Altering the Optical Properties of GaAsSb-Capped InAs Quantum Dots by Means of InAlAs Interlayers

Abstract

In this work, we investigate the optical properties of InAs quantum dots (QDs) capped with composite In0.15Al0.85As/GaAs0.85Sb0.15 strain-reducing layers (SRLs) by means of high-resolution X-ray diffraction (HRXRD) and photoluminescence (PL) spectroscopy at 77 K. Thin In0.15Al0.85As layers with thickness t = 20 Å, 40 Å, and 60 Å were inserted between the QDs and a 60-Å-thick GaAs0.85Sb0.15 layer. The type II emissions observed for GaAs0.85Sb0.15-capped InAs QDs were suppressed by the insertion of the In0.15Al0.85As interlayer. Moreover, the emission wavelength was blueshifted for t = 20 Å and redshifted for t ≥ 40 Å resulting from the increased confinement potential and increased strain, respectively. The ground state and excited state energy separation is increased reaching 106 meV for t = 60 Å compared to 64 meV for the QDs capped with only GaAsSb SRL. In addition, the use of the In0.15Al0.85As layers narrows significantly the QD spectral linewidth from 52 to 35 meV for the samples with 40- and 60-Å-thick In0.15Al0.85As interlayers.

In-Situ Tailoring of Vertically Coupled InAs p-i-p Quantum-Dot Infrared Photodetectors: Toward Homogeneous Dot Size Distribution and Minimization of In–Ga Intermixing

“…It should be mentioned that while the use of InGaAs capping layer for strain relaxation in InAs QDs is popular, it has been shown to reduce the energy gap between confined states . This problem has been circumvented variously by adopting other strategies such as GaAsSb capping layer, InGaAs and InAlAs combinational capping, etc. , Through the implementation of In 0.15 Ga 0.85 As SRL in combination with growth strategy in sample C, we have been able to extend the energy gap between confined states and hence achieve greater confinement without necessitating the employment of any other capping layer.…”

Effect of capping rate on the performance of InAs/GaAs quantum dot solar cell

“…Self-assembled quantum dots (SAQDs) grown using the Stranski-Krastanov technique have attracted a lot of attention in the past few decades due to their enormous potential for optoelectronic device applications. InAs/ GaAs QDs are one of the SAQD systems that have undergone extensive research and have been used as active materials in various optoelectronic devices with tremendous success [1][2][3]. The SAQDs QDs must be surrounded by a capping layer (CL) that shields them from the environment and prevents non-radiative recombination through surface states [4].…”

Electronic and Optical Properties of InAs QDs Grown by MBE on InGaAs Metamorphic Buffer

“…To extend the spectral range of emission, it is necessary to apply additional steps to modify the properties of the dots, mostly employing the strain engineering or modification of the QDs’ size or composition [ 11 ]. There exist at least several approaches allowing for the shifting of the emission wavelength to the telecommunication windows, for instance by using vertically-stacked QDs [ 19 , 20 , 21 , 22 , 23 ], growth up to the second critical thickness [ 24 , 25 ], controlled overgrowth of InGaAs QDs [ 26 ], adding small concentrations of nitrogen to the InAs QDs [ 27 ], applying the strain-reducing layer [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ], or the metamorphic-buffer-layer (MBL) [ 5 , 11 , 43 , 44 , 45 , 46 ]. Most of these solutions concern the use of QDs as an active region in lasers or amplifiers, while the practical demonstrations employing single GaAs-based QDs as an active element of non-classical emitters for quantum technology applications in the telecom range are still under development.…”