Tuning the structural and optical properties of 1.3-μm InAs/GaAs quantum dots by a combined InAlAs and GaAs strained buffer layer

A combined InAlAs and GaAs strained buffer layer was presented to tailor the structural and optical properties of 1.3-μm InAs/GaAs quantum dots. This growth technique exhibits an increment of InAs quantum-dot density from ${\text{1.6×10}}^{10}$ to ${\text{2.8×10}}^{10}\hspace{0.17em}{\mathrm{cm}}^{\text{−2}}$ and an improvement of energy separation between the quantum-dot ground and first-excited states from 84 to 93 meV upon adjusting the thickness of GaAs in InAlAs–GaAs buffer layer. We also investigate the effect of an InAlAs layer surrounding InAs quantum dots on photoluminescence intensity with increasing the thickness of InAlAs layer in a 6-nm InAlAs–InGaAs composite cap layer, and no negative effect has been observed.