier layer and this effect can be probed for designing higher modal gain and low – threshold current density vertical cavity surface – emitting lasers (VCSELs). The decreasing In content in CE layers increases the compressive strain in QDs, leading to reduced threshold current by decreasing (increasing) the background carrier concentration (conduction band, CB offset). The increased CB offset with Al (0.21), In (0.21) contents will therefore prevent the carriers from escaping to quantum well (QW) or barrier layers, thus non – radiative leakage current effects can be reduced. We have analyzed the primary strain tensors: hydrostatic and biaxial strain, photoluminescence (PL) emission energies using Nextnano++ simulations based on 8 – band k.p theory. Both the hydrostatic and biaxial strain increases inside QD, capping layers for increasing In (Al) composition, facilitating the threshold current reduction. Through the strain analysis, the material gain to carrier characteristics can be figured out for the efficient design of VCSELs. The QD low (19 K) and room –temperature (300 K) PL eigen energies were found at 1.1805 (1.1759) eV and 1.111 (1.177) eV for Al0.2Ga0.8As/GaAs and Al0.21Ga0.58In0.21As/GaAs CE layers.
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